Tracheid Walls Research Articles

Surface-modified composites of metal–organic framework and wood-derived carbon for high-performance supercapacitors

The renewable nature, high carbon content, and unique hierarchical structure of wood-derived carbon make it an optimal self-supporting electrode for energy storage. However, the limitations in specific surface area and electrical conductivity defects pose challenges to achieving satisfactory charge storage in wood-derived carbon electrodes. Therefore, exploring diverse and effective surface strategies is crucial for enhancing the electrochemical energy storage performance. Herein, a decoration technique for enhancing aesthetic appeal involves applying a metal–organic framework (Ni/Co-MOF) containing nickel and cobalt onto the inner walls of wood tracheids. The sequential modification steps include carbonization, oxidation activation, and acid-etching. The Ni/NiO/CoO-CW-4 electrode, made by acid-etching carbonized wood (CW) doped with nickel, nickel oxide, and cobalt oxide for 4 h, has excellent surface area and pore size distribution, high graphitization degree, and exceptional conductivity. Furthermore, surface modification optimizes the surface chemistry and phase composition, resulting in a 0.8 mm thick Ni/NiO/CoO-CW-4 electrode with an exceptionally high areal capacitance of 16.76 F cm−2 at 5 mA cm−2. Meanwhile, the fabricated solid-state supercapacitor achieves an impressive energy density of 0.67 mWh cm−2 (8.38 mWh cm−3) at 2.5 mW cm−2 (31.25 mW cm−3), surpassing representative modified wood-based carbon electrodes by approximately 2–7 times. Additionally, the supercapacitor demonstrates exceptional stability, maintaining 96.21 % of capacitance even over 10,000 cycles. The parameters presented here demonstrate a significant improvement compared to those typically observed in most modified wood-derived carbon-based supercapacitors, effectively addressing common issues of low energy density and suboptimal cycling performance with wood carbon composites.

New investigations on Cretaceous woods from the Jiaolai Basin, Shandong Province and their palaeoclimate relevance

The Jiaolai Basin of China is the southernmost edge of the distribution of the northern Jehol Biota and an important area which bears both the northern and southern palaeogeographical fauna representative species. The Laiyang flora in the Jiaolai Basin is located in the transitional region between the Early Cretaceous southern and northern flora of China. Currently, research on the plants in the transitional region between the northern and southern flora are relatively weak. Our study of specimens has enriched our understanding of the floral landscape in the transitional region between the north and south flora. Cretaceous wood fossils are well preserved in China and 66 species of 29 genera have been reported up to now, which are widely distributed in China. However, in the Cretaceous Shandong Province, there are few records of wood fossils. So far, only one genus and two species have been reported. In this paper a new material of fossil wood is described from the Early Cretaceous Zhifengzhuang Formation of Laiyang Group in Jingzhi area of Anqiu City, Jiaolai Basin, Shandong Province. The present specimen has uniseriate to triseriate pits on the radial walls of tracheids, taxodioid cross-field pitting and other characters. This discovery contributes to a better understanding of fossil wood diversity in Jiaolai Basin during the Cretaceous. Through the well preserved growth rings of the specimens, it can be inferred that the environmental paleoclimate of the Early Cretaceous in Shandong Province was generally arid, with some areas being humid.

The effect of fire on tree-ring width and tracheid dimensions of Pinus nigra

Summary Forest fires play a significant role in the growth and development of trees because they can damage the phloem and cambium. Fire injury induces the formation of fire scars that can cause xylem dysfunction. The study area is located in Taşköprü, Kastamonu (Western Black Sea of Turkiye), where two forest fires occurred in 1957 and 2020. In this study, the effect of the 1957 fire on the tree-ring widths and tracheid dimensions of Pinus nigra trees was investigated. We measured tree-ring widths and tracheid dimensions of fire-scarred (FS) and unscarred (UF) trees during four different periods: the pre-fire period (1947–1956), fire event year (1957), and post–fire periods (1958–1967 and 2011–2020). In this study, UF trees showed almost 2.5–3 times wider tree–ring widths (TRWs) than FS trees. FS and UF trees also showed great variation in tracheid dimensions in the four different periods; the average tracheid diameter (TD), lumen area (TLA), and wall thickness (TWT) values increased significantly in UF trees compared to FS trees during the fire event and post-fire periods. The average TD, TLA, and average tracheid lumen diameter (TLD) decreased during the fire and post-fire years in the FS trees. In this study, we suggest that fire injury significantly affects the tracheid dimensional traits of FS Pinus nigra trees. Our results also suggest that although Pinus nigra trees experienced serious fire damage, they continued to grow but with a decrease in tracheid size.

Coordination of pinna, petiole, and root anatomical traits in 24 tropical-subtropical fern species.

Ferns are primitive vascular plants with diverse morphologies and structures. Plant anatomical traits and their linkages can reflect adaptation to the environment; however, these remain are still poorly understood in ferns. The main objective of this study was to explore whether there was structural coordination among and within organs in fern species. We measured 16 hydraulically related anatomical traits of pinnae, petioles, and roots of 24 representative fern species from the tropical and subtropical forest understory and analyzed trait correlation networks. In addition, we examined phylogenetic signals for the anatomical traits and analyzed co-evolutionary relationships. These results indicated that stomatal density and all petiole anatomical traits exhibited significant phylogenetic signals. Evolutionary correlations were observed between the tracheid diameter and wall thickness of the petiole and between the water transport capacity of the petiole and stomatal density. Conversely, anatomical traits of roots (e.g., root diameter) showed no phylogenetic signals and were not significantly correlated with those of the pinnae and petioles, indicating a lack of structural coordination between the below- and above-ground organs. Unlike angiosperms, vein density is unrelated to stomatal density or pinna thickness in ferns. As root diameter decreased, the cortex-to-stele diameter ratio decreased significantly (enhanced water absorption) in angiosperms but remained unchanged in ferns. These differences lead to different responses of ferns to climate change and improve our knowledge of the water adaptation strategies of ferns.

Electrochemical performance enhanced by solvent infiltration strategy to increase micro-mesopores within wood tracheid walls

The utilization of wood-derived carbon thick electrodes has demonstrated remarkable structural advantages in the realm of electrochemical energy storage and catalysis. Its exceptional structural stability, mechanical strength, and well-organized pore structure position it as a promising material for self-supporting electrodes. The multi-scale cross-linking of lignin, cellulose, and hemicellulose within the wood tracheid wall establishes a convenient prerequisite for structural modification. However, the significance of dynamic nanopores on wood tracheid walls in enhancing the microporous/mesoporous structure of wood-derived carbon electrodes has been overlooked due to the focus on operability of microscale array pores and wood decomposition processes. Here, we employ a straightforward, highly efficient, and environmentally sustainable solvent infiltration strategy to enhance the nanopore content within the wood tracheid wall, ultimately resulting in a significant enhancement of the microporous/mesoporous composition within the wood-derived electrode. The charge storage capacity of wood-derived carbon electrode is doubled through the implementation of a solvent permeation modification strategy, while its abundant micro/mesoporous structure also endows it with significant potential in the field of electrocatalysis. Therefore, this thermal and solvent permeation modification strategy is anticipated to supplant the conventional acid-base etching method and offer a novel research concept for the advancement of wood-based carbon electrodes with abundant pore structure and exceptional electrochemical properties.

Synergistic Effects of Heating Platens’ Temperature and Compression Ratio on the Periodic Hot-Press Drying of Chinese Fir Lumber

The effects of periodic hot-press drying on drying behavior and mechanical damage to Chinese fir lumber were investigated by taking the heating platens’ temperature (TP) and compression ratio (Rc) as experimental factors. The temperature and pressure inside lumber were analyzed during drying process. The results were as follows. The drying rate of lumber was significantly increased with increasing TP and Rc. Scanning electron microscope (SEM) micrographs showed that bordered pit membranes, cross-field pits, middle lamella between adjacent cells, and tracheid walls were damaged after drying, and the damage became more severe with higher TP and Rc. Detachments between ray parenchyma cells and tracheids were observed at 170 °C. Nitrogen-adsorption measurement results demonstrated that more cell wall pores in the 2.5~6.2 nm pore diameter range were generated at higher TP, resulting in an enlarged specific surface area and pore volume of cell walls. These structural changes contributed to accelerating moisture migration and decreasing the drying time. Furthermore, fluctuating pressure inside lumber was the main driving force leading to moisture migration and cell tissue damage in lumber during drying. The influence of TP on internal temperature (TM) and pressure (PM) was greater than Rc. With the increase in TP from 130 to 170 °C at the Rc of 10%, the maximum TM and PM were increased by 30.90% and 39.84%, respectively. However, TP should not be too high to prevent the formation of macro-cracks caused by high pressure, which may significantly affect wood’s mechanical properties. These results provide theoretical support for periodic hot-press drying processes’ improvement and high-value utilization of Chinese fir.

Development of Spatiotemporal Whole-Stem Models for Estimating End-Product-Based Fibre Attribute Determinates for Jack Pine and Red Pine

The objective of this study was to develop spatiotemporal whole-stem wood quality prediction models for a suite of end-product-based fibre attribute determinates for jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Aiton): specifically, for wood density (Wd), microfibril angle (Ma), modulus of elasticity (Me), fibre coarseness (Co), tracheid wall thickness (Wt), tracheid radial diameter (Dr), tracheid tangential diameter (Dt), and specific surface area (Sa). Procedurally, these attributes were determined for each annual ring within pith-to-bark xylem sequences extracted from 610 jack pine and 223 red pine cross-sectional disks positioned throughout the main stem of 61 jack pine and 54 red pine sample trees growing within even-aged monospecific stands in central Canada. Deploying a block cross-validation-like approach in order to reduce serial data dependency and enable predictive performance assessments, species-specific calibration and validation data subsets consisting of cumulative moving average values were systematically generated from the 27,820 jack pine and 11,291 red pine attribute-specific annual ring values. Graphical, correlation, regression and validation analyses were used to specify, parameterize and assess the predictive performance of tertiary-level (ring-disk-tree) hierarchical mixed-effects whole-stem equations for each attribute by species. As a result, the jack pine equations explained 46, 66, 74, 63, 59, 72, 42 and 48% of the variation in Wd, Ma, Me, Co, Wt, Dr, Dt and Sa, respectively. The red pine equations explained slightly higher levels of variation except for Me: 50, 71, 31, 83, 72, 78, 56 and 71% of the variation in Wd, Ma, Me, Co, Wt, Dr, Dt and Sa, respectively. Graphical assessments and statistical metrics related to attribute and species-specific residual error patterns and goodness-of-fit, lack-of-fit and predictive error metrics, revealed an absence of systematic bias, misspecification or aberrant predictive performance. Consequently, the resultant parameterized models were acknowledged as acceptable functional descriptors of the intrinsic spatiotemporal cumulative developmental patterns of the studied end-product fibre attribute determinates, for these two pine species. Although predicted development patterns were similar between the species with the greatest degree of nonlinearity occurring before a cambial age of approximately 30 years, irrespective of attribute, jack pine exhibited a greater degree of nonlinearity in the Wd and Dt developmental trajectories, whereas red pine exhibited a greater degree of nonlinearity in the Ma, Me, Co, Wt, Dr and Sa developmental trajectories. Potential biomechanical linkages underlying the observed attribute distribution patterns, as well as the potential utility of the models in forest management, are also discussed.

A new conifer stem, Yiwupitys elegans, from the Yiwu Jurassic Forest, Hami, Xinjiang, Northwest China

Fossil wood not only provides a comprehensive understanding of the ancient floral composition and the evolution history of wood through time, but also sheds light on the paleoclimate, paleoenvironment, and paleoecology. Permineralized conifer wood commonly occurs in the Jurassic of China; however, the detailed anatomical study has been sparsely conducted on the Jurassic wood from Xinjiang Uygur Autonomous Region (Xinjiang), Northwest China. Here, we describe a unique permineralized stem, Yiwupitys elegans Gou et Feng gen. nov. et sp. nov. from the Middle Jurassic Xishanyao Formation in Naomaohu Town of Yiwu County, Hami City, Xinjiang, Northwest China. The fossil stem is preserved with pith, primary xylem, and secondary xylem. The solid pith is heterocellular and characterized mainly by clustered or isolated secretory cells and pitted parenchymatous cells at the pith periphery. The primary xylem is mesarch showing annular, helical, and scalariform thickenings on the tracheid walls from the protoxylem to the metaxylem. The secondary xylem is pycnoxylic and exclusively composed of tracheids and parenchymatous rays. Growth rings are distinct. The secondary xylem tracheids are featured commonly by bent ends overlapping each other. They have mostly uniseriate or biseriate, or partially triseriate alternately or oppositely arranged bordered pits on the radial walls and uniseriate or biseriate bordered pits on the tangential walls. The rays are uniseriate and up to sixteen cells high. There are four to eight cupressoid pits in each cross-field, arranged in the araucarioid type. Leaf traces initiate from the pith margin and possess a single vascular strand in each trace. The anatomical structures indicate that Yiwupitys elegans has a closer affinity with conifers, although it shows few characteristics of ginkgophytes. Our study shed new light on the plant diversity of the Yiwu Jurassic Forest.

Anatomical characteristics of the leaning stem in Pinus merkusii seedling

Abstract. Safitri NM, Prastiwi FW, Salsabila S, Feriawan Y, Brilianto A, Nugroho WD. 2023. Anatomical characteristics of the leaning stem in Pinus merkusii seedling. Biodiversitas 24: 3796-3802. Pinus merkusii Jungh. & de Vriese is one of the tropical conifer species. The species formed reaction wood called compression wood (CW) when the stem grows in an abnormal position. CW in stem wood is frequently found to cause several problems for utilization in the use of its products. However, there are few studies on the anatomical characteristics of reaction wood in tropical conifer. This study aimed to observe the differences in anatomical characteristics between compression (CW) and opposite (OW) woods in leaning the stem of P. merkusii seedlings and their anatomical differences compared to normal wood (NW). Approx. 1-year-old P. merkusii seedlings from a nursery in Trenggalek, East Java, Indonesia, that were naturally bent or tilted were used in the study. Anatomical characteristics of wood, namely the dimension of tracheids, rays, resin canals, and the proportion of cells were observed in the study. The results showed that CW of P. merkusii seedlings formed a rounded tracheid shape and intercellular space. The differences between CW and OW in P. merkusii seedlings were significant in terms of height of ray cells, tracheid proportion, and resin canal proportion. However, tracheid length, tracheid diameter, tracheid wall thickness, resin canal diameter and frequency, rays frequency, and ray proportion were not significantly different compared to OW and NW.

<i>XENOXYLON</i> (CONIFERALES) FOSSIL WOODS FROM THE LOWER CRETACEOUS DEPOSITS OF THE FRANZ JOSEF LAND ARCHIPELAGO

Fossil wood species Xenoxylon phyllocladoides and X. jakutiense of the Mesozoic genus Xenoxylon (Coniferales) are described from the Lower Cretaceous volcano-sedimentary deposits of Mac-Cult and Salisbury islands of the Franz Josef Land Archipelago. Fossil woods from Mac-Cult and Salisbury islands are described for the first time. Record of X. jakutiense from Salisbury Island represents the first record of this species from the island part of the Arctic. The presence of abietinean pitting on the radial walls of tracheids indicates that these species belong to the “phyllocladoides” group sensu Philippe et al. (2013), evolved from ancestral forms of Xenoxylon in the Early Jurassic. The discovery of X. phyllocladoides and X. jakutiense fossil woods in the Lower Cretaceous deposits both on the island and mainland parts of the Russian Arctic confirms the conclusions about floristic links between Franz Josef Land and the northern part of the Siberian Platform in the Early Cretaceous.

Biological decay by microorganisms in stems from the Upper Triassic Ischigualasto Formation (San Juan Province, Argentina): A striking microbial diversity in Carnian-Norian terrestrial ecosystems

We studied degradation patterns and microorganisms preserved in permineralized stems of Rhexoxylon piatnitzky, Protojuniperoxylon ischigualastense, and Agathoxylon argentinum from the Valle de la Luna Member of the Ischigualasto Formation (Upper Triassic, San Juan, Argentina). All three species show loss of middle lamella, thinning, and whitening of tracheid cell walls, and detachment of the S3 layer, consistent with selective delignification by white rot. This type of rot is the product of lignin and cellulosic degradation by Basidiomycetes and Ascomycetes. Rhexoxylon piatnitzkyi also shows small cavities, more or less circular in outline, on the wall of tracheids. This is known as soft rot and can be produced by some Ascomycetes, the anamorphic phases of diverse fungi, and tunneling bacteria. Additionally, abundant and diverse microorganisms were found. Rhexoxylon piatnitzkyi shows fragments of septate hyphae, evidence of bacterial activity, and structures of unknown affinity. Protojuniperoxylon ischigualastense presents structures common to anamorphic phases of diverse fungi, such as chlamydospores and conidiophores. Lastly, Agathoxylon argentinum bears coiled and septate hyphae, and a fan-shaped mycelium, whose significance is discussed. The microbiological study was complemented by the assessment of sedimentary and taphonomic data of the fossil-bearing beds. A gradual increment in humidity for the Valle de la Luna Member is interpreted, which concludes with a humidity peak in its upper section. This contribution represents the first detailed study of xylophagous and saprophyte micro-communities for the Ischigualasto Formation. The abundance and diversity of microorganisms described illustrate the complexity of wood-inhabiting micro-communities from the Carnian-Norian interval of Argentina.

Construction of polyaniline/MnO2 core-shell nanocomposites in carbonized wood tracheids for high-performance all-solid-state asymmetric supercapacitors

Polyaniline (PANI) nanomaterials or carbon nanotubes (CNTs) are first synthesized on the tracheid wall of activated wood carbon (AWC) to obtain PANI@AWC and CNT@AWC, respectively. Then MnO2 nanosheets are electrodeposited on the outer surface of the PANI nanomaterials to form a core-shell structure. The introduction of PANI in wood tracheids not only increases the loading of MnO2, but also improves the electrical conductivity and structural stability, and the core-shell structure can synergistically store energy. Then using the MnO2/PANI@AWC composite electrode as an anode and using CNT@AWC as a cathode, a high-performance all-solid-state asymmetric supercapacitor with high energy density and high cycling stability is successfully constructed. This supercapacitor has a wide working voltage of 0–1.8 V and a high energy density of 0.875 mWh cm−2 at 9 mW cm−2. The capacitance retention rate is as high as 93.21 % after 10,000 charge-discharge cycles. Therefore, wood-based composites with aligned tracheids have great potential in the development of high-power and high-energy-density energy storage devices.

Wood density and microfibril angle from pith to bark of a sugi cultivar (Cryptomeria japonica, Japanese cedar, Tosaaka) grown in a Nelder plot

The current stumpage price in harvesting of a 50-year-old sugi (Japanese cedar, Cryptomeria japonica) plantation is not enough to motivate forest owners to reforest. Therefore, it is vital to reduce the cost for reforestation after logging as well as for logging and wood transportation of the preceding stands. Low initial tree density has been emphasized as one of the important basic measures to reduce directly the reforestation costs. In this study, for better understanding of the mechanical properties and dimensional stability of lumbers from sugi trees grown in low initial tree density, we examined the effects of initial tree density on wood density and microfibril angle of the S2 layer in the secondary wall of tracheids in rings from pith to bark in a sugi cultivar (Tosaaka) grown in a Nelder plot (initial density zoning symbols; D (4823 trees/ha), E (3349 trees/ha), G (1615 trees/ha), H (1122 trees/ha) and J (541 trees/ha)). Ring width and latewood percentage in J tree (541 trees/ha) were significantly larger and smaller than those of other initial tree density zoning symbol trees, respectively. Average wood density and earlywood wood density in J tree (541 trees/ha) were significantly smaller than those of other initial tree density zoning symbol trees (Tukey’s honestly significant difference test (Tukey HSD), p < 0.05). However, effects of initial tree density on the microfibril angles (earlywood and latewood) in rings from pith to bark and the transition patterns of microfibril angle from earlywood to latewood in an outer ring (ring number 22) were not significant or very small. Heartwood width in H trees (1122 trees/ha) and J trees (541 trees/ha) were significantly larger than those in other initial tree density zoning symbol trees (Tukey HSD, p < 0.05). There were no significant differences of ring width, average wood density, earlywood density and microfibril angle between H trees (1122 trees/ha) and E trees (3349 trees/ha) in many rings from pith to bark (Tukey HSD, p > 0.05). Based on these results of Tosaaka, a sugi cultivar grown in a Nelder plot, it was assumed that mechanical properties and dimensional stability of lumbers from sugi trees grown in low initial tree density (1000 trees/ha) might be quite similar to those from sugi trees grown in the regular initial tree density (3000 trees/ha), although lumbers from J trees (541 trees/ha) might be different from those of sugi trees grown in the regular initial tree density (3000 trees/ha). By taking the effects of genetic factor (variation of sugi cultivars) and the interaction between genetic and environmental factor (initial tree density) into consideration, the effects of low initial tree density (1000 trees/ha) on mechanical properties and dimensional stability of lumbers from sugi plantations in Japan might be smaller than the effects recognized in Tosaaka in this study. In this study, we did not examine the effects of initial tree density on the knots and the cross grain of lumbers. Low initial tree density might increase the negative effects of knots and cross grain on mechanical properties of lumbers. However, recent wood processing technology could minimize these negative effects.

Response of Tracheid Structure Characteristics and Lignin Distribution of Taxodium Hybrid Zhongshanshan to External Stress

The Taxodium hybrid Zhongshanshan fast-growing species is susceptible to environment and gravity to form reaction wood. In this study, individual growth rings of reaction wood are used as subjects, and an individual growth ring is divided into three zones: compression zone (CZ), lateral zone (LZ), and opposite zone (OZ). The microanatomical structure and chemical properties of the tracheids in CZ, LZ, and OZ forms by the inclined or bent growth of T. Zhongshanshan are comparatively analyzed by using optical microscopy, scanning electron microscope, laser confocal microscopy, and Raman imaging techniques. In CZ, the length and diameter of compression wood (CW) tracheids decreased, and the shape of cross-sections became rounded as compared to the OZ and LZ tracheids. More notably, threaded fissures appeared on the cell wall of tracheids, and the thickness of the cell wall increased in CW. The analysis of tracheids’ cell wall structure showed that CW tracheids had a complete outer secondary wall middle (S2L) layer, but had no secondary wall inner (S3) layer. In the transition zone (TA) between CW and normal early wood, tracheids were divided into compressed and normal tracheids. Despite the compressed tracheids having a similar cell morphology to normal tracheids, they had a thin secondary wall S2L layer. Tracheids in LZ had a thin S2L layer only at the angle of the cell. No S2L layer was seen in the cell wall of OZ and CZ late wood tracheids. It can be concluded that the response of lignin deposition location to external stress was faster than the change in cell morphology. The above results help provide the theoretical basis for the response mechanism of T. Zhongshanshan reaction wood anatomical structures to the external environment and has important theoretical value for understanding its characteristics and its rational and efficient usage.

In-situ visualizing selective lignin dissolution of tracheids wall in reaction wood

As a renewable biological macromolecule with aromatic structure, lignin can serve as matrix substance to maintain cell wall integrity and is regarded as the natural biomass recalcitrance. Substantial differences in the cell wall lignin topochemistry between opposite (Ow) and compression wood (Cw) trachieds in Pinus bungeana Zucc. were visualized during [Emim][OAc] pretreatment at room temperature. The ionic liqiuds treatment induced a more obvious wall swelling for highly lignified Cw tracheids than that of Ow, while dynamic Raman spectra analysis indicated the higher lignin and carbohydrates removal for Ow tracheids. Raman imaging further revealed that both lignin and carbohydrates were dissolved simultaneously within the middle lamella and secondary wall of Ow and pretreatment has little effects on Cw tracheids wall. Moreover, it was demonstrated that lignin composition was the key factor to affect the composition dissolution. In particular, lignin G-units were selectively removed from cell corner middle lamella (52.3 %) and secondary wall (62.0 %) of Ow tracheids. When cotton fiber, as a reference was treated under the same conditions, lattice conversion moving from cellulose I to II occurred. The findings confirmed the important role of lignin compostion in the dissolution behavior of carbohydrate dominant tracheids wall.

A new conifer stem, Ductoagathoxylon tsaaganensis, from the Upper Permian of the South Gobi Basin, Mongolia and its palaeoclimatic and palaeoecological implications

Permineralised stems of Ductoagathoxylon tsaaganensis Cai, Zhang et Feng sp. nov. are described from the Upper Permian strata of the Tsaagan Tolgoy section, South Gobi Basin, Mongolia. The stems were preserved with pith and primary and secondary xylems. The pith is solid, heterocellular, and characterised by regularly arranged clusters of secretory cells at the periphery. The primary xylem is the endarch and mesarch. The tracheid walls exhibited annular, helical, and scalariform thickening from the protoxylem to metaxylem. The secondary xylem is of the Agathoxylon-type and is composed of tracheids and parenchymatous rays. The growth rings of the stems were distinct, with broad earlywood and narrow latewood. Radial tracheid pits in the secondary xylem are contiguous and alternately arranged, uni- or biseriate in the latewood, and bi- to tetraseriate in the earlywood. Rays are uniseriate and 1–7 (mostly 2–4) cells high. Each cross-field possessed 1–19 (mostly 3–9) cupressoid pits. Quantitative analysis of the growth rings indicated that the plant was likely a deciduous conifer that lived in a seasonal, temperate, and wet climate. However, a growth interruption with inflated cells was present in the secondary xylem, indicating that the tree had survived climatic damage, probably an early spring cooling event. Fungal remains, including hyphae and spores, and evident white-rot patterns in the stems revealed a common occurrence of fungal infections in the ecosystem. Our study sheds new light on the plant diversity and climatic and ecological features of the Angara flora during the Late Permian in the South Gobi Basin.

Microstructural Feature of Salvia verticillata L. vegetative and generative organs

It has been studied perspective medicinal plant Salvia verticillata L. aboveground parts vegetative and generative organs internal features. &nbsp;The aboveground parts of the plant are intensively lined with conical, multicellular (2-7) and glandular spherical trichomes; In the covering tissue of the leaf blade, stalk, and stem the ventilation system is represented by diacytic type stomata. The leaf is bifacial, amphistomatic in terms of the location of the ventilation system, while the pulp is characterized by a dorsiventral structure. In the internal structure of Salvia verticillata aboveground parts coexistence of the plate type collenchyma, polygonal structure primary parenchyma, bast fibre and collenchyma tissue&nbsp; are represented. Collateral-type vascular bundles reflected in the stem, leaf stalk, and midrib; The wood is differentiated into longitudinally arranged, spherically shaped vessels and tracheal elements, vascular tissue one -and two spiral, with porous tracheid wall thickening.

A protoxylem pathway to evolution of pith? An hypothesis based on the Early Devonian euphyllophyte Leptocentroxyla.

The Early Devonian (Emsian, 400-395 Ma) tracheophyte Leptocentroxyla tetrarcha Bickner et Tomescu emend. Tomescu et McQueen combines plesiomorphic Psilophyton-type tracheid thickenings with xylem architecture intermediate between the plesiomorphic basal euphyllophyte haplosteles and the complex actinosteles of Middle Devonian euphyllophytes. We document xylem development in Leptocentroxyla based on anatomy and explore its implications, which may provide a window into the evolution of pith. Leptocentroxyla is preserved by permineralization in the Battery Point Formation (Quebec, Canada). Serial sections obtained using the cellulose acetate peel technique document branching pattern, anatomy of trace divergence to appendages, protoxylem architecture, and variations in tracheid size and wall thickening patterns. Leptocentroxyla has opposite decussate pseudo-whorled branching and mesarch protoxylem, and represents the earliest instance of central histological differentiation in a euphyllophyte actinostele. Tracheids at the centre of xylem exhibit simplified Psilophyton-type wall thickenings and are similar in size (at the axis centre) or smaller than the surrounding metaxylem tracheids (at the centre of appendage traces). The position and developmental attributes of the simplified Psilophyton-type tracheids suggest they may have been generated by the protoxylem developmental pathway. This supports the delayed and shortened protoxylem differentiation hypothesis, which explains the evolution of pith by (1) delay in the onset of differentiation and lengthening of cell growth duration in a central protoxylem strand; and (2) shortening of the interval of differentiation of those tracheids, leading to progressive simplification (and eventual loss) of secondary wall thickenings, and replacement of tracheids with a central parenchymatous area. NAC domain transcription factors and their interactions with abscisic acid may have provided the regulatory substrate for the developmental changes that led to the evolution of pith. These could have been orchestrated by selective pressures associated with the expansion of early vascular plants into water-stresses upland environments.

Effect of drought stress on the formation and lignification of eucalyptus wood cells

Summary Environmental adaptation and cell differentiation processes are factors that influence the anatomical elements of wood. The objective of this study was to investigate the effect of water deficit on lignin composition in anatomical elements and on the characteristics of vessel-neighboring cells. Six-year-old clones of Eucalyptus urophylla and Eucalyptus grandis × Eucalyptus camaldulensis from wet and dry regions were used. All regions received a rainfall exclusion treatment. Cell wall width, cell wall thickness, and form factor of fibers close to and far from vessels were measured. In the same cells, lignin was measured in the middle lamella and vessels by a fluorescence technique. The vessel differentiation process affected cell wall thickness and lignin composition in neighboring cells. Lignin composition was increased in vessels compared to fibers or vasicentric tracheids. Middle lamella lignin was not affected by vessel differentiation or water deficit in either eucalyptus clone. E. grandis × E. camaldulensis is originally from a dry climate region and, therefore, did not suffer alterations in lignin when subjected to water stress conditions; however, this clone exhibited a higher number of vasicentric tracheids. E. urophylla is originally from a humid climate region and, when subjected to water deficit, showed increased wood lignin composition, which seems to be a strategy for better use of water resources. Alterations in lignin composition of vessel, vasicentric tracheid, and fiber cell walls resulting from exposure to water deficit conditions vary according to eucalyptus species.

Chemical and structural changes of ocote pine (Pinus oocarpa) wood caused by thermal modification

Thermal modifications alter the physical properties and improve the natural durability of wood without using chemical impregnation processes being an environmentally friendly alternative; these improvements could be made due to changes in the internal wood structure. In this investigation, changes caused to the chemical composition and microstructure of wood Pinus oocarpa by thermal modification at 170 and 190 °C were evaluated. The thermal treatment was carried out in a prototype chamber operated during the modification steps under a steam atmosphere, with a continuous flow without pressure. The evaluation of chemical changes was performed following the TAPPI standards. Using Fourier transform infrared spectroscopy (FTIR) and optical microscopy, the wood microstructure was characterized. The results showed a decrease in holocellulose contents by 7% at 170 °C and by 9% at 190 °C; lignin contents increased at 170 °C (6%) and at 190 °C (8%) and extractives were increased by 8% (170 °C) and 13% (190 °C); the changes obtained by the spectra were related to the C-H deformation in cellulose and hemicelluloses and the complex bonds of lignin carbohydrates of the -CH3 (lignin) and CH2 (carbohydrates) groups and organic acids released during thermal modification. Thickness of tracheid walls decreased in earlywood 8% (170 °C) and 22% (190 °C) and in latewood 11% (170 °C) and 14% (190 °C); lumen diameters increased in earlywood to 170 °C (14%) and 190 °C (48%) and in latewood in 14% (170 °C) an in 20% (190 °C). At 190 °C, the cell alterations were higher. Pinus oocarpa was thermally modified at 170 °C showing better wood quality in its internal structure.