Axial Parenchyma Research Articles

A global analysis of parenchyma tissue fractions in secondary xylem of seed plants.

Summary Parenchyma is an important tissue in secondary xylem of seed plants, with functions ranging from storage to defence and with effects on the physical and mechanical properties of wood. Currently, we lack a large‐scale quantitative analysis of ray parenchyma (RP) and axial parenchyma (AP) tissue fractions.Here, we use data from the literature on AP and RP fractions to investigate the potential relationships of climate and growth form with total ray and axial parenchyma fractions (RAP).We found a 29‐fold variation in RAP fraction, which was more strongly related to temperature than with precipitation. Stem succulents had the highest RAP values (mean ± SD: 70.2 ± 22.0%), followed by lianas (50.1 ± 16.3%), angiosperm trees and shrubs (26.3 ± 12.4%), and conifers (7.6 ± 2.6%). Differences in RAP fraction between temperate and tropical angiosperm trees (21.1 ± 7.9% vs 36.2 ± 13.4%, respectively) are due to differences in the AP fraction, which is typically three times higher in tropical than in temperate trees, but not in RP fraction.Our results illustrate that both temperature and growth form are important drivers of RAP fractions. These findings should help pave the way to better understand the various functions of RAP in plants.

Pliocene taxodiaceous fossil wood from southwestern Ukraine and its palaeoenvironmental implications

Mineralized wood collected from Late Pliocene strata near Gorbki village in the Transcarpathian region of Beregovo Kholmogor'e in southwestern Ukraine was anatomically studied and identified. The wood possesses distinctive anatomical features and has distinct growth rings with an abrupt transition from early- to late-wood. Wood consists of tracheids with 1–3 seriate, dominating bi-seriate, opposite pits on the radial walls and taxodioid cross-field pitting, indentures present. Rays are uni-seriate and 1 to 73 cells high. Ray parenchyma horizontal walls thin and smooth. Axial parenchyma distributed in early- and late-wood and is solitary and diffuse, with end walls nearly smooth or slightly nodular. The combination of features observed in the wood indicates it belongs to the conifer family Taxodiaceae and is most similar to modern Sequoia and assigned to the fossil genus Sequoioxylon. Comparison with species of Sequoioxylon show it is most similar to Sequoioxylon burejense, but ray tracheids were not found in our specimens. We describe the specimens here as Sequoioxylon cf. s. burejense noting this similarity. Extant Sequoia is distributed in the northern California coastal forest eco-region of northern California and southern Oregon in the United States where they usually grow in a unique environment with heavy seasonal precipitation (2500mm annually), cool coastal air and fog drip. This study supplies magafossil evidence of Sequoioxylon as an element of the Late Pliocene forest community in Ukraine and indicates a climate with heavy seasonal precipitation and fog drip.

Aptian–Albian Cupressaceae (sensu stricto) woods from Cañadón Asfalto Basin, Patagonia Argentina

This paper describes the first macrofloristic record from Los Adobes Formation (Chubut Group) in Cañadón Asfalto Basin (Patagonia, Chubut Province, Argentina). The studied fossils were recovered from the Aptian–Albian Bardas Coloradas Member, and consist of silicified woods preserved in fluvial channel deposits. One wood shows homocellular rays with smooth radial and tangential walls, diffuse axial parenchyma, tracheid pitting of the abietinoid type and cross-field pitting cupressoid usually ordered in rows and columns indicating placement within Cupressinoxylon hallei Kräusel. This fossil tree resembles some members of the extant Cupressaceae s.s., as Austrocedrus chilensis (D. Don) Pic. Serm. & Bizzarri, Pilgerodendron uviferum (D. Don) Florin, Fitzroya cupressoide (Molina) I. M. Johnst. and Libocedrus plumosa (D. Don) Druce. Due to poor preservation the other fossil wood specimen was assigned to cf. Cupressinoxylon Göppert 1850 nom. cons. prop. This is the first unequivocal record of C. hallei from the Cretaceous of South America and the oldest reliable record of the Callitroideae, indicating that this subfamily was well established since the mid-Cretaceous in the Southern Hemisphere.

Legume Fossil Woods from the Arroyo Feliciano Formation (Late Pleistocene, Northeastern Argentina): Paleobiogeographic Implications

Fil: Brea, Mariana. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro de Investigaciones Cientificas y Transferencia de Tecnologia A la Produccion; Argentina. Universidad Autonoma de Entre Rios; Argentina

Xylem plugging and postharvest longevity of cutAcacia holosericea

An inherently short vase life is a problematic characteristic of cut flowers and foliage for otherwise attractive native Australian Acacia spp. Reasons underlying the poor postharvest water uptake of cut acacia stems have been elusive. A. holosericea was used to investigate possible bacteria-induced and wound-induced xylem occlusion. The effects of bacterial-and wound-induced xylem blockage on water uptake were investigated by light and scanning and transmission electron microscopy. Observations were made on cut stems that stood into either deionised water (DIW; control) or 0.5 mM Cu2+ solution and on stems pulsed with 2.2 mM Cu2+ solution and then stood into DIW. The stem-end region of cut A. holosericea that stood into DIW or Cu2+ solution became covered with bacterial growth after 3 days. Regardless of the bacterial biofilm, the Cu2+ treated stems had improved water relations and vase life. Therefore, the biofilm had little or no effect on cut A. holosericea longevity. Further observations revealed presence of a vessel-occluding substance (gel) originating from axial parenchyma cells in direct physical contact with xylem vessels. The gel exuded into vessel lumens through pit membranes, evidently as a wound-response. Xylem occlusion by gels in A. holosericea may be especially problematic due to an abundance of secretory contact cells relative to xylem elements. Nonetheless, active wound response processes may be the key determinant of short postharvest longevity for this and possibly other cut Acacia spp. Cu2+ treatments, however, disrupted the secretory function of axial parenchyma cells thereby preventing vessel occlusion by the gels.

Comparison of density and selected microscopic characteristics of stem and branch wood of two commercial trees in Ghana

The objective of this study was to investigate density and some microscopic characteristics (fibre length, vessel lumen diameter, and vessel, fibre and parenchyma proportions) of stem and branch wood of Terminalia superba (ofram) and Pterygota macrocarpa (koto). Branch and stem wood samples were obtained from two natural forest reserves. Wood density was determined in accordance with ISO 3131, whereas the anatomical investigations followed the IAWA Committee 1989 recommendations. The results indicated that at 5 % level of significance, wood density was significantly higher (p 0.1) in the branch wood of koto than that of their respective stem wood counterparts. For both species, significant difference (p 0.1) was found in ray parenchyma proportion. Branch wood density correlated significantly and positively with only fibre (r = 0.216, p < 0.05) and axial parenchyma (r = 0.286, p < 0.05) proportions but stem wood density correlated significantly and positively with fibre length (r = 0.417, p < 0.01) and fibre proportion (r = 0.490, p < 0.01) but negatively with vessel proportion (r = −0.669, p < 0.01) and vessel lumen diameter (r = −0.291, p < 0.05). The results from the present study indicated that the position of wood in a tree (stem or branch) is a factor for consideration in processing and utilizing the two species as the fibre length, vessel lumen diameter, and vessel and fibre proportions affect the strength, porosity, leachability, natural durability and drying of the lumber.

Comparative wood anatomy of species of Psychotria L. (Rubiaceae) in Atlantic Rainforest remnants of Rio de Janeiro State, Brazil

Psychotria is the largest Rubiaceae genus and one of the most abundant in the Atlantic Rainforest of Rio de Janeiro State. The present work aims to characterize and compare the wood of nine of these species. ThePsychotria wood were characterized by: slightly distinct growth rings; diffuse porosity; solitary vessels or on radial multiples of 2-6 or clusters of 3-5 vessel elements, with terminal and lateral simple perforation plates and vestured and alternate intervessel and vessel-ray pits; septate fiber-tracheids; and rare axial parenchyma. Although, the wood anatomy of thePsychotria may be considered homogeneous, the statistical analyses, based on qualitative and quantitative features, allowed the segregation of the species and indicated the importance of habit (arboreous or shrubby) on the wood anatomy of the species. It is worth mentioning that the sampling was realized in only one studied site (Ilha Grande), which contributed to the conclusion that the wood characteristics are more related to the specificities of each studied taxon than to with environmental variations.

Secondary phloem diversity and evolution in Bignonieae (Bignoniaceae).

Phloem evolution has been explored in the literature across very broad scales, either for vascular plants as a whole or for major plant groups, such as the monocotyledons or the former dicotyledons. However, it has never been examined in a way that would elucidate evolutionary shifts leading to the diversification of phloem in single lineages. Therefore, the present study explores in detail the patterns of phloem evolution in the tribe Bignonieae (Bignoniaceae). This group represents a particularly good model for phloem studies since it is known to have a very conspicuous and diverse phloem. A total of 19 phloem characters were coded in 56 species from all 21 genera currently recognized in the tribe Bignonieae, accounting for phloem wedge growth and for all the anatomical cell diversity encountered in the phloem. Phloem evolution was explored by reconstructing ancestral character states using maximum-likelihood assumptions with a time-calibrated molecular phylogeny for the group. Directionality and the effect of phylogenetic transformations in the current variation of quantitative traits and evolutionary correlations of selected discrete phloem traits were also tested under a maximum-likelihood approach. Individual phloem features are quite diverse in the tribe, but generally conserved within smaller clades. Contrasting phloem patterns were found when comparing major groups, with certain lineages having the phloem marked by a background of phloem fibres where all other cells are embedded, tangentially arranged sieve tubes and sieve-tubecentric parenchyma. In contrast, other lineages exhibited a scarcely fibrous phloem, regularly stratified phloem, sieve tube elements in radial or diffuse arrangement, and diffuse parenchyma. We found signals of directional evolution in fibre abundance and number of sieve areas, which increased in the 'Fridericia and allies extended clade' and decreased in the 'Multiples of four extended clade', resulting in no signal of directionality when the whole Bignonieae was considered. In contrast, no indication of directional evolution was found for the axial parenchyma, either in single clades within Bignonieae or in the entire tribe. Positive correlation was found between sieve element length and both sieve plate type and the presence of a storied structure. Correlated evolution was also found between fibre abundance and several traits, such as sieve tube arrangement, sieve plate type, parenchyma arrangement, ray lignification and number of companion cells. The secondary phloem of Bignonieae is extremely diverse, with sister lineages exhibiting distinct phloem anatomies derived from contrasting patterns of evolution in fibre abundance. Fibre abundance in the tribe has diversified in correlation with sieve tube arrangement, sieve tube morphology, number of companion cells and parenchyma type. The results challenge long-standing hypotheses regarding general trends in cell abundance and morphological cell evolution within the phloem, and demonstrate the need to expand studies in phloem anatomy both at a narrow taxonomic scale and at a broad one, such as to families and orders.

First record of Styracoxylon (Styracaceae) from Southern Hemisphere: Arroyo Feliciano Formation (Upper Pleistocene), Entre Ríos, Argentina

A new species, Styracoxylon thyllosum sp. nov., is described from the Upper Pleistocene Arroyo Feliciano Formation of the Gualeguay Basin in eastern Argentina. It is the first unequivocal record of the Styracoxylonvan der Burgh (1978) in South America and was previously known only from the Pliocene of the Rhine area, Netherlands. This fossil specimen was recovered in the Consorcio Paso Sociedad Locality (Federal, Entre Ríos, Argentina). The new fossil species is characterized by growth ring boundaries distinct, with diffuse-porous wood. Vessels are mostly in radial multiples of 2–6 elements, occasionally solitary and rarely in clusters. Tylosis is abundant. Perforation plates are usually scalariform (5–20 bars) and rarely simple. Intervessel pits are small, bordered, and alternate to opposite. Rays are frequently 2–4 (6) seriate and rarely uniseriate, heterocellular, and of two distinct ray sizes. Fibers are non-septate, with distinctly bordered pits, and rounded to hexagonal in outline.The axial parenchyma is apotracheal diffuse and diffuse-in-aggregates, and in strands of 8–12 cells. Vascular tracheids possibly present. Wood anatomical features suggest a relationship with Styracaceae, and the fossil specimen shows affinity with the extant genus Styrax Linnaeus.

Anatomical properties of Eucalyptus grandis wood and transition age between the juvenile and mature woods

The present study is aimed at evaluating the anatomical characteristics of Eucalyptus grandis wood and the transition age between the juvenile and mature woods. Four trees of 23-year-old E. grandis were used. The juvenile, transition and mature wood zones were found by fiber length measurement from the pith to the bark. Samples were taken from juvenile wood, transition wood and mature wood and the anatomical properties of the wood were determined. The results showed that: (1) the fiber length, cell wall thickness, slenderness ratio, cell wall fraction and tangential vessel diameter increase from pith to bark; (2) fibers, axial parenchyma, ray parenchyma cells and vessels are equally distributed from pith to bark; (3) the transition zone between juvenile and mature wood occurs between the age of 8 and 13 years.

Comparative wood anatomy of 56 species of Lauraceae from Yunnan, China

Wood anatomy of 56 species from 11 genera of Lauraceae collected from Yunnan, China were investigated by light and scanning electron microscopy. Detailed descriptions and comparisons of wood anatomy of different species are given in the paper to help better identification of Lauraceae wood. The qualitative and quantitative data show that wood structures are very similar among the Lauraceae studied. They are almost diffuse-porous, mainly solitary, minority radial, or diagonal multiples. Vessels have simple perforation and scalariform perforation, and the bars of scalariform perforation have bifurcations. The intervessel pits are almost alternate. Wood rays are uniseriate and multiseriate, with the former being relatively rare. All species have axial parenchyma, most of which are vasicentric. The species of Beilschmiedia and Syndiclis marlipoensis also have marginal parenchyma. Oil and mucilage cells are common in axial parenchyma and ray cells. Wood fibers are composed of libriform fibers and fiber tracheids. Many species have abundant septate fibers. Individual differences are found in several species, which may be related to genetic or environmental factors. We have roughly concluded that Beilschmiedia and S. marlipoensis have a close affiliation for they both have simple perforated plates and marginal parenchyma but with no septate fibers. Almost all species of Litsea, Neolitsea, and Actinodaphne obovata have septate fibers, simple and scalariform perforate plate, and scanty paratracheal and vasicentric parenchyma, indicating that they might be sister taxa.

Seasonal variation in formation, structure, and chemical properties of phloem in Picea abies as studied by novel microtechniques.

Phloem production and structural development were interlinked with seasonal variation in the primary and secondary metabolites of phloem. Novel microtechniques provided new perspectives on understanding phloem structure and chemistry. To gain new insights into phloem formation in Norway spruce (Picea abies), we monitored phloem cell production and seasonal variation in the primary and secondary metabolites of inner bark (non-structural carbohydrates and phenolic stilbene glucosides) during the 2012 growing season in southern and northern Finland. The structure of developing phloem was visualised in 3D by synchrotron X-ray microtomography. The chemical features of developing phloem tissues isolated by laser microdissection were analysed by chemical microanalysis. Within-year phloem formation was associated with seasonal changes in non-structural carbohydrates and phenolic extractive contents of inner bark. The onset of phloem cell production occurred in early and mid-May in southern and northern Finland, respectively. The maximal rate of phloem production and formation of a tangential band of axial phloem parenchyma occurred in mid-June, when total non-structural carbohydrates peaked (due to the high amount of starch). In contrast, soluble sugar content dropped during the most active growth period and increased in late summer and winter. The 3D visualisation showed that the new axial parenchyma clearly enlarged from June to August. Sub-cellular changes appeared to be associated with accumulation of stilbene glucosides and soluble sugars in the newest phloem. Stilbene glucosides also increased in inner bark during late summer and winter. Our findings may indicate that stilbene biosynthesis in older phloem predominantly occurs after the formation of the new band(s) of axial parenchyma. The complementary use of novel microtechniques provides new perspectives on the formation, structure, and chemistry of phloem.

ANATOMIA DO LENHO DE RAIZ, TRONCO E GALHO DE BARBATIMÃO (Stryphnodendron adstringens (Mart) Coville)

Objetivou-se analisar o lenho de raiz, tronco e galho de barbatimão, Stryphnodendron adstringens em área de cerrado, no município de Lavras, MG. Amostras de lenho do tronco e do galho foram retiradas a 0, 25, 50, 75 e 100% da altura total do tronco e comprimento total do galho. Amostras de lenho das raízes foram retiradas a 40 cm de profundidade do solo. Qualitativamente o lenho do barbatimão possui camadas de crescimento distintas para o tronco e galho; na raiz, encontram-se pouco definidas. Porosidade difusa. Placas de perfuração simples. Pontoações intervasculares e raio-vasculares, areoladas, alternas e com guarnições. Parênquima paratraqueal vasicêntrico. Raios predominantemente unisseriados, apresentando raios multisseriados. Os raios são heterocelulares, onde o corpo do raio é formado por células procumbentes e margens com células quadradas e eretas. Observaram-se, raios homogêneos formados apenas por células procumbentes. Presença de cristais nas células dos parênquimas axiais, radiais e nas fibras. Quantitativamente, as características relevantes para o lenho foram: maior frequência de vasos para o galho; paredes das fibras mais espessas no lenho de raiz e raio mais largo no tronco.

Broad Anatomical Variation within a Narrow Wood Density Range--A Study of Twig Wood across 69 Australian Angiosperms.

ObjectivesJust as people with the same weight can have different body builds, woods with the same wood density can have different anatomies. Here, our aim was to assess the magnitude of anatomical variation within a restricted range of wood density and explore its potential ecological implications.MethodsTwig wood of 69 angiosperm tree and shrub species was analyzed. Species were selected so that wood density varied within a relatively narrow range (0.38–0.62 g cm-3). Anatomical traits quantified included wood tissue fractions (fibres, axial parenchyma, ray parenchyma, vessels, and conduits with maximum lumen diameter below 15 μm), vessel properties, and pith area. To search for potential ecological correlates of anatomical variation the species were sampled across rainfall and temperature contrasts, and several other ecologically-relevant traits were measured (plant height, leaf area to sapwood area ratio, and modulus of elasticity).ResultsDespite the limited range in wood density, substantial anatomical variation was observed. Total parenchyma fraction varied from 0.12 to 0.66 and fibre fraction from 0.20 to 0.74, and these two traits were strongly inversely correlated (r = -0.86, P < 0.001). Parenchyma was weakly (0.24 ≤|r|≤ 0.35, P < 0.05) or not associated with vessel properties nor with height, leaf area to sapwood area ratio, and modulus of elasticity (0.24 ≤|r|≤ 0.41, P < 0.05). However, vessel traits were fairly well correlated with height and leaf area to sapwood area ratio (0.47 ≤|r|≤ 0.65, all P < 0.001). Modulus of elasticity was mainly driven by fibre wall plus vessel wall fraction rather than by the parenchyma component.ConclusionsOverall, there seem to be at least three axes of variation in xylem, substantially independent of each other: a wood density spectrum, a fibre-parenchyma spectrum, and a vessel area spectrum. The fibre-parenchyma spectrum does not yet have any clear or convincing ecological interpretation.

The Delignification Pattern of Ailanthus excelsa Wood by Inonotus hispidus (Bull.: Fr.) P. Karst.

In vitro laboratory decay tests on Ailanthus excelsa Roxb. wood revealed that I. hispidus exhibits a combination of both white-rot and soft-rot patterns of wood decay. Early stages of wood decay showed dissolution of the middle lamella as well as defibration and localized delignification of fiber walls; vessels, axial, and ray parenchyma remained unaltered. Delignification commenced from the middle lamellae at the cell corners without any marked effect on the primary and secondary wall layers. In later stages of growth, the species produces typical soft-rot decay pattern by forming erosion channels through the S2 layers of fiber walls, transverse bore holes in the cell walls, and erosion channels alongside/following the orientation of cellulose microfibrils. The rays showed signs of cell wall alterations only after the extensive damage to the fiber walls. After 120 days of incubation, the vessels also showed localized delignification, the erosion of pits, and separation from associated xylem elements. The extensive weight losses under natural and in vitro decayed wood as well as the very soft nature of severely degraded wood indicate that I. hispidus alters wood strength and stiffness.

First extra-Patagonian record of Podocarpaceae fossil wood in the Upper Cenozoic (Ituzaingó Formation) of Argentina

The main objective of the present paper is to describe a new genus and species of Podocarpaceae fossil wood from the Upper Cenozoic Ituzaingó Formation, Paraná Basin, Argentina, based on a detailed description of the secondary xylem. This specimen, Prumnopityoxylon gnaedingerae Franco & Brea gen. nov. & sp. nov., is the first fossil wood referable as coniferous from northeastern Argentina. This fossil resembles extant Prumnopitys Phil. (Podocarpaceae), sharing the following anatomical features: slightly distinct growth rings; the absence of axial parenchyma; uniseriate and homocellular rays; uniseriate or biseriate, opposite or sub-opposite, separate or contiguous tracheid pitting; and cupressoid or taxodioid cross-field pitting. The presence of this Podocarpaceae fossil from the Ituzaingó Formation indicates that the distribution of this family was more widespread and probably continuous in South America in the past. It also provides new evidence for the hypothesis of its wide distribution in northeastern Argentina during the Cenozoic.

Description anatomical macroscopic wood forest species of eigth market in the municipality of Altamira-PA, BRAZIL

The Para is the largest producer of tropical timber, followed by Mato Grosso and Rondonia, and is currently the second largest exporter of wood from Brazil. This fact is linked mainly to abundant demand for wood. Therefore, the objective of this study was to define anatomical description of eight forest wood species traded in the municipality of Altamira, PA. The work was developed in the laboratory of Technology, Faculty of Forestry of the Federal University of Para, Altamira campus. To describe the macroscopic structure of wood were used specimens with the size of 2x2x2cm in the plans (transverse, tangential longitudinal and radial longitudinal. The species studied were Angelim-amargoso, Angelim-vermelho, cumaru, curupixa, jatoba, macaranduba, muiracatiara and piqui. The structures that showed greater differences between the species studied were the axial parenchyma and the growth layers. Addressed such structures will serve as an aid to identification and recognition of these woods for marketing in the timber market.

Anatomical variation of teakwood from unmanaged mature plantations in East Timor

Teak (Tectona grandis L. f.) is an important native species of Southeast Asia, producing an excellent quality wood with high demand in the world market contributing positively to development and economic growth of the countries. There are few published studies on the anatomical variability of teak wood from East Timor. The wood anatomical characterization and its within-tree variation were studied in three axial and radial positions of trees from an unmanaged pure stand. The wood is semi-ring-porous to ring-porous. The vessels are solitary and grouped, with 206 and 89 µm diameter (earlywood and latewood) and 259 µm length. Axial parenchyma is paratracheal unilateral and marginal. Rays are homocellular and heterocellular, varying between 241 and 1293 µm in height. Fibers, the most abundant tissue (52 %), had a mean fiber length, width and wall thickness of 1.15 mm, 28 and 6 µm, respectively. The anatomical features of teak wood differ from those reported for other origins in considerably smaller vessels and thicker walled fibers. Longitudinal variation showed a decrease of vessel area, fiber size, and an increase of vessel frequency, parenchyma and ray proportions towards the top of the tree. Radially vessel size, fiber length and wall thickness tended to increase with cambial age.

Histological and ultrastructural alterations in the Ailanthus excelsa wood cell walls by Bjerkandera adusta (Willd.) P. Karst

Ailanthus excelsa Roxb. requires less care than other species and thrives in arid and semi-arid regions. Therefore, it becomes an important choice for forestry programs. Young branches of these trees are frequently invaded by the fungus Bjerkandera adusta (Willd.) P. Karst. The main aims of this study were to characterize the wood decay pattern and evaluate the extent of damage caused by the fungus. Infected samples were studied using light microscopy, confocal laser scanning microscopy, transmission electron microscopy, and scanning electron microscopy. Wood of the dead branches became pale white and very soft. In vitro decayed wood showed extensive weight loss of wood blocks (68.6%) at the end of three months. In the xylem, fibres were the most severely affected cell types, whereas wall structure of the axial parenchyma remained virtually unaltered. Unlike axial parenchyma, walls of the ray cells formed several boreholes and finally collapsed in the advanced stage of decay. By contrast, the middle lamella of all the xylem elements remained intact even at the end of three months. In the early stages of infection, vessels appeared to be resistant to the fungal action but they also became eroded at the advanced stage. The degradation pattern showed anatomical characteristics of both the white-rot and soft-rot type of decay. Thinning of walls from the lumen side and appearance of U-notches resembles white-rot decay, while tunnels through the S2 layer of the fibre wall added the characteristics of the soft-rot decay pattern. Extensive weight loss of wood blocks following infection suggests B. adusta is an aggressive wood-degrading fungus.

The frequency of ray and axial parenchyma versus tree-ring width in silver fir (Abies alba Mill.)

Key message Ray and axial parenchyma frequency, observed in cross-sections of matureAbies albatrunks is not related to tree-ring width.