Juan Guo, Lin Xiao, Liuyang Han, Hao Wu, Tao Yang, Shunqing Wu and Yafang Yin

Edited by Lloyd A. Donaldson

ABSTRACT

The relationship between the cell wall ultrastructure of waterlogged wooden archeological artifacts and the state of water bound to cell walls and free in voids is fundamental to develop consolidating and drying technologies. Herein, a lacquer-wooden ware and a boat-coffin dating 4th century BC were selected as representative artifacts to study. Wood anatomy results indicated that they belonged to Idesia sp. and Machilus sp., respectively. They exhibited a typical spongy texture, as revealed by SEM observations, and their water contents had increased significantly. Solid state NMR, Py-GC/MS, imaging FTIR microscopy and 2D-XRD results demonstrated that the deterioration resulted from the partial cleavages of both polysaccharide backbones and cellulose hydrogen-bonding networks, almost complete elimination of acetyl side chains of hemicellulose, the partial depletion of β-O-4 interlinks, as well as oxidation and demethylation/demethoxylation of lignin. These further caused the disoriented arrangement of crystalline cellulose, and the decrease in cellulose crystallite dimensions and crystallinity. In consequence, mesopores and macropores formed, and the number of moisture-adsorbed sites and their accessibility increased. Moreover, results on free water deduced by the changes of pore structure and the maximum monolayer water capacity achieved by the GAB model indicated that water in waterlogged archeological wooden artifacts was mainly free water in mesopores.

Jong Sik Kim and Geoffrey Daniel

Edited by Lloyd A. Donaldson

ABSTRACT

Although there is considerable information on the chemistry of gelatinous (G) layers in tension wood (TW) fibers consisting of S1 + S2 + G cell wall structure (poplar), little is known on the chemistry of G-layers in TW fibers organized with S1+ G structure. This study investigated the distribution of lignin and non-cellulosic polysaccharides in ash TW fibers (S1+ G) using histochemistry and immunolocalization methods. TW fibers studied were fully developed (mature fibers) and obtained from two (TW-1, TW-2) mature European ash trees (Fraxinus excelsior L.). Based on differences in microfibril angle (MFA) and TW trees used, TW fibers were mainly classified into three types; 1) Type-1 fibers with MFA almost parallel to the fiber axis that were found in TW-1, 2) Type-2 fibers with 12° MFA that were abundant at the end of growth rings of TW-1 and 3) Type-3 fibers with 10° MFA that were found in TW-2. The S3 layer was absent in all TW fibers. In this study, the secondary cell wall structure of Type-1 and Type-2/Type-3 fibers were defined as G and GL (gelatinous-like) layers, respectively. Lignin with syringyl (S) units was detected in G/GL-layers, in which intensity and patterns of lignin staining likely related to the difference in MFA between G- and GL-layers. With hemicelluloses, heteroxylan and heteromannan epitopes were detected in G/GL-layers but these were much less abundant than those in S2 layers of normal wood (NW) fibers. Like lignin, distribution patterns of heteromannan epitopes in G/GL-layers likely related to differences in MFA between fiber types. Sparse xyloglucan epitopes were also detected in G/GL-layers. Homogalacturonan epitopes were absent in G/GL-layers. All fiber types showed abundant a-1, 5-arabinan epitopes in G/GL-layers. Overall results indicate that the chemistry of ash TW fibers studied differs significantly from that of other species reported previously, specifically TW fibers composed of S1 + S2 + G structure.

Barbara Ghislain, Julien Engel and Bruno Clair

Edited by Lloyd Donaldson and Pieter Baas

ABSTRACT

Angiosperm trees produce tension wood to actively control their vertical position. Tension wood has often been characterised by the presence of an unlignified inner fibre wall layer called the G-layer. Using this definition, previous reports indicate that only one-third of all tree species have tension wood with G-layers. Here we aim to (i) describe the large diversity of tension wood anatomy in tropical tree species, taking advantage of the recent understanding of tension wood anatomy and (ii) explore any link between this diversity and other ecological traits of the species. We sampled tension wood and normal wood in 432 trees from 242 species in French Guiana. The samples were observed using safranin and astra blue staining combined with optical microscopy. Species were assigned to four anatomical groups depending on the presence/absence of G-layers, and their degree of lignification. The groups were analysed for functional traits including wood density and light preferences. Eighty-six% of the species had G-layers in their tension wood which was lignified in most species, with various patterns of lignification. Only a few species did not have G-layers. We found significantly more species with lignified G-layers among shade-tolerant and shade-demanding species as well as species with a high wood density. Our results bring up-to-date the incidence of species with/without G-layers in the tropical lowland forest where lignified G-layers are the most common anatomy of tension wood. Species without G-layers may share a common mechanism with the bark motor taking over the wood motor. We discuss the functional role of lignin in the G-layer.

Lloyd A. Donaldson, Adya Singh, Laura Raymond, Stefan Hill and Uwe Schmitt

ABSTRACT

Douglas-fir (Pseudotsuga menziesii) has distinctly colored heartwood as a result of extractive deposition during heartwood formation. This is known to affect natural durability and treatability with preservatives, as well as other types of wood modification involving infiltration with chemicals. The distribution of extractives in sapwood and heartwood of Douglas-fir was studied using fluorescence microscopy. Several different types of extractive including flavonoids, resin acids, and tannins were localized to heartwood cell walls, resin canals, and rays, using autofluorescence or staining of flavonoids with Naturstoff A reagent. Extractives were found to infiltrate the cell walls of heartwood tracheids and were also present to a lesser extent in sapwood tracheid cell walls, especially in regions adjacent to the resin canals. Förster resonance energy transfer measurements showed that the accessibility of lignin lining cell wall micropores to rhodamine dye was reduced by about 50%, probably as a result of cell wall-bound tannin-like materials which accumulate in heartwood relative to sapwood, and are responsible for the orange color of the heartwood. These results indicate that micro-distribution of heartwood extractives affects cell wall porosity which is reduced by the accumulation of heartwood extractives in softwood tracheid cell walls.

Lucian Kaack, Clemens M. Altaner, Cora Carmesin, Ana Diaz, Mirko Holler, Christine Kranz, Gregor Neusser, Michal Odstrcil, H. Jochen Schenk, Volker Schmidt, Matthias Weber, Ya Zhang and Steven Jansen

Edited by Lloyd A. Donaldson

ABSTRACT

Pit membranes in bordered pits of tracheary elements of angiosperm xylem represent primary cell walls that undergo structural and chemical modifications, not only during cell death but also during and after their role as safety valves for water transport between conduits. Cellulose microfibrils, which are typically grouped in aggregates with a diameter between 20 to 30 nm, make up their main component. While it is clear that pectins and hemicellulose are removed from immature pit membranes during hydrolysis, recent observations of amphiphilic lipids and proteins associated with pit membranes raise important questions about drought-induced embolism formation and spread via air-seeding from gas-filled conduits. Indeed, mechanisms behind air-seeding remain poorly understood, which is due in part to little attention paid to the three-dimensional structure of pit membranes in earlier studies. Based on perfusion experiments and modelling, pore constrictions in fibrous pit membranes are estimated to be well below 50 nm, and typically smaller than 20 nm. Together with the low dynamic surface tensions of amphiphilic lipids at air-water interfaces in pit membranes, 5 to 20 nm pore constrictions are in line with the observed xylem water potentials values that generally induce spread of embolism. Moreover, pit membranes appear to show ideal porous medium properties for sap flow to promote hydraulic efficiency and safety due to their very high porosity (pore volume fraction), with highly interconnected, non-tortuous pore pathways, and the occurrence of multiple pore constrictions within a single pore. This three-dimensional view of pit membranes as mesoporous media may explain the relationship between pit membrane thickness and embolism resistance, but is largely incompatible with earlier, two-dimensional views on air-seeding. It is hypothesised that pit membranes enable water transport under negative pressure by producing stable, surfactant coated nanobubbles while preventing the entry of large bubbles that would cause embolism.

Jie Wang, Liping Ning, Qi Gao, Shiye Zhang and Quan Chen

Edited by Lloyd A. Donaldson

ABSTRACT

The subject of this study is the structure and composition of buried Phoebe zhennan wood. Through comparative studies of the anatomy and composition with modern undegraded wood, the objective was to understand any changes that have taken place in the P. zhennan buried wood samples. The P. zhennan buried wood can be identified by wood structure characteristics and volatile components analysis. It is required that the microstructural features are identical to those of modern P. zhennan wood; simultaneously, the volatile components of the wood must contain six characteristic compounds with the same peak retention time. The P. zhennan buried wood sample which was used in the experiment was dated 8035–7945 BP (95. 4% probability). Further research showed that the cell wall of P. zhennan buried wood had been damaged, the hemicellulose was heavily degraded but there was no obvious degradation of crystalline cellulose. Moisture was present mainly as free water and large amounts of mineral elements such as Fe, and Ni were detected in the ash of P. zhennan buried wood. Both the buried and modern wood of P. zhennan were acidic.

Shuqin Zhang, Rong Liu, Caiping Lian, Junji Luo, Feng Yang, Xianmiao Liu and Benhua Fei

Edited by Lloyd A. Donaldson

ABSTRACT

The flow of xylem sap in bamboo is closely associated with metaxylem vessels and the pits in their cell walls. These pits are essential components of the water-transport system and are key intercellular pathways for transverse permeation of treatment agents related to utilization. Observations of metaxylem vessels and pits in moso bamboo culm internodes were carried out using environmental scanning electron microscopy (ESEM) to examine mature bamboo fractures and resin casts. The results showed that bordered pits were distributed in relation to adjacent cell types with most pits between vessels and parenchyma cells and few pits between vessels and fibers of the bundle sheath. The pit arrangement was mainly opposite to alternate with apertures ranging from oval, flattened elliptical, or slit-like to coalescent. The vertical dimensions of inner apertures and outer apertures of the pits were about 0.9–2.7 μm and 1.1–3.8 μm, respectively. According to the relative position, and size difference between the inner apertures and their borders, the bordered pit shapes were categorized into three types, namely PI, PII and PIII (Fig. 3C). Half-bordered pit pairs were observed between vessels and direct contact parenchyma cells. Most vessel elements possessed simple perforation plates.

Shahanara Begum, Osamu Furusawa, Masaki Shibagaki, Satoshi Nakaba, Yusuke Yamagishi, Joto Yoshimoto, Md Hasnat Rahman, Yuzou Sano and Ryo Funada

Edited by Lloyd A. Donaldson

ABSTRACT

The aim of the present study was to investigate the orientation and localization of actin filaments and cortical microtubules in wood-forming tissues in conifers to understand wood formation. Small blocks were collected from the main stems of Abies firma, Pinus densiflora, and Taxus cuspidata during active seasons of the cambium. Bundles of actin filaments were oriented axially or longitudinally relative to the cell axis in fusiform and ray cambial cells. In differentiating tracheids, actin filaments were oriented longitudinally relative to the cell axis during primary and secondary wall formation. In contrast, the orientation of well-ordered cortical microtubules in tracheids changed from transverse to longitudinal during secondary wall formation. There was no clear relationship between the orientation of actin filaments and cortical microtubules in cambial cells and cambial derivatives. Aggregates of actin filaments and a circular band of cortical microtubules were localized around bordered pits and cross-field pits in differentiating tracheids. In addition, rope-like bands of actin filaments were observed during the formation of helical thickenings at the final stage of formation of secondary walls in tracheids. Actin filaments might not play a major role in changes in the orientation of cortical microtubules in wood-forming tissues. However, since actin filaments were co-localized with cortical microtubules during the formation of bordered pits, cross-field pits and helical thickenings at the final stage of formation of the secondary wall in tracheids, it seems plausible that actin filaments might be closely related to the localization of cortical microtubules during the development of these modifications of wood structure.

Edited by Editors IAWA Journal

Adya P. Singh, Yoon Soo Kim and Ramesh R. Chavan

Edited by Lloyd A. Donaldson

ABSTRACT

This review presents information on the relationship of ultrastructure and composition of wood cell walls, in order to understand how wood degrading bacteria utilise cell wall components for their nutrition. A brief outline of the structure and composition of plant cell walls and the degradation patterns associated with bacterial degradation of wood cell walls precedes the description of the relationship of cell wall micro- and ultrastructure to bacterial degradation of the cell wall. The main topics covered are cell wall structure and composition, patterns of cell wall degradation by erosion and tunnelling bacteria, and the relationship of cell wall ultrastructure and composition to wood degradation by erosion and tunnelling bacteria. Finally, pertinent information from select recent studies employing molecular approaches to identify bacteria which can degrade lignin and other wood cell wall components is presented, and prospects for future investigations on wood degrading bacteria are explored.

Volker Haag, Gerald Koch, Hans-Georg Richter, Robert Evans, José Antonio Silva Guzmán and Uwe Schmitt

Edited by Lloyd A. Donaldson

ABSTRACT

Anatomical and subcellular characteristics of juvenile and adult wood of seven species (Manilkara zapota (L.) P. Royen, Platymiscium yucatanum Standl., Lonchocarpus castilloi Standl., Roseodendron donnell-smithii (Rose) Miranda, Terminalia buceras (L.) Wright, Tabebuia rosea (Bertol.) DC., Lysiloma latisiliquum (L.) Benth. from Mexico, including a histometric evaluation, were investigated by light microscopy with a digitized image analysis system and by X-ray diffractometry using the SilviScan® system. The topochemical distribution of lignin and phenolic deposits in the tissue was studied by means of cellular UV-microspectrophotometry (UMSP). Extractive contents (acetone/water and water) were determined gravimetrically. The results of the structural and topochemical analyses were compared with the interrelations of certain anatomical and subcellular structures as well as the topochemical composition with regard to the physical and mechanical properties of the timbers investigated. The objective was to provide a detailed cellular and subcellular description of the heartwood of seven lesser-known timbers from Central America. All examined tree species show significant differences between juvenile and adult heartwood. For individual species, however, the differences vary greatly and have to be individually assessed in addition to general trends observed for all studied species. It has been shown that vessel size, fibre length, size of fibre lumina, and height and width of rays, as well as the content of extractives and topochemical composition of the cell walls, are suitable indicators for the differentiation of the two heartwood types. The results also contribute to a better understanding of the wood properties of the investigated timbers in relation to their utilization and added value increase.

Edited by Lloyd A. Donaldson and Pieter Baas

Lloyd A. Donaldson

Edited by Pieter Baas

ABSTRACT

In the last 100 years, major advances have been made in understanding wood cell wall ultrastructure in tracheids, fibres, vessels and parenchyma and its relationship with xylem function and wood properties. This review will focus on how the development of imaging techniques and their application to wood cell walls has led to an understanding of cell wall organisation and the relationship between micro and macro scale properties in wood and wood-based materials. Topics such as wood formation, wood chemistry and reaction wood have recently been reviewed elsewhere and are considered only briefly in this review. Two features of wood cell walls have dominated the literature; orientation and layering of cellulose which determines the longitudinal stiffness of wood, and the distribution (topochemistry) of lignin which determines compression strength and pulping properties.

Editors IAWA List of Microscopic Bark Features

Patrik Ahvenainen

ABSTRACT

Many endangered tropical hardwoods are commonly used in electric guitars. In order to find alternative woods, the current electric guitar woods need to be studied and classified as most research in this field has focused on acoustic instruments. Classification was done based on luthier literature, woods used in commercially available electric guitars, commercially available tonewoods and by interviewing Finnish luthiers. Here, the electric guitar woods are divided into three distinct classes based on how they are used in the guitar: low-density wood used in the body only (alder, poplar, basswood, ash), medium-density wood used in the body and neck (maple and mahogany), and high-density wood used in the fretboard only (rosewood and ebony). Together, these three classes span a wide range of anatomical and mechanical properties, but each class itself is limited to a relatively narrow parameter space. Statistically significant differences between these classes and the average hardwoods exist in the wood anatomy (size and organization of vessels, fibres, rays and axial parenchyma), in the mechanical properties (density, elastic modulus, Janka hardness, etc.) and in the average price per volume. In order to find substitute woods for a certain guitar wood class, density and elastic modulus can already be used to rule out most wood species. Based on principal component analysis of the elastomechanical and anatomical properties of commercially available hardwoods, few species are similar to the low- and high-density class woods. However, for all of the three electric guitar wood classes, non-endangered wood species are already commercially available from tonewood retailers that match the class characteristics presented here.

Stéphanie C. Bodin, Rita Scheel-Ybert, Jacques Beauchêne, Jean-François Molino and Laurent Bremond

ABSTRACT

Tropical tree floras are highly diverse and many genera and species share similar anatomical patterns, making the identification of tropical wood charcoal very difficult. Appropriate tools to characterize charcoal anatomy are thus needed to facilitate and improve identification in such species-rich areas.

This paper presents the first computer-aided identification key designed for charcoals from French Guiana, based on the wood anatomy of 507 species belonging to 274 genera and 71 families, which covers respectively 28%, 67% and 86% of the tree species, genera and families currently listed in this part of Amazonia. Species of the same genus are recorded together except those described under a synonym genus in Détienne et al. (1982) that were kept separately. As a result, the key contains 289 ‘items’ and mostly aims to identify charcoals at the genus level. It records 26 anatomical features leading to 112 feature states, almost all of which are illustrated by SEM photographs of charcoal. The descriptions were mostly taken from Détienne et al.’s guidebook on tropical woods of French Guiana (1982) and follow the IAWA list of microscopic features for hardwood identification (Wheeler et al. 1989). Some adjustments were made to a few features and those that are unrelated to charcoal identification were excluded. The whole tool, named CharKey, contains the key itself and the associated database including photographs. It can be downloaded on Figshare at https://figshare.com/s/d7d40060b53d2ad60389 (doi: 10.6084/m9.figshare.6396005). CharKey is accessible using the free software Xper2, specifically conceived for taxonomic description and computer aided-identification.

Pieter Baas and Elisabeth Wheeler

Oliver Dünisch

ABSTRACT

The relationship between the spatial organization of different cell types, of the xylem rays, and of the tree rings and the frequencies in vibrating softwoods and hardwoods was studied under controlled conditions. In total, the frequencies in 1007 standardized vibrating plates from 16 softwoods and 74 hardwoods were analysed using high resolution laser sensors (accuracy ± 0.02 μm, sampling frequency 30 kHz) for vibration measurements. Overlapping frequencies within the frequency spectra were identified by means of Fast Fourier Transformation analysis. With regard to the number of distinct frequencies within the spectra, four different vibration types were identified: type 1–one dominant frequency within the frequency spectra; type 2-two dominant frequencies within the frequency spectra; type 3-three dominant frequencies within the frequency spectra; type 4-no dominant frequencies within the frequency spectra. The presence of distinct frequencies was correlated with a highly organized spatial arrangement of tracheids in softwoods, with a storied arrangement of the xylem rays in hardwoods, and with low variation in tree-ring width in both softwoods and hardwoods. The grid size for repetition in these xylem structures influenced the frequencies of the vibrating wood in absolute numbers. The results indicate that the analysis of the anatomical structure of the wood can contribute to the grading of timber for its vibration characteristics, which is of special interest for the selection of resonance wood for musical instruments.

Anna L. Jacobsen, R. Brandon Pratt, Martin D. Venturas and Uwe G. Hacke

Associate-editor Frederic Lens

ABSTRACT

Xylem vessels interconnect to form the vessel network that is responsible for long-distance water transport through the plant. As plants dehydrate, the water column within vessels cavitates and gas emboli form, which block transport through embolized vessels. The impact of vessel blockages on transport through the xylem tissue depends upon vessel size and the arrangement and connections between vessels in the network. We examined if there was a correlation between vessel length and diameter within poplar stem xylem tissue using both silicone-injection and analysis of tissue volumes scanned using high-resolution computed tomography (microCT). We then used microCT to scan intact stems sampled over varying water potentials to examine if larger vessels, which would have the greatest impact on hydraulic transport, were more vulnerable to cavitation and embolism than smaller vessels. Within the xylem tissue, larger diameter vessels tended to be longer than narrow diameter vessels. Vessel size distributions indicated that most vessels were narrow and short, with fewer large vessels. Larger volume vessels tended to embolize at higher water potentials and the mean vessel volume of embolized vessels declined as water potentials declined. Hydraulic transport through the xylem tissue was near zero when about 40% of the vessels within the xylem tissue volume were embolized, suggesting important vessel network effects occur as water moves through a three-dimensional (3D) tissue. The structure of the vessel network is important in understanding the impact of emboli within vessels on the overall hydraulic function of xylem tissue.

Bei Luo, Tomoya Imai, Junji Sugiyama and Jian Qiu

ABSTRACT

Agarwoods such as Aquilaria spp. and Gyrinops spp. (Thymelaeaceae) produce interxylary phloem in their secondary xylem and intraxylary phloem at the periphery of the pith, facing the primary xylem. We studied young shoots of Aquilaria sinensis and characterized the development of its intraxylary phloem. It was initiated by the division of parenchyma cells localized in the outer parts of the ground meristem immediately following the maturation of first-formed primary xylem. Its nascent sieve plates bore donut-like structures, the individual pores of which were so small (less than 0.1 μm) that they were hardly visible under FE-SEM. Intraxylary phloem developed into mature tissue by means of the division and proliferation of parenchyma cells. During the shoots’ active growth period, the sieve pore sizes were 0.1–0.5 μm, with tubular elements passing through them. In the maturation stage, large clusters of sieve tubes continued to be differentiated in the intraxylary phloem. In the partial senescence stage observed in a three-centimeter-diameter branch, intraxylary phloem cells in the adaxial part became crushed, and sieve plates had pores over 1–2 μm in diameter without any callose deposition. Before and after the differentiation of interxylary phloem in the first and second internodes, callose staining detected more than twice as many sieve tubes in intraxylary phloem than in external phloem. However, after differentiation of interxylary phloem in the eleventh internode, more sieve tubes were found in interxylary phloem than in intraxylary and external phloem. This suggests that prior to the initiation of interxylary phloem intraxylary phloem acts as the principal phloem. After its differentiation, however, interxylary phloem takes over the role of principal phloem. Interxylary phloem thus acts as the predominant phloem in the translocation of photosynthates in Aquilaria sinensis.

Kelly Cristina Moreira dos Santos, Gabriel Uriel Cruz Araújo dos Santos, Claudia Franca Barros, Haroldo Cavalcante de Lima and Cátia Henriques Callado

ABSTRACT

Stryphnodendron Mart. is a widespread genus in the Neotropics and its species are widely used for their timber, in popular medicine, and for tanning. The similarities in their external morphology make species identification difficult in this genus. This study describes and compares the wood anatomy of the seven species of Stryphnodendron most frequently found in Brazilian forest remnants, in order to identify which anatomical features can be used in their segregation. From seven species 31 samples of Stryphnodendron were studied. Principal Component Analysis was used to evaluate wood anatomical characters. The species were separated into two main groups, congruent with the division into multifoliolate and paucifoliolate species, due to the presence of diffuse, lozenge-aliform and confluent axial parenchyma. In the multifoliolate group, although two subgroups were formed due to ray width in number of cells, none of the species were individualised, which corroborates previous findings of high morphological and anatomical similarities of the multifoliolate species.

Maomao Zhang, Guang Jie Zhao, Bo Liu, Tuo He, Juan Guo, Xiaomei Jiang and Yafang Yin

ABSTRACT

Pterocarpus santalinus, listed in CITES Appendix II, is an endangered timber species as a result of illegal harvesting due to its high value and commercial demand. The growing demand for P. santalinus and timbers with the morphologically similar Pterocarpus tinctorius has resulted in confusion as well as identification problems. Therefore, it is of vital importance to explore reliable ways to accurately discriminate between P. santalinus and P. tinctorius. In this study, the method of direct analysis in real time and fourier transform ion cyclotron resonance mass spectrometry (DART-FTICR-MS), combined with multivariate statistical analysis, was used to extract chemical information from xylarium wood specimens and to explore the feasibility of distinguishing these two species. Significant differences were observed in their DART-FTICR-MS spectra. Orthogonal partial least square-discriminant analysis (OPLS-DA) showed the highest prediction, with an accuracy of 100%. These findings demonstrate the feasibility of authenticating wood types using DART-FTICR-MS coupled with multivariate statistical analysis.

Tomáš Kolář, Vladimír Gryc, Konrad Mayer, Michal Rybníček, Hanuš Vavrčík, Andrea Weber and Michael Grabner

Associate-editor Shuichi Noshiro

ABSTRACT

Hand spinning has become increasingly popular as a recovery of the traditional techniques of natural fibre processing and cultural heritage protection. Modern spinning wheels are usually made of easily available wood species, particularly hardwoods, and one spinning wheel usually consists of one or two species. However, the wood species that were used for the individual parts of old spinning wheels in Central Europe are still unknown. To improve our understanding of traditional craftsmen and their skills, we investigated old spinning wheels that originated from Central Europe in the 19th and the 20th century. In this study, we present a collection of 643 samples from 54 artefacts representing the region between the European Alps and the Western Carpathians. Spinning wheels were usually made of 3 to 5 wood species, and the species selection varied among regions. Generally, high wood density (> 600 kg.m−3) species prevailed in Austria and Western Slovakia, but lower wood density (< 600 kg.m−3) species were preferred in the south-eastern Czech Republic. Easily workable species were used for the production of the spinning wheels, primarily Tilia, Fagus sylvatica, Picea abies, and Acer. In addition to these species, a high proportion of fruit-bearing trees and three shrubs were identified. Wood anatomy, as an important scientific method, contributed to understanding the reasons for species selection and the suitability of their properties which will enable the conservation of sustainable folk traditions and crafts, as well as the knowledge of traditional craftsmen.

Anna Dinella, Francesco Giammarchi and Giustino Tonon

Edited by Veronica De Micco

ABSTRACT

Peatland ecosystems are an important archive of paleoclimatic information. Within this context, tree-ring data from trees growing in such ecosystems are extremely valuable resources, and subfossil trees from peat bogs have been widely employed in dendroclimatological studies. However, there are still gaps in our understanding of the relationships among tree growth, peatland hydrology and climate factors. Here, we summarize the principal studies on living peatland trees, with a particular focus on their use as a source of information on past climatic conditions. We discuss the main factors influencing tree growth in this environment, whether it is the local hydrological cycle or climate. We put a particular focus on the reliability of the climate signal recorded by living peatland trees, comparing it with that found in subfossil trees. Finally, we discuss the relevance of quantitative wood anatomy in the context of peatland ecosystems research.

Larissa C. Dória, Diego S. Podadera, Rivete S. Lima, Frederic Lens and Carmen R. Marcati

Edited by Marcelo R. Pace

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.

Marcos González-Cásares, Marín Pompa-García and Alejandro Venegas-González

ABSTRACT

Ongoing climate change is expected to alter forests by affecting forest productivity, with implications for the ecological functions of these systems. Despite its great dendrochronological potential, little research has been conducted into the use of wood density as a proxy for determining sensitivity to climate variability in Mexico. The response of Abies durangensis Martínez, in terms of wood density and growth ring width, to monthly climatic values (mean temperature, accumulated precipitation and the drought index SPEI) was analyzed through correlation analysis. Abies durangensis presents a high response, in terms of radial growth, to climatic conditions. Tree-ring widths are more sensitive to hydroclimatic variables, whereas wood density values are more sensitive to temperature. In particular, mean (MeanD) and minimum (MND) wood density values are more sensitive to climate than maximum (MXD). We found very marked spatial variations that indicate that A. durangensis responds differently to drought conditions depending on the indices of density.

Junji Luo, Rong Liu, Shuqin Zhang, Caiping Lian, Feng Yang and Benhua Fei

Abstract

Not only are vessel pits vital for the passage of sap into adjacent cells, but their anatomical morphology is also used as a tool to identify bamboo species. However, detailed studies comparing the pits’ structural parameters in culms of species with three rhizome types: sympodial bamboo, amphipodial bamboo, and monopodial bamboo, are lacking. Scanning electron microscopy (SEM) observations were conducted to obtain the qualitative and quantitative characteristics of vessel pits in sympodial, amphipodial and monopodial bamboos, from twelve bamboo species in eight genera. Sympodial bamboos possess small and ovoid bordered pits, whereas amphipodial bamboos contain an abundance of slit-like pits, with the greatest pit membrane length occurring in the vessel wall. Both minute and large pit sizes can be found in monopodial bamboos. This study identified the first compound pits ever to be found in a bamboo species and these were found to occur more frequently in amphipodial and monopodial bamboos than in sympodial bamboos. Using the distribution frequency of the pit chamber’s horizontal diameter, we were able to determine pit size as being either small, medium or large. The striking differences in the vessel pits’ qualitative and quantitative characteristics could be the result of different climate and environmental factors.

C. Alvites, G. Battipaglia, G. Santopuoli, H. Hampel, R.F. Vázquez, G. Matteucci and R. Tognetti

Edited by Veronica De Micco

ABSTRACT

Relict tree species in the Andean mountains are important sources of information about climate variability and climate change. This study deals with dendroclimatology and growth patterns in Polylepis reticulata Hieron., growing at high elevation (mean of 4000 m a.s.l.) in three sites of the Ecuadorian Andes. The aims of the research were: (i) characterizing tree-ring boundaries; (ii) describing tree-ring patterns of the study sites; (iii) investigating the relationships between climate and radial tree growth; and (iv) determining the spatial correlation between seasonal climatic factors and tree-ring width of P. reticulata. Tree rings were characterized by semi-ring porosity and slight differences in fibre wall thickness between latewood and subsequent earlywood. In all sampling sites, tree rings in heartwood were more clearly visible than in sapwood. Tree-ring width was more related to temperature than to precipitation, with growth being also affected by site conditions and stand structure, as well as other local factors. No significant relationships were found between tree-ring chronologies of P. reticulata and El Niño-Southern Oscillation (ENSO) and Vapour Pressure Deficit indices. The study highlights that there is not a clear driving climate factor for radial growth of P. reticulata. Additional research is needed to study growth dynamics of this species and the impacts of local environmental variables.

Adam Miodek, Aldona Gizińska, Marcin Klisz, Tomasz Wojda, Krzysztof Ukalski and Paweł Kojs

Abstract

Our study investigated the effect of stem temperature increase on xylem formation in Robinia pseudoacacia tree-trunks, caused by direct exposure to solar radiation. It is important to determine factors which may improve the concentricity of deposited wood tissue and intensify xylogenesis because a strong irregularity of wood tissue deposited in the radial direction in mature trees of R. pseudoacacia reduces the commercial value of the wood. Samples of vascular cambium along with adjacent tissues were collected from the southern (illuminated) and northern (shaded) side of tree-trunks growing in the inner and peripheral (thus exposed to direct sunlight) zones of the research plot. Sampling was performed several times during the growing season. The collected material was examined by epifluorescence microscopy and the thickness of deposited tissue comprising cambial xylem derivatives was measured. Deposition of a markedly greater amount of xylem on the southern side of tree-trunks in the peripheral zone of the plot was observed before full leaf development. Instrumental climatic data confirmed that in the early stage of the growing season, temperature on the southern side of the peripheral zone tree-trunk was higher than on the northern side. No clear response in terms of directional deposition of xylem was noticed in the inner zone trees and in peripheral zone trees after full leaf development. This study highlights the importance of temperature increase, caused by solar radiation, for R. pseudoacacia xylogenesis, which may be considered as a factor that affects the course of the radial growth before full leaf development.

Murat Ozturk, Kadir Alperen Coskuner, Yetkin Usta, Bedri Serdar and Ertugrul Bilgili

ABSTRACT

Mistletoes are hemi-parasitic plants growing on many tree species. They grow on the tree branches or trunk of a tree and form root-like structures called haustoria that penetrate into the tree, taking up water and mineral nutrients. Mistletoe is capable of causing a variety of effects to its hosts, including changes in wood formation and leaf development. We investigate and discuss the effects of pine mistletoe (Viscum album ssp. austriacum, Santalaceae) on branch wood and needle anatomy of Scots pine (Pinus sylvestris, Pinaceae). Parasitized and nonparasitized branches of Scots pine were sampled from host tree crowns of trees growing on the same site. Branches were taken from mid-crown facing south. They were cut at 2 cm proximal and 2 cm distal to the mistletoe on each host branch and at the corresponding position in the case of uninfected branches from the same host. The wood anatomy at proximal and distal parts and the parts at the corresponding position in the non-parasitized section was compared. The anatomy of one-year-old needles from both parasitized and non-parasitized branches was also compared. Mistletoe had significant influences on wood and needle anatomy. The major changes were the decreases in the double wall thickness, lumen area, tangential lumen area and radial lumen area of the tracheids in the wood and a decrease in vascular area in the needles. These results help to understand how mistletoe acts on its host.

Veronica De Micco, Marco Carrer, Cyrille B.K. Rathgeber, J. Julio Camarero, Jordi Voltas, Paolo Cherubini and Giovanna Battipaglia

ABSTRACT

It is noteworthy that the largest part of global vegetation biomass depends on a thin layer of cells: the vascular cambium. Understanding the wood formation processes and relationships with environmental factors is a crucial and timely research question requiring interdisciplinary efforts, also to upscale the information gained and to evaluate implications for tree growth and forest productivity.

We provide an overview of wood formation processes up to tree-ring development, bearing in mind that the combined action of intrinsic factors and environmental drivers determines the anatomical traits of a tree ring formed at a specific time and position within the tree’s architecture. After briefly reviewing intrinsic factors, we focus attention on environmental drivers highlighting how a correct interpretation of environmental signals in tree rings must be grounded in a deep knowledge of xylogenesis and consequent wood anatomical traits. We provide guidelines on novel methods and approaches recently developed to study xylem formation. We refer to existing literature on established techniques for retrospective analyses in tree-ring series of anatomical and isotopic traits, to assess long-term ecophysiological responses to environmental variations, also giving advice on possible bias because of interand within-tree variability.

Finally, we highlight that, once the temporal axis of intra-annual tree-ring variability of xylem traits is established by xylogenesis analysis, a multidisciplinary approach linking classical dendro-ecology, wood functional traits (dendro-anatomy) and eco-physiology (here focusing on dendro-isotopes) allows a better interpretation of past environmental events hidden in tree rings, and more reliable forecasts of wood growth in response to climate change.

Serena Antonucci, Sergio Rossi, Fabio Lombardi, Marco Marchetti and Roberto Tognetti

ABSTRACT

Xylem phenology has been widely recognised as an ecological indicator of the impact of environmental changes on forest ecosystems, especially at the edge of a species distribution. We investigated xylem phenology of silver fir (Abies alba Mill.) in three sites in Italy, between the 38th and 46th parallels. The phases of xylem phenology were assessed weekly on wood microcores collected from March to November 2015 to calculate timing and duration of xylem cell production. The effect of temperature and precipitation on xylem phenology were sequentially included in stepwise regressions and used to predict the duration of each phenological phase under three future climatic scenarios at different concentrations of greenhouse gases (RCP 2.6; 4. 5; 8. 5). A growing season of 163 days was detected in the southern site that was longer compared to the central (132 days) and northern (120 days) sites. A longer duration of xylogenesis was mostly related to a delayed completion of xylem differentiation in autumn rather than an earlier onset of cambium reactivation in spring. Overall, 67–76% of the duration of phenological phases was controlled by growing season precipitation, while 24 –33% was influenced by minimum temperature. Inclusion of both the above factors in the modelling exercise simulated a lengthening of the silver fir growing season during the 21st century. A longer duration of xylogenesis was envisaged in the scenario RCP 8. 5, especially in the central site. Population and climate gradients need to be considered when addressing phenological shifts and growth dynamics of silver fir in Mediterranean mountains.

J. Julio Camarero

Edited by Victoria De Micco

ABSTRACT

Functional traits are considered to influence the performance of woody plants. However, few field studies have tested this idea by using radial-growth data. Here, I test if five major traits of the leafand wood-economics spectra (height, leaf area, specific leaf area – SLA, wood density – WD and hydraulic diameter) explain climate-growth relationships in 14 Mediterranean trees and shrubs. Traits were measured for both gymnosperm (four Juniperus species plus three Pinus species) and angiosperm species (two Quercus species, two Pistacia species, Arbutus unedo, Celtis australis, and one Tamarix species). Climategrowth relationships were calculated relating ring-width indices (RWIs) and local climate data. Leaf area and SLA were high in broadleaf deciduous species (e.g., C. australis), and low in junipers. WD reached minimum and maximum values in pine and oak species, respectively. WD explained 45 % of the variation of the association observed between RWI and April precipitation, one of the main climatic variables driving radial growth. Therefore, WD is a relevant functional trait useful to predict the performance of Mediterranean woody plant species, specifically concerning their growth responses to climate. Functional traits as WD should be further explored to explain growth variability between and within woody species, and to link this variability with responsiveness to climate and ecosystem productivity.

Robin Adey-Johnson, J. Paul Mclean, Jan Van den Bulcke, Joris Van Acker and Peter J. McDonald

Abstract

This study aimed to define the variability in the microstructure of Norway spruce within an annual ring by examining differences between earlywood and latewood. In particular, we were interested in obtaining new information on bordered pit occurrence and locations relative to tracheid ends, plus the lumina dimensions and longitudinal overlap of tracheids that collectively define the longitudinal hydraulic pathways. A stacked series of X-ray micro-CT scans of an annual ring of Norway spruce were made and stitched together longitudinally to form a three-dimensional volume. The imaging resolution was carefully chosen to capture both longitudinal and transverse anatomical details. Measurements of tracheid length, overlap, radial lumen diameter, and bordered pit location were made semi-automatically using image analysis. The distribution of radial lumen diameter was used to define earlywood and latewood. Then bordered pit linear density and spatial distribution, tracheid length and overlap were analysed, presented and contrasted for earlywood and latewood. Further differences between earlywood and latewood were found only in bordered pit linear density. Clear trends in radial lumen diameter and pit linear density were observed with radial position within the growth ring. These results provide new information on the variability of the Norway spruce microstructure within an annual ring.

Bei Luo, Tomoya Imai, Junji Sugiyama, Sri Nugroho Marsoem, Tri Mulyaningsih and Takao Itoh

Abstract

New observations of radial sieve tubes in the secondary xylem of two genera and four species of agarwood — Aquilaria sinensis, A. crasna, A. malaccensis and Gyrinops versteeghii (Thymelaeaceae) — are presented in this study. The earliest radial sieve tubes in Gyrinops are formed in the secondary xylem adjacent to the pith. The radial sieve tubes originate from the vascular cambium and develop in both uniseriate and multiseriate ray tissue. In addition to sieve plates in lateral and end walls, scattered or clustered minute sieve pores are localized in the lateral wall of radial sieve tubes. There is a direct connection between radial sieve tubes in ray tissue and axial sieve tubes in interxylary phloem strands (IP), such as (i) connection by bending of radial sieve tube strands, (ii) connection of two IP strands by an oblique bridge, and (iii) connection of two IP strands at a right angle. The average number of radial sieve tubes and interxylary phloem was found to be 1.7 per mm3 and 9.1 per mm2 in the secondary xylem. Considering the higher frequency of radial sieve tubes with the increasing thickness of the secondary xylem, the direct connections between radial and axial sieve tubes could play a significant role in assisting the translocation of metabolites in Aquilaria and Gyrinops.

Edited by Veronica De Micco, Giovanna Battipaglia, J. Julio Camarero, Chiara Cirillo and Pieter Baas

Maxmira de Souza Arêdes-dos-Reis, Monique Silva Costa, Gabriel Uriel Cruz Araújo dos Santos and Cátia Henriques Callado

ABSTRACT

Radial growth dynamics of woody species is studied by different methods. the annual monitoring of cambial activity has been recommended as the method of greatest accuracy in research and appropriate for studies in protected areas for biological conservation, because it is largely nondestructive. Nevertheless, sampling protocols still need more standardization and precision. this study aims to investigate the influence of cardinal orientation on the number of cells in the cambial zone, and to evaluate the number of trees needed to conduct histological studies of cambial activity in Cedrela odorata, a tropical species with well-defined annual growth in the Atlantic Forest of South America/Brazil. Seventeen trees were evaluated during the period of intense cambial activity, with the sampling of four quadrants of the stem, according to cardinal orientation. the variance of cambial cell numbers was calculated for different numbers of trees. the results showed that radial growth variance was not related to cardinal orientation, but that at least 12 trees should be sampled for robust data on cambial dynamics.

Andrea Cecilia Acosta-Hernández, J. Julio Camarero and Marín Pompa-García

ABSTRACT

Warming-amplified drought stress may decrease productivity and growth in both wet and dry conifer forest ecosystems. However, the seasonal radial-growth responses to climate, drought and related climate atmospheric patterns have not been compared in detail in wet and dry sites. We focus on drought-prone northern Mexico conifer forests and compare growth responses in tree species from wet (Pseudotsuga menziesii) and dry sites (Pinus leiophylla). to characterize the responsiveness to interand intra-annual changes in water availability we used dendrochronology and measured tree-ring (TRW), earlywood (EW) and latewood (LW) widths. We calculated adjusted LW (LWadj) by removing the influence of EW on LW. We identified E(narrow tracheids within the earlywood) and L-type (wide tracheids within the latewood) intra-annual density fluctuations (IADFs) and related their frequencies to seasonal climate and drought. We also related growth to atmospheric patterns related to the El NiñoSouthern Oscillation (ENSO) which drives precipitation patterns in the studied region. Wet-cool conditions during the prior winter and current spring linked to El Niño events enhanced TRW and EW, particularly in P. menziesii, whereas wet summer conditions enhanced LWadj. The formation of E(P. leiophylla) and L-type (P. menziesii) IADFs was associated with seasonal fluctuations in precipitation and temperature, suggesting different strategies to withstand drought. the sensitive P. menziesii strongly responded to short spring droughts, whereas the tolerant P. leiophylla responded to longer spring droughts. Seasonal wood measures (EW, LWadj) and IADFs are proxies of intra-annual fluctuations in water availability in similar conifer forests.

Saskia Luss, Sven-Olof Lundqvist, Robert Evans, Thomas Grahn, Lars Olsson, Giai Petit and Sabine Rosner

ABSTRACT

Relationships between hydraulic vulnerability expressed as P 50 (the air pressure causing 50% loss of hydraulic conductivity) and within-ring differences in wood density (WD) and anatomical features were investigated with the aim to find efficient proxies for P 50 relating to functional aspects. WD and tracheid dimensions were measured with SilviScan on Norway spruce (Picea abies (L.) Karst.) trunk wood.

P 50 was strongly related to mean WD (r = -0.64) and conduit wall reinforcement ((t/b)2), the square of the ratio between the tracheid double wall thickness (t) and the lumen width (b), where use of tangential lumen width ((t/b t)2) gave better results (r = -0.54) than radial lumen width (r = -0.31). The correlations of P 50 with earlywood (EW), transition wood (TW) and latewood (LW) traits were lower than with the specimen averages, both for WD (r = -0.60 for WDEW, r = -0.56 for WDTW, r = -0.23 for WDLW) and all anatomical traits. The loss of hydraulic conductivity was addressed as a dynamic process and was simulated by defining consecutive phases of 5% theoretical conductivity loss. WD and tracheid traits were calculated and correlated with P 50 values of each specimen. Tightest correlations were found for (t/b t)2, at relative cumulated theoretical conductivities until 45 to 50% (r = -0.75).

We conclude that WD is one of the best available proxies for P 50, but does not necessarily reflect the mechanism behind resistance to cavitation. The new trait, based on estimation of conductivity loss as a dynamic process, provided even stronger correlations.

Thaís Jorge de Vasconcellos and Cátia Henriques Callado

Abstract

Urban pollution is one of the current environmental problems which most threatens the human and environmental health. In a fast-changing world, trees stand out among the sessile organisms that withstand the variations imposed by the environment throughout their lifespan. Thus, trees have become important objects of study in the evaluation of phenological, physiological and/or morphological plasticity. Previous studies have demonstrated the impact of urban environment on cambium anatomy and dendrochronology of Ceiba speciosa (Malvaceae), a native species of the Atlantic Forest. In the present study, our objective is to evaluate the impact of the urban environment on wood structure and consequently on the hydraulic architecture of Ceiba speciosa. Wood samples were collected by a non-destructive method, processed and analyzed according to the usual techniques for plant anatomy. Samples were collected in two sites: the first, an important forest remnant of the Atlantic Forest, and the second next to Avenida Brasil, the largest avenue in Rio de Janeiro, the fourth largest city in Latin America. Trees showed plasticity in seven anatomical features and significant differences in wood structure between both groups studied. Urban trees have lower hydraulic conductivity, shorter vessels and fibres, and larger, more frequent rays. These features demonstrate that in stressful situations, such as those observed in urbanized environments, Ceiba speciosa invests in more safety for water transport and in lower wood resistance, with a trade-off between high production of cells of low energy cost and providing storage of water and metabolic products for unfavorable periods.

Angela Balzano, Giovanna Battipaglia and Veronica De Micco

ABSTRACT

Mediterranean trees and shrubs form intra-annual density fluctuations (IADFs) in tree rings as a sign of their plasticity in wood formation in response to intraseasonal variations of environmental conditions. Different species show a different aptitude to form IADFs, due to their diverse ability to cope with climate stressors, since the occurrence of IADFs may affect plant hydraulics. Dendroecology and quantitative wood anatomy were used to characterise IADFs in Pinus pinea and Arbutus unedo co-occurring at a Mediterranean site in Italy. The relations between climate parameters (i.e. temperature and precipitation) and intra-annual tree-ring traits (i. e. IADF frequency and conduit size) were analysed to highlight the main triggers for IADF formation and their functional role.

Data showed that both species are characterised by a high plastic response to climate and formed a high frequency of L-IADFs (occurrence of earlywoodlike conduits in latewood). The two species, although forming the same type of IADFs, showed different sensitivity to environmental factors. Pinus pinea showed a high dependence of tracheid size on temperature, while Arbutus unedo was more sensitive to precipitation in spring and autumn. Arbutus unedo promptly developed more than one IADF per year in response to rainfall events following drought periods.

The overall results were useful to compare the aptitude of the two species in forming IADFs and to highlight the factors priming their formation. This is useful to understand wood growth reactions to environmental drivers and to evaluate the adaptive capabilities in these two species, and thus to predict forest reactions after climate changes.

Brett A. Bergman, Edward G. Bobich, Stephen D. Davis, Yasuhiro Utsumi and Frank W. Ewers

ABSTRACT

A node is the point of attachment of the leaf to the stem of a plant; gaps associated with nodes have been viewed as discontinuities of the stem vascular system. We tested the hypothesis that the node/gap is a spring-like joint that impacts stem flexibility even well after the leaves have been shed, with some stems specialized for elongation and others for flexibility. Four-point bending tests were done using an Instron Mechanical Testing Device with the independent variable being the number of nodes in the stem segment and dependent variables being Modulus of Elasticity (MOE), Modulus of Rupture (MOR), and xylem density. Node anatomy was examined microscopically to assess structure and function. The stiffness of the stem was inversely proportional to the frequency of leaf nodes. Surprisingly, xylem density was inversely proportional to the frequency of leaf nodes in stems of adult trees. The tissue around nodes/gaps consisted of twisted and contorted cells that may be effective at absorbing compressive and tensile stresses. Because nodes behave as spring-like joints, the frequency of nodes relates to function, with some stems specialized for vertical expansion and others for light capture and damping of wind stress. The ultimate stems on a tree are the most bendable, which may allow the trees to avoid breakage.

Md Hasnat Rahman, Kayo Kudo, Shahanara Begum, Yusuke Yamagishi, Takahiro Muraishi, Satoshi Nakaba, Yuichiro Oribe, Chanhui Lee, Hyun-O Jin and Ryo Funada

Edited by Lloyd Donaldson

ABSTRACT

To understand the precise process of wood formation, it is necessary to identify the factors that regulate cambial activity and development of cambial derivatives. Here, we investigated the combined effects of localized-heating and auxin on cambial reactivation and the formation of earlywood tracheids in seedlings of the evergreen conifer Abies homolepis in winter. Three treatments were applied, namely heating (artificial increase in temperature 20–22 °C), heating-plus-auxin transport inhibitor N-(1-naphthyl) phthalamic acid (NPA) and heating-plus-defoliation (removal of needles and buds), with an approximate control, for investigations of cambial activity by light microscopy. After one week of heating, cambial reactivation occurred in the heating, heating-plus-NPA and heating-plus-defoliation treatments. In untreated controls, cambial reactivation occurred later than in heated stems. Earlywood tracheids were formed after three and six weeks of heating in the heating and heating-plus-NPA treatments, respectively. No tracheids were formed after eight weeks of heating in heated-defoliated seedlings. Numbers of new tracheids were reduced in heated stems by NPA. Our results suggest that an increase in the temperature of the stem is one of the most important limiting factors in cambial reactivation, which is independent of needles and buds and of the polar transport of auxin from apical sources. However, after cambial reactivation, initiation and continuous formation of earlywood tracheids require basipetally transported auxin and other endogenous factors originating in mature needles and buds.

Marcin Klisz, Adam Miodek, Paweł Kojs and Holger Gärtner

Edited by Veronica de Micco

ABSTRACT

The use of automated techniques for image analysis of microscopic wood specimens together with new procedures for the preparation of stained xylem tissue support the use of quantitative wood anatomy. These techniques and procedures are especially useful in the studies of retrospective analysis of xylem phenology, reaction(s) of trees to stressful conditions of growth, or reconstruction of long-term growth trends. The unresolved technical problems during the digitalization of cross sections from entire increment cores were stabilization and precise shifting of long microscopic specimens onto the optical microscope stage. For this reason, we have developed a long slide holder for microscope stages in two versions: the basic one allowing stabilization and manual shifting, and the advanced one for stabilization and mechanical shifting. Both versions of the adapter speed up the work with long slides, improving the quality of panoramic images of microscopic specimens.

Ye-Ming Cheng, Yu-Fei Wang, Feng-Xiang Liu, Yue-Gao Jin, R. C. Mehrotra, Xiao-Mei Jiang and Cheng-Sen Li

Edited by E.A. Wheeler

ABSTRACT

The Pliocene fluvio-lacustrine sediments of the Yuanmou Basin, Yunnan, near the southeastern part of Qinghai-Tibet Plateau, China, have yielded diverse and abundant assemblages of fossilized mammals and woods. The Yuanmou fossil woods reveal a wood flora with the highest diversity in the Cenozoic wood in China. The woods can play an important role in understanding palaeofloristics and in reconstructing palaeoclimate of southeastern China. In this study, we describe ten angiosperm taxa and three gymnosperm taxa namely: Castanopsis makinoi (Ogura) Suzuki & Terada (Fagaceae), Cedreloxylon cristalliferum Selmeier (Meliaceae), Dalbergioxylon biseriatensis sp. nov. (Fabaceae), Lagerstroemioxylon yuanmouensis Cheng, Li, Jiang & Wang (Lythraceae), Lithocarpoxylon microporosum sp. nov., Lithocarpoxylon sp. (Fagaceae), Paraalbizioxylon sinica sp. nov., P. yunnanensis sp. nov. (Fabaceae), Pterocaryoxylon huxii sp. nov. (Juglandaceae), Zelkova wakimizui (Watari) Watari (Ulmaceae), Abies sp. (Pinaceae), Cephalotaxus sp. (Cephalotaxaceae), and Picea sp. (Pinaceae). Nearest living relative (NLR) comparisons of these taxa, coupled with previously identified taxa, suggest that altitudinal vegetation zones were present in the Yuanmou region during the Pliocene: (i) subtropical evergreen and deciduous mixed broad-leaved forest dominated by Pterocarya/Juglans, Albizia/Acacia, Bischofia and allied taxa at lower elevations, (ii) subtropical evergreen broad-leaved forest dominated by Quercus/Lithocarpus and Castanopsis at middle altitudes of mountains around the basin, and (iii) evergreen coniferous forest of Abies, Picea and other genera at the higher elevations of the mountains. Based on the habits of the NLRs, the prevailing climate was probably humid subtropical and thus differed from the present-day hot and dry climate supporting savanna. It is suggested that subtropical forest was predominant in Yunnan, while tropical rainforest occurred in southwest Asia and India during the same period. The uplift of the mountains near the Qinghai-Tibet plateau in western Yunnan presumably acted as a barrier to block warm and humid air from the Indian Ocean, which influenced the dispersal and distribution of plants.

Cristina I. Nunes, Roberto R. Pujana, Ignacio H. Escapa, María A. Gandolfo and N. Rubén Cúneo

Edited by E. A. Wheeler

ABSTRACT

An angiospermous wood from the Lower Cretaceous (upper Albian) of the Cerro Barcino Formation, Chubut Group, central Patagonia, Argentina, is described. Its estimated minimum diameter is 40 cm and it is significant as the oldest known angiosperm wood for South America.

It has indistinct growth ring boundaries, vessels solitary and in radial multiples, simple perforation plates, alternate intervessel pits, vessel-ray parenchyma pits oval to horizontally elongated, heterocellular rays, non-septate fibres, axial parenchyma absent, and abundant tyloses. Because this Albian wood has non-septate fibres we assign it to Carlquistoxylon, even though it has a general combination of characters similar to that of Paraphyllanthoxylon, which has septate fibres. The number of vessels per radial multiple, vessel tangential diameter and frequency, vessel-ray parenchyma pitting, and absence of axial parenchyma distinguish the fossil described here from the only previously known species of Carlquistoxylon: Carlquistoxylon nacimientense; therefore, a new species is erected. Because of the close similarities between this new specimen and Paraphyllanthoxylon species, comparisons with all the species included in both genera are provided. Systematic affinities for this wood are discussed considering previous discussions for both Paraphyllanthoxylon and Carlquistoxylon affinities. As the oldest described angiosperm wood in South America to date, this specimen provides critical information on the diversity and growth habit of Cretaceous angiosperms from the Southern Hemisphere.

Gayatri Mishra, David A. Collings and Clemens M. Altaner

Edited by Uwe Schmitt

ABSTRACT

Eucalyptus bosistoana F. Muell. is valued for its naturally durable heartwood. As part of an E. bosistoana breeding programme, we have tested the hypothesis that there is a prolonged transition from sapwood to heartwood in young trees, resulting in a wide transition zone. This needs to be considered when assessing trees for heartwood quantity and quality. Heartwood formation was investigated in radial profiles in cores from bark to bark of 6-year-old trees with conventional and confocal microscopy, and with a range of different staining techniques that visualised the physiological changes taking place in the parenchyma cells. Using immunolabelling with antibodies against histone proteins and α-tubulin, histochemical staining using potassium iodide (I3-KI) and fluorescence emission spectral scanning, we demonstrated that in heartwood nuclei, microtubules, reserve materials (starch) and vacuoles were absent. The observations revealed that 6-year-old E. bosistoana trees contained heartwood. The loss of water conductivity by tyloses formation and the death of the parenchyma cells occurred in close proximity resulting in a transition zone of ~1 cm.

Antonio C. F. Barbosa, Gisele R. O. Costa, Veronica Angyalossy, Tássia C. Dos Santos and Marcelo R. Pace

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.

Cláudia Fontana, Gonzalo Pérez-de-Lis, Luiz Santini-Junior, Paulo César Botosso, Cristina Nabais, Mario Tomazello-Filho and José Luís Penetra Cerveira Lousada

ABSTRACT

The wood anatomy of Copaifera lucens Dwyer was studied with an emphasis on its growth ring boundaries. Growth rings are visible to the naked eye and demarcated by marginal parenchyma bands and, sometimes, by thick-walled fibers in the latewood. Secretory canals are associated with marginal parenchyma bands, but not all marginal parenchyma bands are associated with canals. Paratracheal parenchyma is vasicentric to lozenge-aliform. Rays are 1–4-seriate, heterocellular and non-storied. Vessels are visible to the naked eye, diffuse, predominantly solitary, some in multiples, sometimes filled with gums. Crystals present. Wood anatomical characteristics of C. lucens are in agreement with those previously reported for other species of Copaifera. In addition to what had already been described for C. lucens, we observed gelatinous fibers, and some bifurcate fibers, and extremely rare clustered vessels. The growth ring boundaries are well-defined in mature wood but less distinctive near the pith. There are also partial and confluent (wedging) rings, which are difficult to classify by anatomy only, but which represent false rings and complicate tree-ring analysis in this species.

Alexei A. Oskolski, Anna V. Stepanova, Luliang Huang and Jianhua Jin

Edited by E.A. Wheeler

ABSTRACT

The taxonomic position of fossil woods suggested to be related to Bischofia is reassessed based on the examination of the wood anatomy of recently collected samples of its two modern species (B. javanica and B. polycarpa). Woods of B. palaeojavanica from the middle Pliocene of India, and B. javanoxyla from the early Miocene of northern Taiwan have features of extant B. javanica. In contrast, the Eocene Bischofia maomingensis (South China) differs from Bischofia in a number of features and we propose a new combination Chadronoxylon maomingensis (Feng et Jin) Oskolski, Stepanova, Huang et Jin. Bischofia palaeojavanica from the latest Cretaceous–earliest Paleocene Deccan Intertrappean Beds, India, and all other pre-Miocene woods assigned to Bischofia differ from extant Bischofia in vessel diameters, vessel element lengths, intervessel pit sizes, position of vessel-ray pits, and/or abundance of sheath cells in rays. Therefore, their generic position must be reconsidered, and there is no reliable record of Bischofia wood older than Miocene.

João Carlos Ferreira de Melo Júnior and Maria Regina Torres Boeger

ATLAS OF VESSEL ELEMENTS

Identification of Asian Timbers

Stephanie Helmling, Andrea Olbrich, Immo Heinz and Gerald Koch

Tatiana V. Tarelkina, Ludmila L. Novitskaya and Nadezhda N. Nikolaeva

Associate-editor Veronica De Micco

ABSTRACT

This study is a continuation of research on the role of sucrose in figured wood formation in temperate trees. Different concentrations of sucrose solutions were administered for 7 weeks to trunk tissues of Betula pendula Roth, Alnus incana (L.) Moench and Populus tremula L. Then xylem anatomy was examined with particular emphasis to the number of vessels and the spatial orientation of xylem elements. In B. pendula and A. incana a high level of exogenous sucrose caused a reduction in the number and size of xylem vessels, even to the point of absence of vessels. Sucrose concentrations of 100 and 200 g l-1 induced the formation of curly grain and anomalous club-shaped rays in xylem of B. pendula. Populus tremula xylem was not significantly altered by the experiment; the xylem anatomy was more seriously affected by wounding than by sucrose. In B. pendula and A. incana the wood formed during the experiment was similar to figured wood of these species. The decrease in the number and size of vessels in the xylem formed during the experiment possibly suggests that high concentrations of sucrose lead to a decline in the level of physiologically active auxin. Changes in the orientation of xylem elements points to a disruption of basipetal auxin transport. Further biochemical and physiological studies are needed to provide more comprehensive understanding of the relationship between sucrose and auxin during the development of figure in wood.

Vladimír Račko, Ol’ga Mišíková, Jaroslava Štefková and Igor Čunderlík

ABSTRACT

Biologically degraded wood in advanced stages of decay has a very soft and brittle structure that causes many problems during sectioning. Embedding wood specimens in different kinds of media ensures preparation of good quality microsections, but the preparation time is very long. The proposed method does not only have a reduced preparation time but also minimizes costs and consumption of chemicals while improving stabilization of the specimen and enhancing the quality of sections. The crux of the method is application of a reinforcing layer of transparent nail polish gel on a dry specimen that has been only stabilized (not embedded) with PEG 1500 medium. The gel is applied on a specimen in two layers just before sectioning. The first layer infiltrates the specimen sufficiently deep to fill the lumens and cell walls and allows preparation of thin sections from decayed wood. The second layer reinforces the section and allows better handling. Subsequently, the reinforcing and embedding layers are removed using pure acetone. This innovative method has so far been successfully tested on specimens that were degraded by the fungus Pleurotus ostreatus (mass loss 55% and 83%) and the fungus Phaeolus schweinitzii (mass loss 45%), taken from Fagus sylvatica and Pinus sylvestris species, a hardwood and softwood respectively with contrasting wide vessels and narrow tracheids.

Anna B. Wilczek, Muhammad Iqbal, Wieslaw Wloch and Marcin Klisz

ABSTRACT

All cell types of the secondary xylem arise from the meristematic cells (initials) of the vascular cambium and grow under mechanical constraints emerging from the circular-symmetrical geometry that characterises many tree trunks. The course of intrusive growth of cambial initials has been elucidated, but is yet to be described in the case of xylem fibres. This study explains the geometry of intrusive growth of the secondary xylem fibres in the trunk of Robinia pseudoacacia. Long series of serial semi-thin sections of the vascular cambium and the differentiating secondary xylem were analysed. Since fibres grow in close vicinity to expanding cells of the derivatives of the vascular cambium, we assumed that they have similar growth conditions. Dealing with the cylindrical tissue of the vascular cambium in a previous study, we used a circularly symmetrical equation for describing the growth mechanism of cambial initials. Like the cambial initials, some of the cambial derivatives differentiating into the various cell types composing the secondary xylem also exhibit intrusive growth between the tangential walls of adjacent cells. As seen in cross sections of the cambium, intrusively growing initials form slanted walls by a gradual transformation of tangential (periclinal) walls into radial (anticlinal) walls. Similarly, the intrusive growth of xylem fibres manifests initially as slants, which are formed due to axial growth of the growing cell tips along the tangential walls of adjacent cells. During this process, the tangential walls of adjacent cells are partly separated and dislocated from the tangential plane. The final shape of xylem fibres, or that of vessel elements and axial parenchyma cells, depends upon the ratio of their intrusive versus symplastic growths in the axial, circumferential and radial directions.

Ekaterina L. Kotina, Patricia M. Tilney, Abraham E. van Wyk, Alexei A. Oskolski and Ben-Erik van Wyk

ABSTRACT

A remarkable, almost fur-like “indumentum” of velvety “hairs” (sometimes referred to as “fungi”) occurs on the roots (and to a lesser extent also on the trunk) of Lannea schweinfurthii var. stuhlmannii and is known as vhulivhadza in the Venda language (Tshivenḓa). The hairs are traditionally used by the Venda people (Vhavenḓa) of the Limpopo Province of South Africa, for various biocultural purposes. A detailed anatomical study of the origin, structure and development of these unusual “hairs” showed that they are of peridermal origin and develop from dense clusters of phelloid cells which are scattered within the stratified phellem. These cells are capable of considerable radial elongation thus forming hair-like radial files of elongated phelloid cells. The “hairy” patches on the bark may also develop from lenticels which become hypertrophied. These clusters of phelloid cells resemble the hyperhydric tissue which is reportedly formed in periderm of stems exposed to a water-saturated environment in some plant species. The formation of hyperhydric-like tissue in roots and stems of L. schweinfurthii var. stuhlmannii occurs, however, under relatively arid conditions. Since this tissue contains large intercellular spaces, it may also be regarded as a specialized type of aerenchymatous phellem. The adaptive significance, if any, of the phelloid “hairs” remains unknown.

Rena T. Schott and Anita Roth-Nebelsick

Abstract

In this study, the ice nucleation activity (INA) and ice nucleation temperature (INT) as well as extracellular ice formation within the bark were determined for three woody species with different degrees of frost resistance, Betula nana, Betula albosinensis and Castanea sativa. Current-year stems and at least 2-year old stems of B. nana and C. sativa as well as current-year stems of B. albosinensis were compared, during summer (non-acclimated state) and winter (acclimated state), to evaluate possible ontogenetic and seasonal differences. Acclimated plant parts of the selected species revealed nearly similar results, with an INT from -7.52 to -8.43°C. The current-year stems of B. nana had a somewhat higher INT than the older stems. Microscopic analysis showed that extra-cellular ice formation occurred in the intercellular spaces within the bark of stems of B. nana, B. albosinensis and C. sativa. Size of the intercellular spaces of the bark were species-specific, and B. nana showed the largest intercellular space volume. While freezing behavior and extracellular ice formation thus followed principally the same pattern in all considered species, B. nana is obviously capable of dealing with large masses of extracellular ice which accumulate over extended periods of frost, making B. nana capable of protecting living tissue in colder regions from freezing damage.

Veronica De Micco, Enrica Zalloni, Giovanna Battipaglia, Arturo Erbaggio, Pasquale Scognamiglio, Rosanna Caputo and Chiara Cirillo

ABSTRACT

Projected changes in drought occurrence in the Mediterranean region are raising concerns about the adaptive capability of rainfed crops, such as grapevine, to increasing aridity. Cultivation management, especially the techniques influencing the hydraulic pathway, can play a role in plant adaptation to drought for the consequent changes in wood anatomical functional traits. The aim of this study was to assess the effect of grafting on wood anatomy in tree-ring series of Vitis vini-fera L. ‘Piedirosso’ grapevine cultivated in a volcanic area in Southern Italy. Tree-ring anatomy was analysed in vines grown on their own roots or grafted onto 420A rootstock. Results showed that grafted vines had a higher occurrence of wood traits linked with safety of water transport if compared with non-grafted vines. Grafting induced the formation of tree rings with higher incidence of latewood also characterised by narrower and more frequent vessels if compared with non-grafted vines. This study suggested a different regulation of water flow in the grafted and non-grafted vines. Such findings support the analysis of wood anatomy as a tool to drive decisions linked with plant cultivation management. In this specific case, our results encourage to further explore the change from a traditional cultivation with own-rooted grapevines towards grafted models inducing better xylem adaptation to increasing drought.

Oscar Troncoso and Alina Greslebin

ABSTRACT

Phytophthora austrocedri is a straminipilous (heterokonta) organism that causes mortality of Austrocedrus chilensis, an endemic Cupressaceae from the Patagonian Andes forest in temperate South America. This soil pathogen colonizes and kills the roots and extends up to the stem causing necrosis of cambium, phloem and xylem ray parenchyma. An anatomical study of affected tissues was conducted in order to better understand the process of pathogen colonization and tree response. It was found that tracheids of the xylem of affected trees showed large numbers of trabeculae, both rod- and plate-shaped. The occurrence of these structures was clearly associated with the necrotic lesion area, since the trabeculae were rare in healthy tissues above the necrotic lesion. Trabeculae occurred in a variety of arrangements: solitary or in long files, single, double or triple. Our results could indicate that trabeculae proliferation in tracheids of A. chilensis trees is induced by the stress generated by the P. austrocedri invasion. Whether this is triggered by a nonspecific stress response or in direct response to the pathogen remains to be tested.

Alexa Höhn and Katharina Neumann

Identification of archaeological or soil charcoal in a species-rich biome, such as the Central African rainforest, is challenging because of the large number of woody taxa with similar and overlapping wood anatomical features. Valid environmental or archaeological interpretations can only derive from reliable and transparent identifications that allow comparison of and referencing between different charcoal assemblages. The identification of 30 archaeological charcoal types from the site Dibamba in southern Cameroon serves as a starting point for a discussion on classification and naming. These 30 types are fully documented and illustrated in the Supplementary Online Material (SOM). The discussion underlines the basics of “good practice” of charcoal identification in a speciesrich tropical environment. The value of differential diagnosis is stressed, as is the importance of leaving identification levels on higher taxonomic level if necessary. We argue that the level of identification must be reflected in the name of the charcoal type. Names of charcoal types are written in small capitals to clearly distinguish them from botanical taxa with which they are not necessarily identical. The Dibamba charcoal assemblage offers the first and so far unique possibility to directly comprehend human impact on the structure and composition of West Central African rainforest over the last 3000 years. The paleoenvironmental significance of the results presented here will be subject of a forthcoming publication.

Luciana Witovisk, Ruy J.V. Alves, Alessandra R. Guimarães and Nilber G. da Silva

The first reports of a dead forest on Trindade Island are from the 18th century. Since then, the tentative identifications of the trees with red wood included Caesalpinia, Acacia, Rapanea, Pisonia, Eugenia and Colubrina, the latter having been confirmed by three independent wood anatomists familiar with Brazilian woods. In the 1960s Johann Becker was the last to sample a live Colubrina glandulosa Perkins var. reitzii on Trindade, which was presumed to be a remnant of the extinct forest. Based on this information, along with the eradication of feral goats from the island in 2005, thousands of C. glandulosa seedlings were reintroduced to Trindade. These trees, which grew well at first, are now collectively dying, less than two decades after planting. Their wood colour is much lighter than that of the dead trees, raising doubts about the latter’s correct identification. Herein we report the first detailed descriptions of two wood types from the extinct forest of Trindade, confirming the presence of C. glandulosa and reporting the presence of Paratecoma peroba (Bignoniaceae), a novel occurrence for the island. Radiocarbon dating of a dead C. glandulosa tree confirms that it belongs to the forest which died three centuries ago. The preserved wood proves that the extinct forest was not monospecific and suggests that further sampling of the remaining dead wood may enhance the floristic knowledge of the forest which once covered most of the island with additional species.

Ye-Ming Cheng, Xiao-Nan Yang, Zhe-Feng He, Bing Mao and Ya-Fang Yin

We describe a new species, Gleditsioxylon jiangsuensis (Leguminosae), a new record of Robinia zirkelii (Platen) Matten, Gastaldo & Lee (Leguminosae), and a new record of Moroxylon xinhuaensis Yin, Liu & Cheng (Moraceae) from the early Miocene strata of Sihong County in Jiangsu Province, eastern China. Gleditsioxylon jiangsuensis sp. nov. is the first report of Gleditsioxylon fossil wood from China. These fossil woods, combined with paleontological records, may indicate that the boundary between the subtropical and the temperate zones in eastern China during the early Miocene was located north of its modern location.

Yuzou Sano, Hisashi Abe, Ryo Funada, Keiji Takabe and Pieter Baas

Ahmad Alkadri, Capucine Carlier, Imam Wahyudi, Joseph Gril, Patrick Langbour and Iris Brémaud

Sycamore maple (Acer pseudoplatanus L.) is a wood species particularly known for its wavy grain figure and its high-value utilization among luthiers and craftsmen for making musical instruments or furniture. In this study, the anatomical and physical-acoustical characteristics of its wood, taken from different trees with various surface figures, were characterized. Vibrational mechanical measurements were conducted taking into account radial and longitudinal directions and local variations. Waviness parameters were quantified on split blocks, and anatomical properties such as microfibril angle and ray dimensions were measured using light microscopy. Results provide a complete dataset on the properties of sycamore maple along a gradient of the wavy figure. Through statistical analysis, significant correlations were found between the measured parameters, particularly between the waviness and microfibril angle, and between the anatomical features and the specific modulus of elasticity and damping by internal friction of the wood in the longitudinal direction. Anisotropy was found to be very low but was not satisfactorily explained by the studied anatomical features. Prospects for future studies on the wavy figure are discussed.

Adya P. Singh, Andrew H.H. Wong, Yoon Soo Kim and Seung Gon Wi

Naturally durable heartwoods, where available, continue to be used as support structures in environments considered hazardous, particularly in ground contact. However, durability of heartwoods against wood decay microorganisms varies. Therefore, it is important to evaluate heartwood products for their in-service performance in order to maximise benefits derived from this valuable natural resource of limited supply. In the work presented, wood pieces from a kempas (Koompassia malaccensis) utility pole that had been placed in service in an acidic soil in Malaysia, and in time had softened at the ground-line position, were examined by light and transmission electron microscopy to evaluate the cause of deterioration.

Light microscopy (LM) provided evidence of extensive attack on fibre cell walls by cavity-producing soft rot fungi. Transmission electron microscopy (TEM) revealed in greater detail the distribution and micromorphologies of cavities as well as their relationships to the fine structure of fibre cell walls, which consisted of a highly electron dense middle lamella, a moderately dense S1 layer and a multilamellar S2 layer with variable densities, reflecting differences in lignin concentration. The resistance of the moderately dense S1 layer to soft rot was a feature of particular interest and is the main focus of the work presented. The resistance appeared to be correlated with high lignification of the outermost region of the S2 wall, interfacing with the S1 layer, an unusual cell wall feature not previously described for normal wood.

Nadia S. Santini, James Cleverly, Rolf Faux, Katie McBean, Rachael Nolan and Derek Eamus

Xylem traits such as xylem vessel size can influence the efficiency and safety of water transport and thus plant growth and survival. Root xylem traits are much less frequently examined than those of branches despite such studies being critical to our understanding of plant hydraulics. In this study, we investigated primary lateral and sinker roots of six co-occurring species of semi-arid Australia. Two species are restricted to a floodplain, two were sampled only from the adjacent sand plain, and two species co-occur in both habitats. We assessed root wood density, xylem traits (i.e., vessel diameter, fibre and vessel wall thickness), outer pit aperture diameter and calculated theoretical hydraulic conductivity and vessel implosion resistance. We hypothesized that (1) roots have larger xylem vessel diameters and lower wood density than branches of the same species and that (2) there is an inverse correlation between theoretical sapwood hydraulic conductivity and vessel implosion resistance for roots. Variation in root wood density was explained by variations in xylem vessel lumen area across the different species (r2 = 0.73, p = 0.03), as hypothesized. We rejected our second hypothesis, finding instead that the relationship between theoretical hydraulic conductivity and vessel implosion resistance was not maintained in roots of all of our studied species, in contrast to our previous study of branches from the same species. Xylem traits were found to depend upon habitat and eco-hydrological niche, with the groupings including (i) arid-adapted shrubs and trees with shallow lateral roots (Acacia aneura and Psydrax latifolia), (ii) trees restricted to the floodplain habitat, both evergreen (Eucalyptus camaldulensis) and deciduous (Erythrina vespertilio) and (iii) evergreen trees co-occurring in both floodplain and adjacent sand plain habitats (Corymbia opaca and Hakea sp.).

Bei Luo, Yeling Ou, Biao Pan, Jian Qiu and Takao Itoh

The structure and development of interxylary phloem (IP) and external phloem in Aquilaria sinensis were investigated using light and scanning electron microscopy. Complete IP strands were isolated, measuring 14 ± 4 mm in length and 417 ± 124 μm in width. The outer margin of IP was composed of two to three layers of fusiform parenchyma cells. The development of IP can be divided into five stages: 1) Locally IP starts its differentiation within a small segment of a broad cambial zone, at the cost of xylem differentiation. 2) Inward growth of IP advances, and fibres and sieve tubes differentiate. 3) IP is constricted by the encroachment of immature xylem cells between cambium and immature IP. 4) IP is isolated from the cambium and surrounded by immature, non-lignified xylem tissue. 5) IP is surrounded by lignified xylem tissue, and the fibres within IP become lignified.

In all the phloem islands in a ten-year-old stem, sieve elements showed positive staining of callose with aniline blue. However, no staining of callose was observed in the external secondary phloem of agarwood trees collected from two different sites. No sieve tubes or sieve pores were detected by SEM observation of numerous serial cross and radial sections of the external phloem. We therefore conclude that sieve tubes are absent from the external phloem or extremely rare and that the transport of photosynthetic products in the stem of A. sinensis takes place in the interxylary phloem.

Hiromi Shibui and Yuzou Sano

Betula species have phellems with distinctive features such as stratification into thin paper-like layers, which are easily split in the tangential direction, and linear lenticels. We aimed to clarify the structure and development of the characteristic phellems of B. maximowicziana. In a normal periderm, phellem, phellogen, and phelloderm consist of tangentially elongated cells that are arranged in radial files. The phellem consists of layers of 1.4 ± 0.5 cells thick of very thin-walled phellem cells alternating with layers of 7.1 ± 1.5 thick-walled phellem cells. Seasonal sampling showed that the former and the latter were formed in the early and middle-to-late stages of the growing period, respectively. In lenticels, filling tissues alternated with closing layers. Most cells were collapsed and loosely packed in the filling tissue while all cells were intact and arranged in radial files in the closing layers. The filling tissue cells had unique walls that appeared to be easily deformed. Each annual increment of phellem in Betula is composed of a thin-walled cell layer (early phellem) and a thicker layer of thick-walled cells (late phellem). It is likely that the combination of filling tissue and closing layer in lenticels helps to perform the dual functions of gas exchange and protection, and that the collapse of the cells in filling tissue effectively contributes to gas permeability.

Ünal Akkemik, Nevriye Neslihan Acarca and Murat Hatipoglu

ABSTRACT

Silicified wood preserved in the Güdül fossil forest site in the Galatian Volcanic Province (GVP) near Ankara in Central Anatolia is described. The material comprises six petrified wood samples that date from early to middle Miocene. The woods have very low rays (2–5 cells high), bordered tracheidal pitting (9–10 μm), pinoid cross-field pits and very thin, unpitted, smooth walls of axial parenchyma and rays. This combination of characters indicates affinity to the fossil-genus Glyptostroboxylon. The presence of this wood genus suggests that the local environment was either riparian or wetland forest.

Peter Gasson, Paula Rudall, David Cutler, Barry Tomlinson, Elisabeth Wheeler and Pieter Baas

Diana K. Pérez-Lara, Carlos Castañeda-Posadas and Emilio Estrada-Ruiz

ABSTRACT

We describe a new fossil wood from the El Bosque Formation (Eocene) in Chiapas, southern Mexico. It has a combination of features found in the Anacardiaceae, including distinct growth rings, diffuse porosity, vessels solitary and in radial multiples of 2–3, simple perforation plates, medium to large alternate intervessel pits, vessel-ray parenchyma pits rounded and elongate with reduced borders, septate and non-septate fibers, axial parenchyma scanty paratracheal, vasicentric, apotracheal diffuse, Kribs heterogeneous rays type IIA, and multiseriate rays with radial canals. The mosaic of features of this wood supports the erection of a new genus, Bosquesoxylon Pérez-Lara, Castañeda-Posadas et Estrada-Ruiz. This new genus of anacardiaceous fossil wood extends our knowledge of this family’s history and offers hints on the possible relationships with floras from other localities worldwide, especially North America and Asia.

Anumeha Shukla and R.C. Mehrotra

ABSTRACT

The systematics of a fossil wood assigned to Duabangoxylon (family Lythraceae) is described from the Deccan Intertrappean beds of Kutch, Gujarat, western India considered to be late Maastrichtian to early Danian in age. This fossil is the oldest record of Duabanga as its previous records are not older than Eocene. As the intertrappean flora of Kutch is poorly known, the present fossil not only enriches this flora but also helps in the reconstruction of palaeoclimate.

Oris Rodriguez-Reyes, Peter Gasson, Carolyn Thornton, Howard J. Falcon-Lang and Nathan A. Jud

ABSTRACT

We report fossil wood specimens from two Miocene sites in Panama, Central America: Hodges Hill (Cucaracha Formation; Burdigalian, c. 19 Ma) and Lago Alajuela (Alajuela Formation; Tortonian, c. 10 Ma), where material is preserved as calcic and silicic permineralizations, respectively. The fossils show an unusual combination of features: diffuse porous vessel arrangement, simple perforation plates, alternate intervessel pitting, vessel–ray parenchyma pits either with much reduced borders or similar to the intervessel pits, abundant sclerotic tyloses, rays markedly heterocellular with long uniseriate tails, and rare to absent axial parenchyma. This combination of features allows assignment of the fossils to Malpighiales, and we note similarities with four predominantly tropical families: Salicaceae, Achariaceae, and especially, Phyllanthaceae, and Euphorbiaceae. These findings improve our knowledge of Miocene neotropical diversity and highlight the importance of Malpighiales in the forests of Panama prior to the collision of the Americas.

Short communication

Periderm tubes: an addition to the List of microscopic bark features

Simcha Lev-Yadun

Elisabeth A. Wheeler, Rashmi Srivastava, Steven R. Manchester and Pieter Baas

Associate-editor Michael Wiemann

ABSTRACT

Background and approach – The Deccan Intertrappean Beds of Central India contain a diverse assemblage of fossil plants, including petrified woods from 15 localities. These beds are dated at c. 67–64 Ma, i.e. latest Cretaceous–earliest Paleocene and span the K-Pg boundary, a significant time in angiosperm history. At this time, the Indian tectonic plate was halfway on its journey from Gondwana to its collision with Asia, and relatively close to the equator. We provide descriptions in IAWA Hardwood List codes for 47 species of Deccan fossil woods, based on our examination of thin sections of these woods, mostly holotypes that are housed at the Birbal Sahni Institute of Palaeobotany, Lucknow, India. An appendix lists all validly published Deccan wood species of which we are aware, including 52 that we were not able to examine.

Main results – The Deccan fossil woods described herein include the oldest known occurrences of some orders, families or genera viz. Lamiales (Lamia-ceae), Achariaceae (Hydnocarpus-like wood), Anacardiaceae, Simaroubaceae (Ailanthus-like and Simarouba-like woods), subfamily Leeoideae (Vitaceae), subfamily Myrtoideae (Myrtaceae), subfamily Planchoideae (Lecythidaceae), tribe Castilleae (Moraceae), tribes Grewioideae and Sterculioideae (Malvaceae). These first fossil records are discussed with reference to other macrofossil and pollen records of the same or related clades. They complement recent work on the oldest known Olea and Connaraceae also documented by Deccan woods.

For the Deccan woods we examined, we could confirm the earlier taxonomic assignment at least down to order or family level for 29 taxa. Ordinal level affinities are ambiguous for eight of the taxa. In two cases, we revised the taxonomic assignment to other families; for another eight, the original assignment was found to be incorrect, but we are unable to suggest alternative affinities.

Evolutionary implications – Only 3% of all Deccan woods have scalariform perforations and the incidences of so-called specialized features in the Baileyan sense are high, so these woods have a remarkably “modern” aspect. This is anomalous in comparison with contemporaneous fossil woods from higher paleolatitudes, and seemingly they are more “derived” than the recent flora. In these respects, the Deccan woods constitute a unique assemblage. The low incidence of scalariform perforations suggests xeric conditions, while – in contrast – the low incidence of distinct growth ring boundaries suggests an aseasonal everwet climate. It is speculated that convergent xylem specialization, especially the selection for simple perforations, was enhanced by the climatic conditions found at low paleolatitudes with high temperatures as would characterize the Deccan Intertrappean Beds at the K-Pg boundary.

Nathan A. Jud and Jeremy I. Dunham

Silicified woods from near the town of Ocú on the Azuero Peninsula, Panama were first reported by Stern and Eyde in 1963; however, the significance of these fossils has been largely overlooked. Well-characterized fossil floras from Central America can be used to test hypotheses related to the historical biogeography and paleoclimate of the Neotropics. We describe 10 new wood types and one palm based on 22 samples from Oligo-Miocene deposits. Affinities at the family/order level include Fabaceae, Lauraceae, Moraceae, Sapotaceae, Euphorbiaceae, Arecaceae, Sapindales, Ericales, and Humiriaceae. The fossil woods are fragmentary and have not been found in-place, but the size and angularity of the specimens suggests minimal transport from the site of growth. We compared these woods with calcareous woods from the Lower Miocene Cucaracha Formation and silicified woods from the upper Miocene Alajuela Formation using Rare Earth Element (REE) analysis to test the hypothesis that the Ocú woods were preserved under uniform conditions and not reworked. Although the results were ambiguous with respect to the original hypothesis, we note that the REE concentrations in silicified woods are much lower than in calcareous woods. We used comparative analysis of wood anatomical features to draw conclusions about the paleoclimate from the fossil flora. All the dicot woods are diffuse porous and none have distinct growth rings; some have very wide vessels at low frequencies. These features are typical of canopy trees in tropical lowland forests. Nonmetric multidimensional scaling of wood anatomical characters from a variety of communities and ecological categories showed that the anatomy of the Ocú woods is most similar to that found in tropical rainforests. Based on the combination of taxonomic identity and functional anatomy, we interpret these fossils as evidence for humid to perhumid megathermal climate in Panama during the late Paleogene-early Neogene.

Marco Fioravanti, Giuseppina Di Giulio, Giovanni Signorini, Gabriele Rossi Rognoni, Nicola Sodini, Giuliana Tromba and Franco Zanini

We identified the wood of the sticks of eight bows in the historical collection of musical instruments in the Galleria dell’ Accademia in Florence. Wood identification was carried out non-invasively (i.e., without sampling wood from the original objects), because the removal of samples from fine musical instruments will affect their aesthetic integrity and/or functional quality. Identification attempts using reflected light microscopy of wood surfaces, gave only partial results due to the poor quality of the surfaces and the particular geometry of the sticks that does not have any transverse surface. Application of Synchrotron light X-ray microtomography (µCT) in phase-contrast mode to the whole sticks allowed us to obtain stacks of transverse-sectional images that, processed as virtual volumes, revealed several anatomical features. With µCT it was possible to identify three bows as Brosimum guianense (Moraceae), one bow as Caesalpinia echinata (Caesalpiniaceae), and four bows as Manilkara sp. (Sapotaceae).

D.W. Woodcock, H.W. Meyer and Y. Prado

The fossil woods and leaves of the Fossil Forest Piedra Chamana represent a diverse assemblage of plants dating to 39 Ma (late Middle Eocene). The fossils are preserved in an ashfall and overlying lahar deposits near the small village of Sexi in the northern Peruvian Andes (central Cajamarca). The assemblage includes dicot wood types and leaf morphotypes, as well as a diversity of monocot material. The ~30 dicot wood types are referred to the families Acanthaceae, Anacardiaceae, Apocynaceae, Combretaceae, Cordiaceae, Dipterocarpaceae, Euphorbiaceae, Fabaceae, Lechythidaceae, Lythraceae, Malvaceae, Melastomataceae, Muntingiaceae, Rubiaceae, Rutaceae, and Sapindaceae. Described herein are descriptions of the first 17 wood types that have been assigned to the families Acanthaceae through Lythraceae; descriptions of the additional wood types will appear in a later paper. The paleovegetation can be characterized as lowland tropical forest with a dry aspect based on preliminary analysis of floristic affinities and wood anatomical characteristics of the fossils.

Neda Lotfiomran and Michael Köhl

Reliable information on tree growth is a prerequisite for sustainable forest management (SFM). However, in tropical forests its implementation is often hampered by insufficient knowledge of the growth dynamics of trees. Although tree ring analysis of tropical trees has a long history, its application for SFM has only recently been considered. In the current study, we illustrate both the potentials and limitations of a retrospective growth assessment by tree ring analysis under the prevailing tropical conditions in a Surinamese rain forest. For this purpose, 38 commercial tree species were screened and grouped into three categories according to the visibility of their tree ring boundaries: (I) tree rings absent or indistinct, (II) distinct but partially vague tree rings which enable approximate age estimation, (III) very distinct tree rings. In 22 out of 38 commercial tree species distinct to very distinct tree ring boundaries could be identified. The anatomy of tree ring boundaries was described following Worbes and Fichtler (2010). Four species with distinct growth rings, Cedrela odorata, Hymenaea courbaril, Pithecellobium corymbosum and Goupia glabra, were studied in greater detail. Time-series analysis was used to characterise their radial growth. From the tree ring width, the annual diameter increment and cumulative diameter growth were calculated to find long-term growth patterns. Pithecellobium corymbosum and partially Hymenaea courbaril followed a typical S-shaped growth curve. By contrast, Goupia glabra and Cedrela odorata did not exhibit an age-related decrease of growth, but showed a constant linear growth over their entire life span. If based on more sample trees, such data can provide target-oriented information for improving SFM in tropical forests.

Caian Souza Gerolamo and Veronica Angyalossy

This work compares potential xylem hydraulic efficiency among Bignoniaceae lianas, shrubs and trees. Five species from each growth habit were analysed to determine variance among habits based on quantitative and qualitative wood anatomical features. Potential hydraulic conductivity was calculated for each species in order to compare efficiency of water transport. Cambial variants are present in the Bignonieae tribe, as phloem wedges in lianas and phloem arcs in shrubs. Lianas present vessel dimorphism, quantitatively evidenced by the ratio of maximum by minimum vessel diameter of about 20, higher percentage of vessel area and lower percentage of fibres compared with the self-supporting species studied here. Potential hydraulic conductivity is higher in lianas due to the presence of wider vessels and it is hypothesised that the narrow vessels can function as back-up for water conduction when wider vessels are cavitated.

Arabic Type-Making in the Machine Age

The Influence of Technology on the Form of Arabic Type, 1908–1993

Series:

Titus Nemeth

Arabic is the third most widely used script in the world, and gave rise to one of the richest manuscript cultures of mankind. Its representation in type has engaged printers, engineers, businesses and designers since the 16th century, and today most digital devices render Arabic type. Yet the evolution of the printed form of Arabic, and its development from metal to pixels, has not been charted before. Arabic Type-Making in the Machine Age provides the first comprehensive account of this history using previously undocumented archival sources. In this richly illustrated volume, Titus Nemeth narrates the evolution of Arabic type under the influence of changing technologies from the perspective of a practitioner, combining historical research with applied design considerations.

Nathan A. Jud, Elisabeth A. Wheeler, Gar W. Rothwell and Ruth A. Stockey

Fossil angiosperm wood was collected from shallow marine deposits in the Upper Cretaceous (Coniacian) Comox Formation on Vancouver Island, British Columbia, Canada. The largest specimen is a log at least 2 m long and 38 cm in diameter. Thin sections from a sample of this log reveal diffuseporous wood with indistinct growth rings and anatomy similar to Paraphyllanthoxylon. Occasional idioblasts with dark contents in the rays distinguish this wood from previously known Paraphyllanthoxylon species and suggest affinity with Lauraceae. The log also includes galleries filled with dry-wood termite coprolites. This trunk reveals the presence of tree-sized angiosperms in what is now British Columbia, and the association of dry-wood termites with angiosperm woods by the Coniacian (89 Ma). To understand the significance of this discovery, we reviewed the record of Cretaceous woods from North America. Our analysis of the distribution of fossil wood occurrences from Cretaceous deposits supports the conclusion that there was a strong latitudinal gradient in both the size and distribution of angiosperm trees during the Late Cretaceous, with no reports of Cretaceous angiosperm trees north of 50°N paleo-latitude in North America. The rarity of angiosperm wood in the Cretaceous has long been used to support the idea that flowering plants were generally of low-stature for much of the Cretaceous; however, large-stature trees with Paraphyllanthoxylon-like wood anatomy were widespread at lower–middle paleo-latitudes at least in North America during the Late Cretaceous. Thus, the presence of a large Paraphyllanthoxylon log in the Comox Formation suggests that Vancouver Island has moved significantly northward since the Coniacian as indicated by other geological and paleobotanical studies.

Jimmy Thomas and David A. Collings

We describe a novel, semi-automatic method for the detection, visualisation and quantification of axially oriented resin canals in transverse sections of Pinus radiata D. Don (radiata pine) trees. Sections were imaged with a flatbed scanner using circularly polarised transmitted light, with the resin canals that contained only primary cell walls appearing dark against a bright background of highly-birefringent tracheids. These images were analysed using ImageJ software and allowed for a non-biased, automated detection of resin canals and their spatial distribution across the entire stem. We analysed 8-month-old trees that had been subjected to tilting to induce compression wood and rocking to simulate the effects of wind. These experiments showed that both rocking and tilting promoted the formation of wood and confirmed that resin canals were most common adjacent to the pith. Both the rocking and tilting treatments caused a decrease in the number of resin canals per unit area when compared to vertical controls, but this change was due to the increased formation of wood by these treatments. In tilted samples, however, analysis of resin canal distribution showed that canals were more common on the lower sides of stems but these canals were excluded from regions that formed compression wood.

Barbara Ghislain and Bruno Clair

Tension wood, a tissue developed by angiosperm trees to actively recover their verticality, has long been defined by the presence of an unlignified cellulosic inner layer in the cell wall of fibres, called the G-layer. Although it was known that some species have no G-layer, the definition was appropriate since it enabled easy detection of tension wood zones using various staining techniques for either cellulose or lignin. For several years now, irrespective of its anatomical structure, tension wood has been defined by its high mechanical internal tensile stress. This definition enables screening of the diversity of cell walls in tension wood fibres. Recent results obtained in tropical species with tension wood with a delay in the lignification of the G-layer opened our eyes to the effective presence of large amounts of lignin in the G-layer of some species. This led us to review older literature mentioning the presence of lignin deposits in the G-layer and give them credit. Advances in the knowledge of tension wood fibres allow us to reconsider some previous classifications of the diversity in the organisation of the fibre walls of the tension wood.

Philip D. Evans, Ignacio A. Mundo, Michael C. Wiemann, Gabriela D. Chavarria, Pamela J. McClure, Doina Voin and Edgard O. Espinoza

Determining the species source of logs and planks suspected of being Araucaria araucana (Molina) K.Koch (CITES Appendix I) using traditional wood anatomy has been difficult, because its anatomical features are not diagnostic. Additionally, anatomical studies of Araucaria angustifolia (Bertol.) Kuntze, Araucaria heterophylla (Salisb.) Franco, Agathis australis (D.Don) Lindl., and Wollemia nobilis W.G.Jones, K.D.Hill & J.M.Allen have reported that these taxa have similar and indistinguishable anatomical characters from A. araucana. Transnational shipments of illegal timber obscure their geographic provenance, and therefore identification using wood anatomy alone is insufficient in a criminal proceeding. In this study we examine the macroscopic appearance of selected members of the Araucariaceae and investigate whether analysis of heartwood chemotypes using Direct Analysis in Real Time (DART) Time-of-Flight Mass Spectrometry (TOFMS) is useful for making species determinations. DART TOFMS data were collected from 5 species (n =75 spectra). The spectra were analyzsed statistically using supervised and unsupervised classification algorithms. Results indicate that A. araucana can be distinguished from the look-alike taxa. Another statistical inference of the data suggests that Wollemia nobilis is more similar and within the same clade as Agathis australis. We conclude that DART TOFMS spectra can help in making species determination of the Araucariaceae even when the geographic provenance is unknown.

R.C. Mehrotra and Gaurav Srivastava

Fossil wood was collected from an in situ upright tree encased in the late Oligocene mudstone sediments exposed in the Tirap Mine, Makum Coalfield, Tinsukia district, Assam. The wood belongs to Careya of the Lecythidaceae. This genus is reported for the first time from Paleogene sediments. Its presence supports the occurrence of tropical evergreen to deciduous forests in the region during the depositional period.

Chieuda Nguyen, Ashley Andrews, Pieter Baas, Jason E. Bond, Maria Auad and Roland Dute

Chionanthus retusus and most Osmanthus spp. possess torus-bearing intervascular pit membranes in their woods. Because the genera involved are thought to be closely related and are members of the subtribe Oleinae, we hypothesized that torus morphology should be similar across taxa. A study combining light, scanning electron, and atomic force microscopy indicates that tori in both genera comprise a bipartite thickening containing a central pustular region and an encircling corona. Removal of incrusting material from the torus exposes subtending sets of parallel microfibrils. We hypothesize that the torus structures of C. retusus and Osmanthus spp. (as represented by O. armatus) have the same morphology. Optimizing torus-bearing pits on published molecular phylogenies of the subtribe Oleinae indicates parallel evolution as an explanation for torus similarity between these two groups, although a robust and well-resolved phylogeny of the Oleaceae is still lacking. A brief study of the wood anatomy of Olea dioica was also undertaken. This species is a member of the subgenus Tetrapilus and thought to be closely related to torus-bearing genera of the Oleaceae. Despite the close relationship, no tori were observed in O. dioica.

Roberto R. Pujana and Daniela P. Ruiz

A new species of Podocarpoxylon Gothan is described based on samples collected from sediments of the Río Turbio Formation. The fossil-bearing strata are lower Eocene (47–46 Mya) according to recent geochronological ages. The new species has indistinct growth ring boundaries, abundant and frequently tangentially zonate axial parenchyma, uniseriate pitting on radial walls, one half-bordered pit (= oculipore) with reduced borders and vertical aperture inclination per cross-field and medium height uniseriate rays. The new material is compared with all fossil-species of Podocarpoxylon and an inventory of all Podocarpoxylon species previously described is provided. Cross-field characters of the new species indicate affinity to the Podocarpaceae. The presence of Podocarpaceae wood augments other evidence of this family from the same stratigraphic unit.