Summary We examine the three-dimensional (3D) anatomy of normal axial (longitudinal) resin canals and fusiform rays in selected Pinus , Pseudotsuga , and Larix species, with a focus on the branching of axial resin canals and their anastomosis with radial resin canals. Helical X-ray microcomputed tomography (micro-CT) was used to acquire 3D information on specimens, which was then reconstructed using supercomputers and segmented using convolutional neural networks (CNN). We found that branching of axial resin canals can be subdivided into two main types: short branches of two or more branches separated by rays (in all species); and Y-shaped extended bifurcation separated by tracheids and subsidiary parenchyma cells (in southern pine and white pine). Anastomosis of resin canals typically occurred along the sides of axial resin canals. However, anastomosis was also observed at the termination of axial resin canals in Pinus , and in southern pine, it occasionally occurred within the axial canals. Extended axial resin canal branches could connect adjacent radial resin canals and ray parenchyma tissues tangentially. We conclude that branching of axial resin canals is common in selected Pinaceae species. The branching and anastomosis of resin canals link resin canals and their adjacent parenchyma tissues into 3D networks. The combination of X-ray micro-CT and CNN segmentation is a promising approach for evaluating the 3D structure of resin canals in softwoods and possibly analogous features in hardwoods.
Summary The Dahui Temple is a traditional wooden Buddhist structure from the Ming Dynasty, situated in Beijing, China. The pillars of the temple were constructed from hard pine ( Pinus , section Sylvestris ). Over centuries of natural weathering, the lignocellulosic polymers of the wooden pillars gradually degraded, causing changes in the microstructure and physicochemical properties of the wooden columns. Microstructural analysis showed the earlywood cells were loosely arranged and distorted, especially in the external sapwood. The latewood cell walls collapsed, losing their original morphology, and exhibited numerous micro-cracks propagating into the cell corners. Compositional analysis indicated a gradual decrease in the principal chemical components from the interior to the exterior due to natural deterioration. The outermost region, being the most severely degraded, exhibited the lowest contents of lignin (16.7%), cellulose (36.2%) and hemicellulose (12.8%). A notable decrease in the intensity of the characteristic FTIR peaks at 1735, 1370 and 1159 cm −1 was observed in the historic timber, implying partial degradation of the polysaccharide fraction, specifically hemicelluloses. Natural degradation resulted in increased relative crystallinity in the exterior regions of the historic timber. Compared to the control timber, the historic timber exhibited elevated equilibrium moisture content (EMC) values across all tested relative humidity conditions (97.3, 75.3, 57.6, 32.8%) at 25°C. Sapwood EMC was higher than heartwood EMC, with the external sapwood demonstrating the lowest dimensional stability. These findings revealed heterogeneous degradation of the historical wooden columns, providing theoretical support for the design of a long-term protective strategy.
Summary An assemblage of 65 fossil woods was recovered from deposits of the Río Guillermo Formation (Oligocene–lower Miocene). Many specimens are poorly preserved, and based on their preservation state, we propose four preservation types (A–D). Five taxonomic units were identified to genus or species level. The first, Agathoxylon antarcticum (Araucariaceae), has distinct growth rings, uni- to biseriate araucarian radial pits, araucarioid cross-fields, uniseriate rays, and absence of axial parenchyma and resin canals. The second, Nothofagoxylon scalariforme (Nothofagaceae), shows vessels solitary or in short radial multiples, simple perforation plates, predominantly opposite to scalariform intervessel pits, uniseriate rays, and diffuse axial parenchyma. The third, Nothofagoxylon cf. kraeuselii (Nothofagaceae), is poorly preserved and similar to N. scalariforme , but has predominantly biseriate rays. The fourth, also poorly preserved, identified as cf. Eucryphiaceoxylon eucryphioides (Cunoniaceae), has predominantly solitary vessels, scalariform perforation plates, scalariform intervessel and vessel-ray pits, apparent absence of axial parenchyma, and predominantly uniseriate rays. The fifth, Salicoxylon meridionale sp. nov. (Salicaceae), resembles the wood of extant Salix humboldtiana , with predominantly solitary vessels, simple perforation plates, alternate intervessel pits, simple vessel-ray pits, absence of axial parenchyma, and uniseriate heterocellular rays. Indeterminate angiosperm woods are mostly attributable to Nothofagaceae. The assemblage indicates a dominance of Nothofagaceae, consistent with the composition of the overlying/coeval Río Leona Formation and other Patagonian paleofloras; it is also consistent with the taxonomic composition of the fossil pollen and leaf assemblages of the Río Guillermo Formation. All specimens have growth ring boundaries and wood anatomical characteristics indicative of a temperate climate.
Summary The XyloTron computer vision wood identification (CVWID) system has been used to develop skilled, performant wood identification models, based on learned features that were not explicitly interpretable as traditional wood anatomical characters. One approach towards an interpretable identification system that aligns with traditional wood anatomy-based field screening would be a model that can detect growth ring boundaries (GRB). The utility of image-based GRB detection extends beyond CVWID to impactful applications in dendrochronology, quantitative wood anatomy, and allied fields. The current study expands on the work of Ravindran et al . (2026) on softwood GRB detection by training a multiscale deep supervision edge detection model on a dataset of 322 XyloTron images from 23 diffuse-porous North American hardwood species representing 19 genera. Of the 137 GRB in the 69 test images, 135 were detected (true positives) and 2 were not (false negatives). There were no false positives. Ninety-six of the 135 predicted GRB (71.1% of the total) exhibited a mean deviation of 3 pixels (approx. 9 μm) or less from their corresponding ground-truth GRB while 126 (93.3%) were within 5 pixels (approx. 16 μm) or less. This study’s diffuse-porous model substantially outperformed the Ravindran et al . (2026) softwood model in terms of false positives but underperformed slightly in terms of false negatives. Deviations between the predicted and ground-truth GRB for the diffuse-porous model were also greater than those for the softwood model, likely due to the natural lack of distinct visual cues in some GRB in the dataset.
Summary Tropical monodominant forests are rare ecosystems characterized by low diversity and high dominance of a single tree species. The role of wood anatomy in the monodominance of Brosimum rubescens in the southern Amazonia remains unknown. This is the first study to compare the secondary xylem anatomy of B. rubescens using branch wood between monodominant and mixed forests, investigating whether its anatomical traits vary across contrasting environmental conditions and contribute to a functional understanding of monodominance in the southern Amazonia. Most xylem anatomical traits of the Brosimum rubescens population did not differ significantly between monodominant and mixed forests, with broad overlap in observed values across forest types. Changes beyond these limits may compromise the species’ response to water stress. In this context, the absence of significant differences in most xylem anatomical traits between monodominant and mixed forests suggests that B. rubescens maintains similar structural characteristics across contrasting environments. This pattern indicates that its persistence and dominance may be associated with limited variation in wood anatomy, potentially complemented by adjustments in more plastic traits such as leaves, highlighting the role of xylem traits in the functional ecology of monodominant forests.
Summary The microbial degradation of waterlogged archaeological tropical hardwood (tentatively assigned to Intsia sp.) submerged in the Yellow Sea for a prolonged period was investigated using light microscopy and transmission electron microscopy. Microbial decay in tropical hardwoods, particularly under marine conditions, remains poorly understood. Anatomical analysis revealed two distinct fiber cell wall structures: (1) a structure consisting of an S 1 layer and a thick S 2 layer, in which the S 3 layer was indistinct, and (2) a multilayered structure containing one to four additional layers internal to the S 2 layer. Thin, electron-dense concentric layers were observed within these multilayered fiber walls. Both soft rot and tunneling bacterial decay were identified in all major cell types, including fibers, vessels, and axial/ray parenchyma cells, revealing heterogeneous decay patterns across these cell types. Some cells exhibited only soft rot decay, whereas others showed the co-occurrence of soft rot and tunneling bacterial decay. The concentric layers in multilayered fiber walls appeared to temporarily restrict the progression of both decay types, but were ultimately degraded. Extractives persisted in cell lumina and were particularly concentrated in simple pit membranes between parenchyma cells, which showed no evidence of microbial attack. Vestures and vestured pit membranes also demonstrated greater resistance than adjacent vessel walls, despite containing fewer extractives. These findings provide new insights into microbial degradation in waterlogged archaeological tropical hardwood under marine conditions and reveal structural features that contribute to decay resistance.
Summary Macroscopic digital images suitable for computer-vision wood identification typically present a field of view and level of anatomical detail sufficient for human-based macroscopic identification. While humans trained in wood anatomy can recognize, locate, delineate, and measure anatomical features in such macroscopic images, image-level classification algorithms cannot. Determining which pixels in an image, specifically, correspond to growth ring boundaries (GRB) could provide additional explicit quantitative data for analysis. We present a conceptual typification of twelve visual cues in digital images that delimit GRB as a step toward bridging the gap between human-defined anatomical features and the digital image characteristics representing those features. To detect GRB using these cues, we trained a multiscale deep supervision edge detection model on a dataset of 823 XyloTron images from 40 softwood species representing 9 genera and developed a simple post-processing method to convert the predicted GRB probability image to a binary mask. The model predicted all 381 GRB in the test set images, and 31 additional false-positive GRB. Once the false positives were removed, a comparison of the average differences between the ground-truth and predicted GRB showed that 73.5% were within 1 pixel while 98.2% were within 3 pixels (approx. 9.3 μm or less).
Summary Robert Hooke is widely credited with the discovery of the cell, yet in Micrographia (1665), he described dead, empty structures rather than living units. Revisiting Hooke’s original wording and reconstructing the observational steps that led to his description, we show that the term ‘cell’ emerged from the visualisation of empty compartments in dead cork tissue, made possible by specific preparation, orientation, and illumination conditions rather than by the recognition of living cellular units. This restores the term ‘cell’ to its original anatomical and observational sense.
Summary Wavy grain is a wood growth anomaly commonly found in certain tree species but absent in others. Due to its distinctive aesthetics and acoustic properties, wavy-grained wood has long been used to produce highly valued furniture and musical instruments. The underlying causes of the phenomenon of wavy grain, however, remain unclear. While evidence suggests a genetic predisposition and inheritance of the trait, the formation of wavy grain also appears to be closely linked to fundamental wood formation. This paper summarizes current knowledge on wavy grain in the form of a review and hypothesizes that its absence in some species may be related to the initiation of wood formation via cell expansion in the transition zone between juvenile and mature wood. Supporting this hypothesis is the observation that species exhibiting wavy grain tend to show markedly different wood formation dynamics compared to species in which the wavy grain does not occur.
Summary The goal of this study is to explore the hydraulic anatomy of Pacific yew ( Taxus brevifolia Nutt.) and its life history strategy implications, as the species’ small tracheids imply drought resistance, but its growth range is largely limited to temperate rainforests. Pacific yew is a conifer from the northwestern United States with unusual mechanical properties, including high xylem density with little pith-to-bark variation and relatively low xylem stiffness. These properties are informed by the species’ microstructural characteristics, with high density resulting from small tracheid diameters, and low stiffness caused by a high microfibril angle in the secondary cell wall. Tracheid dimensions are of particular interest, owing to their importance to a tree’s ability to conduct water and tolerate drought; small tracheid diameters confer resistance to drought-induced failure of the water column, but limit conductive potential. Hydraulic measurements, including hydraulic conductivity and value (the negative pressure at which 50% of a tree’s ability to conduct water is lost due to failure in the water column), were collected for several small branches. Radial SilviScan measurements of tracheid diameter and wall thickness are reported for the main stem, and for branch compression wood. Observed tracheid diameters agree with values reported in the literature, at 18–25 μm in the main stem. Branch compression wood tracheid diameters are slightly smaller at 16–19 μm. Wall thickness in the main stem ranges from 2.4 to 3 μm, while compression wood wall thickness is slightly higher at 2.8 to 3 μm. An average measured value of −5.64 MPa suggests a relatively high degree of drought tolerance in the branch xylem, and the onset of conductivity loss with increasing water stress appears gradual. Other explanations for Pacific yew’s limited growth range beyond embolism resistance are explored, including pit dimensions and stomatal control.
Summary Alnus acuminata , also known as Andean alder, is a fast-growing tree native to the Andean regions of South America. Although it is used in agroforestry systems, for soil erosion control, and in rural construction, its wood is underutilized compared to that of other planted species. This study examines the radial and between-tree variation in wood anatomical traits of A. acuminata , aiming to understand their influence on the potential use of the wood in value-added applications. Nine trees were sampled from three sites in the Cajamarca region, northern Peru, with wood cores extracted along the pith-to-bark direction. Histological analyses were conducted to assess fiber, vessel, and ray traits at four radial positions. The results showed significant radial variation in fiber length and wall thickness, and in vessel diameter, area, frequency, and percentage, with values increasing from the area near the pith toward the outer wood. Inner wood exhibited shorter and thinner fibers, while outer wood had longer and thicker fibers, enhancing mechanical stability and wood density. In contrast, the size of the rays did not vary significantly across radial positions. These patterns are crucial for distinguishing juvenile wood and mature wood, which have important implications for wood processing and the development of value-added products. The pronounced radial patterns and high between-tree variability indicate a high level of wood heterogeneity of A. acuminata trees, emphasizing the need for well-managed plantations to ensure wood quality and uniformity. This study advances the understanding of Andean alder wood properties and sets the stage for future research on its sustainable use in the Andean region.
Land-use changes are fueling the transformation of formerly grazed European landscapes. Abandoned grasslands and woodlands are undergoing rapid processes of shrub encroachment (“shrubification”), but data on the patterns and paces of these dynamics are lacking. To fill this research gap, the common hawthorn ( Crataegus monogyna ), a widely distributed thorny shrub species dominating succession in many formerly grazed woodlands, was studied. To quantify age and growth rates, dendrochronological analyses were conducted on six hawthorn populations exposed to varying climate conditions in northern Spain. To test whether growth and aboveground phenology were coupled, data on leaf phenology were obtained for two study sites and related it to radial-growth indices. Lastly, growth indices were correlated with climate (temperature, precipitation) and hydrological (river flow) variables. A positive correlation between growth indices and the leaf flush date was found in one site. Warmer spring conditions lead to earlier leaf flushing, whereas leaf fall was delayed by warm autumn conditions. Growth was enhanced by low winter and summer temperatures, and by wet winter-to-spring conditions. However, a high river flow in spring reduced growth in a floodplain forest site. In the case of hawthorn, encroachment in dry sites could be slowed down by warmer spring and summer temperatures, which constrain its radial growth, whereas wetter spring conditions could accelerate it. The pace of ongoing “shrubification” across formerly grazed regions could be modulated by aridification.
Climate change poses a significant threat to viticulture, especially in Mediterranean regions, highlighting the need for a deeper understanding of grapevine physiological responses to environmental stressors. Wood formation records environmental signals, yet it remains largely unstudied in woody horticultural crop species. This study provides the first detailed analysis of xylogenesis in Vitis vinifera L. ‘Greco’ and proposes a novel modelling approach to interpret data and identify the main environmental drivers in wood formation. Cambial activity and xylem cell production were monitored in vines cultivated in a rainfed vineyard in Southern Italy throughout the 2022 growing season. Vines were subjected to different soil management strategies: cover cropping (C), natural grassing (N) and tillage (T). A Multivariable Fractional Polynomial (MFP) model was employed to identify environmental factors associated with the different phases of xylogenesis, identified and quantified through microscopy and digital image analysis: cambial cells (CC), post-cambial enlarging cells (PC), cells in secondary wall thickening (SW) and mature cells (MT). Our results revealed a bimodal pattern of cambial activity across all treatments, with vines under tillage showing the widest final growth-ring width. The MFP model revealed that distinct environmental factors are associated with the different phases of xylogenesis. The number of CC was explained by solar radiation. The width of the PC zone was co-driven by solar radiation (53%), humidity (27%), and soil moisture (20%). The SW phase was predominantly and negatively influenced by wind speed (86%). Finally, the MT phase was mainly related to solar radiation (64%) and soil temperature (28%). This study indicates that combining xylogenesis with a modelling approach helps the identification of possible environmental drivers in wood formation in grapevine. These findings highlight the high sensitivity of grapevine to specific micro-environmental variables and can aid in developing the potential of dendro-agronomy as a powerful diagnostic tool for assessing climate impacts in woody crops.
We describe a new fossil species belonging to the Calophyllaceae, collected from southern Baja California Sur, Mexico. This new wood is characterized by the presence of distinct growth ring boundaries, mostly solitary vessels, alternate intervessel pitting, vessel-ray parenchyma pits with reduced borders, vasicentric tracheids; non septate and septate fibers combined; axial parenchyma diffuse, diffuse-in-aggregates, scanty paratracheal and vasicentric; heterocellular rays, and large radial canals, usually one per ray, located in the center of the rays. The characteristics present in the fossil wood, although diagnostic for the Calophyllaceae, do not resemble any fossil or extant species within the family; therefore, we assign it to a new fossil species named Mammea martinezii. This is the first formal record of a fossil wood of Calophyllaceae in Mexico. The occurrence of this family in the middle Eocene (Bartonian) of southern Baja California Sur contributes to the understanding of the historical distribution of the family and its geological history and importance in forests of northern Mexico.
Wood species identification is crucial for the legal regulation of timber trade and forest conservation. Traditional wood anatomy techniques, while widely used, face challenges due to a shortage of experts. To address this issue, we have been developing automated wood identification systems utilising computer vision-based object detection models that offer promising solutions, yet their evaluation is heavily influenced by ground truth construction and confidence score adjustment. This study examines the impact of ground truth annotation strategies and detection confidence scores on model performance in detecting microscopic features of wood. Two detection models for cross-field pits in softwood and vessel groupings in hardwood were trained using YOLOv7 and evaluated using mean Average Precision (mAP). The study compares two ground truth strategies: focal-plane ground truth (FGT), which includes only sharply defined features, and extended perceptual ground truth (EGT), which incorporates visually recognisable but less distinct anatomical structures. Results indicate that EGT improves mAP performance by broadening inclusion criteria. Additionally, optimisation of confidence threshold impacts on recall, precision and mAP, which can determine the feasibility of models in the real world. To ensure comprehensive evaluation, the metrics should provide precision, recall, Average Precision (AP) and mAP. This research underscores the importance of standardised annotation criteria and robust evaluation frameworks in developing accurate detection models for anatomical features of wood, contributing to advancements in automated wood species identification.
-In an age of increasing surveillance and control of markets and trade flows, new methods for species identification of commercial timbers and other woody plant products are needed. Traditional plant anatomy has generated a vast body of knowledge on taxonomical identification. In highly processed and mixed materials such as charcoal, fibreboard board and paper, where DNA and chemotaxonomic composition is regularly destroyed or altered, the anatomical structure is often still intact. Comprehensive studies in the field of state-of-the-art mu CT analysis have shown that the use of sub-micrometre CT scanning technology can be very suitable for wood identification and other structural investigations. The current state of CT technology (resolution, working speed, feasibility) opens up various options for use in combination with other relevant key technologies, in particular machine learning and other forms of digitisation in the context of wood research. Thus, the primary objective of this methodologically oriented study is to design and implement, for the first time, an automated and modular classification pipeline that integrates machine learning with volumetric high-resolution sub-mu CT imaging for wood identification. To evaluate this approach, we conducted initial experiments using a simplified basal case, applying the method to sub-mu CT scans of softwood (Pinus sylvestris) and hardwood (Acer pseudoplatanus).
A trembling aspen (Populus tremuloides) tree growing in a boreal forest in northwestern Canada exhibited traumatised xylem tissues. The features indicated that the traumatised tissues comprised frost rings caused by late spring frost. To clarify frost ring formation characteristics, such as the year of occurrence, trunk height and direction, and severity, we analysed the xylem throughout the tree trunk. The sampled aspen tree (25 years old; tree height = 5.1 m; diameter at breast height = 3.1 cm) grew after a forest fire in 1981. Transverse sections of the tree trunk along four directions (north, south, east, and west) obtained at 20-cm intervals between the ground level and the treetop were dyed and observed via a light microscope. The spring air temperature between 0 and 1.5 m above the ground was analysed in years with frost ring formation. Frost rings occurred throughout the trunk in eight years between 1983 and 2007. Frost rings with high severity formed at 3-5-year intervals after 1986. The frost rings were less severe near the ground and treetop than in the intermediate parts. There was no significant difference in frost ring severity among the four directions. The spring air temperature increased substantially before it decreased below 0 degrees C in 2003, and subzero temperatures were recorded at 1.5 m above the ground but not at ground level. These results suggest that frost ring formation varies from one year to the next and is affected by temperature variation with height. This study provides new insights into frost ring variation throughout the trunks of trembling aspen trees and the effect of air temperature differences with height on frost ring formation.
Fossil wood from the Late Miocene of Manchar Formation in the Lower Indus Basin, the Sindh Province, Pakistan has been attributed to Terminalioxylon sp. (cf. T. eo-olivari Harsh, Sharma & Suthar) (Combretaceae). This is the first fossil evidence of this family from the Manchar Formation, exposed in the Lower Indus Basin. Terminalioxylon sp. (cf. T. eo-olivari) is characterised by the combination of the lack of growth rings, small to large intervessel pits, abundant aliform and aliform-confluent axial parenchyma, the lack of septate fibres, exclusively uniseriate rays, and the occurrence of prismatic crystals in ray cells. The mesomorphic wood traits, including vessels (75-173 mu m in tangential diameter, 6.4-7.2 per mm2) and abundant axial parenchyma, suggest that T. sp. (cf. T. eo-olivari) might be a large tropical or subtropical forest tree species. This fossil wood species provides new evidence for the forest vegetation in what is now Sindh Province during the Late Miocene. Forests predated the expansion of grassland, which occurred about 8 Mya in this region, due to global cooling and local aridification after the Middle Miocene Climatic Optimum.
The Atlantic Forest encompasses different phytophysiognomies that act as ecological filters, shaping plant species distribution. This study aimed to evaluate how the variation of secondary xylem traits varies among species in different phytophysiognomies. By analyzing 16 representative species across a continuum of five phytophysiognomies (Montane Dense Ombrophilous Forest, Submontane Dense Ombrophilous Forest, Restinga, Mangrove, and Floodplain Wetland). We identified distinct adaptive strategies in xylem anatomy that reflect both environmental heterogeneity and the evolutionary history of the taxa. Vessel wall thickness was the most variable functional trait among phytophysiognomies, highlighting its role in acclimatization. Additionally, a coordinated relationship among anatomical traits ensures a balance between safe and efficient water transport. These findings provide critical insights into the adaptive mechanisms of woody plants in tropical forests, offering perspectives on their resilience to the challenges posed by global climate change.
In a greenhouse experiment, two-year-old Ulmus laevis Pall. saplings were exposed to severe drought stress till the point when half of the saplings had died. Since nearly no morphological and physiological traits were found separating the dead saplings from the surviving ones in the same experiment, the anatomical differences defining drought embolism susceptibility were expected to play a decisive role. The cross-sectional xylem structures in fine roots, stems, and petioles were analysed and tested to find anatomical traits linked to mortality, with a special focus on vessel dimensions and tree-ring growth characteristics. However, the studied petiole, stem, and fine root xylem anatomical traits only differentiated the more drought-sensitive elm saplings in a limited way. Specifically, the dead saplings had a higher petiole xylem area and a smaller median vessel lumen diameter in the stem. Nevertheless, the growth conditions during the saplings' life histories, as reflected by the growth ring width, appear to have played an important role in drought survival. The more susceptible saplings were either those that had grown poorly or those that had grown quickly during the two years preceding the drought stress. Overall, this study reveals that the vulnerability of elm saplings to severe drought stress is largely influenced by past growth conditions, although the role of xylem structure cannot be omitted.
