Showing papers in "Iawa Journal in 2006"

Trephor: a new tool for sampling microcores from tree stems

Abstract: SUMMARY Detailed analyses of cambium activity and wood formation during growth need repeated sampling of newly formed xylem. In order to be minimally invasive, wood samples are extracted as microcores. Despite the research done on xylem cell development and the increasing interest in intra-annual studies of xylogenesis, few tools are available for microcore sampling. Methods originally designed for other purposes have often been used, but no details are available on their efficiency and usefulness. Information is also lacking on laboratory preparation techniques for cell analysis of tree-ring formation, leading to difficulties in carrying out these experiments. The advantages and limits of the tools used up to now are described. A new tool, named Trephor (patent pending n° PD2004A000324), specifically designed for long-lasting use is presented. Trephor is chisel-shaped for a fast recovery of 2 mm diameter microcores. The cutting tube is inserted into the wood using a hammer and no other accessory is required. Simple technical characteristics allow high quality samples to be collected from both softwood and hardwood species with minimum damage to the sampled trees. Trephor was tested during the 2004 growing season, demonstrating good resistance to wear and tear and mechanical stress. Embedding the microcores in paraffin for fast section preparation is described.

Assessment of cambial activity and xylogenesis by microsampling tree species: an example at the alpine timberline

Abstract: SUMMARY Mechanisms of cell production and maturation and dynamics of xylem formation have been widely studied in trees in order to better characterize stem radial growth. Histological analyses have been used in this study to describe cambial activity and xylem cell differentiation in Larix decidua, Pinus cembra and Picea abies at the Alpine timberline. Wood microcores were collected weekly from April to October 2003 and cross sections prepared to distinguish xylem cells of the growing tree ring and to determine the number of cells in the cambial zone, radial cell enlargement, secondary wall thickening and lignification and the number of mature tracheids. The anatomical changes characterizing the phases of xylem cell production and differentiation during the year are described and discussed. All species showed the same trend of xylem formation. Three delayed bell-shaped curves and an S-shaped curve were observed for cambium, enlarging and wall thickening cells and mature cells, respectively. Cells divided in the cambial zones from April-May to August, depending on the species. From 100 to 130 days were required to complete cell differentiation. Tree-ring formation ended during September. The average periods spent on radial enlargement, and secondary cell wall thickening and lignification were estimated at 7–10 and 20–25 days, respectively.

Tension wood and opposite wood in 21 tropical rain forest species : 1. Occurence and efficiency of the G-layer

Abstract: SUMMARY Wood samples were taken from the upper and lower sides of 21 naturally tilted trees from 18 families of angiosperms in the tropical rain forest in French Guyana. The measurement of growth stresses ensured that the two samples were taken from wood tissues in a different mechanical state: highly tensile stressed wood on the upper side, called tension wood, and lower tensile stressed wood on the lower side, called opposite wood. Eight species had tension wood fibres with a distinct gelatinous layer (G-layer). The distribution of gelatinous fibres varied from species to species. One of the species, Casearia javitensis (Flacourtiaceae), showed a peculiar multilayered secondary wall in its reaction wood. Comparison between the stress level and the occurrence of the G-layer indicates that the G-layer is not a key factor in the production of high tensile stressed wood.

Tension wood and opposite wood in 21 tropical rain forest species 2. Comparison of some anatomical and ultrastructural criteria

Abstract: The anatomy of tension wood and opposite wood was compared in 21 tropical rain forest trees from 21 species belonging to 18 families from French Guyana. Wood specimens were taken from the upper and lower sides of naturally tilted trees. Measurement of the growth stress level ensured that the two samples were taken from wood tissues in a different mechanical state: highly tensile-stressed wood on the upper side, called tension wood and normally tensile-stressed wood on the lower side, called opposite wood. Quantitative parameters relating to fibres and vessels were measured on transverse sections of both tension and opposite wood to check if certain criteria can easily discriminate the two kinds of wood. We observed a decrease in the frequency of vessels in the tension wood in all the trees studied. Other criteria concerning shape and surface area of the vessels, fibre diameter or cell wall thickness did not reveal any general trend. At the ultrastructural level, we observed that the microfibril angle in the tension wood sample was lower than in opposite wood in all the trees except one (Licania membranacea).

Seasonal variation in wood formation of cedrela fissilis (meliaceae)

Abstract: Cambial activity and periodicity of secondary xylem formation in Cedrela fissilis, a semi-ring-porous species, were studied. Wood samples were collected periodically from 1996 to 2000. The phenology was related to climate data of the region. The cambium has one active and one dormant period per year. The active period coincides with the wet season when trees leaf-out. The dormant period coincides with the dry season when trees lose their leaves. Growth rings are marked by parenchyma bands that begin to be formed, together with the small latewood vessels, just before the cambium becomes dormant at the beginning of the dry season. These bands are added to when the cambium reactivates in the wet season. At this time, the large earlywood vessels of the growth rings are also formed. As these bands consist of both terminal and initial parenchyma, we suggest the general term marginal bands be used to describe them. The growth layers vary in width among and within the trees.

Within-Tree Variation in Wood Fibre Biometry And Basic Density of the Urograndis Eucalypt Hybrid (Eucalyptus Grandis × E. Urophylla)

Abstract: Within-tree variations in fibre length, width, wall thickness and wood basic density of Eucalyptus grandis × E. urophylla (urograndis) were studied in five 6.8-yr-old seedling trees and five 5.6-yr-old trees from one clone from Brazil. Samples were taken at 5%, 25%, 35%, 55%, 65% and 90% of stem height and five radial positions (10%, 30%, 50%, 70% and 90% of radius). The tree average fibre length, width and wall thickness were in seed and clone trees: 0.955 mm and 1.064 mm, 18 μm and 20 μm, 3.6 μm and 4.4 μm respectively. The axial variation of fibre dimensions was very low, while there was a consistent but small increasing trend from pith to periphery. The basic density ranged from 397–464 kg/m3 to 486–495 kg/m3 respectively in seedling and clone trees with a low variation along the stem. In comparison with other eucalypt pulpwood, e.g. E. globulus, the urograndis hybrid showed similar fibre dimensions and lower basic density. Overall the within-tree variation of these wood properties was low and age had a small impact on the variation of density and fibre dimensions.

Wood Specific Gravity of Trees in Amazonian White-Water Forests in Relation to Flooding

Abstract: Wood specific gravity (SG) was analysed from wood cores of 180 individuals belonging to 58 common upper canopy tree species of late successional white water (varzea) forests in the Mamiraua Sustainable Development Reserve, Central Amazon Basin We tested for a SG gradient of trees along the flood gradient Mean SG in the low varzea was 062 g cm-3, in the high varzea 057 g cm-3 SG tended to increase with height and duration of flooding In the two species that occurred in both forest types (Hevea spruceana, Tabebuia barbata) SG was significantly lower in the high varzea trees Therefore, height and duration of flooding seem to be important factors influencing growth and wood properties in varzea trees In addition, SG variation depended on the core section and to a lesser extent on tree diameter and height Compared to trees in Amazonian upland ecosystems, SG of the varzea trees was lower than SG in Central and Eastern Amazonian terra firme, but was within the same range reported for Western Amazonian terra firme

Magnetic Resonance Micro-Imaging of Xylem Sap Distribution and Necrotic Lesions in tree Stems

Abstract: SUMMARY To get high quality magnetic resonance (MR) micro-images for the physiological and anatomical investigation of tree stems, the imaging with various combinations of parameters was tested on a Signa VH/i 3.0 T MR imaging system (General Electric Medical Systems). Proton density and T2 weighted spin echo (SE) sequences are commonly used to detect areas with abundant water. Cambial zone and the area consisting of water-filled conduits looked whitish in the MR images of healthy Pinus densiflora and Quercus serrata stems that were obtained by these sequences. In the MR images of diseased P. densiflora that had been inoculated with a wilt pathogen, Bursaphelenchus xylophilus, the area dehydrated as a result of embolism appeared pitch-black. In the images of diseased Quercus crispula saplings, that had been inoculated with the wilt pathogen Raffaelea quercivora, the dehydrated xylem was shown as a dark area. The T1 weighted SE or gradient echo (FSPGR) sequence, that is used to detect fat and protein distribution, provided high intensity MR signals for the pathogenic heartwood and necrotic areas resulting from fungal activity. The resolution of MR images obtained by SE sequences was estimated 100–150 μm from the FOV and image size. The data sets obtained by the FSPGR sequence that consist of 0.8 mm thick serial sections enables the three-dimensional analysis of the affected area. This technique is helpful for detecting the water distribution and areas affected by pathogenic microorganisms in living tree stems.

Cambial Variant in the Stem of Serjania Corrugata (Sapindaceae)

Abstract: The establishment of the cambial variant and the development of the stem of Serjania corrugata Radlk. (Sapindaceae) was analyzed. In the early stages of development, the stem is lobed, with five lobes and five furrows in cross section. Around the fourth internode, each lobe has a vascular arc with one or two more developed central vascular bundles, two lateral bundles and phloem in the interfascicular regions. Procambial strands are also found in perimedullary position, producing only phloem elements. At this stage, the beginning of the cambial activity can be seen in the central vascular bundle in each lobe. This activity then extends to the lateral vascular bundles and to the perimedullary phloem. Parenchymatic cells, located between the vascular ring of the lobe and the perimedullary phloem, dedifferentiate and initiate meristematic activity, uniting these two regions. The development of xylem masses (one in each lobe) that characterizes the adult stem results from this cambial activity. The development of the cambial variant in S. corrugata is quite similar to that previously described in S. elegans Cambess.

Eccentric growth but no compression wood in a horizontal stem of cycas micronesica (cycadales)

Abstract: SUMMARY A single 1.41-m-long trunk of Cycas micronesica K.D. Hill was found growing horizontally in natural habitat on the island of Guam. Transverse sections of the trunk showed enhancement of secondary vascular tissues on the lower side by the production of more arcs of accessory vascular cambia and more parenchyma as compared to the upper side. Xylem tracheids were similar in upper and lower sides. There was no evidence of compression wood tracheids as seen in conifers.

Tree-Ring Anomalies in Toona Ciliata

Abstract: New increment core samples of Toona ciliata collected in the Australian tropics and subtropics compared to already existing material from the Upper Kangaroo Valley, near Sydney exhibit distinct differences in tree-ring structures. This necessitated a closer examination of the wood anatomy, possible false rings and the speciesʼ crossdating capacity in northeast Australia. During tree-ring analysis two growth anomalies (extensive zones of narrow and indistinct rings) and three types of false rings were discovered which complicated crossdating. However, in growth experiments only one type of false ring could be induced artificially by totally defoliating young trees. It was possible to alter their phenological performance by artificially changing the environmental conditions. Visual crossdating of samples originating from northeast Australia was feasible within and between trees. For selected years a positive relationship between ring width and precipitation data was found.

Annual Growth Rings in a Sample of Hymenaea Courbaril

Abstract: Several tropical tree species form regular growth rings that may be annual and thus be useful in paleoclimate reconstructions. Regular growth rings were observed in one stem disk of the tropical legume Hymenaea courbaril harvested near the city of David, Panama. By comparison to annual reference Δ14C values from temperate tree wood and air, Δ14C values from the growth rings in this H. courbaril sample indicated the rings were annual. During this study, H. courbaril was also observed to translocate recently produced photosynthate into older growth rings as sapwood is converted to heartwood. This process alters the overall Δ14C values of these transitional growth rings as organic carbon with a higher Δ14C content is translocated into growth rings with relatively lower Δ14C content. Proper chemical pretreatment can recover the original cellulose Δ14C content.

Histochemical study of the chemical composition of vestured pits in two species of eucalyptus

Abstract: We analyzed the chemical composition of vestures of vessel elements and wood fibres of Eucalyptus camaldulensis and Eucalyptus globulus by ultraviolet (UV) microscopy, transmission electron microscopy (TEM) after staining with potassium permanganate (KMnO4) or the PATAg reaction, and field-emission scanning electron microscopy (FE-SEM). Samples were treated with dilute solutions of NaOH at various concentrations. Before treatment with alkali, the vestures on the secondary walls of vessel elements and wood fibres were visible on UV micrographs taken at 280 nm and were strongly stained by KMnO4. Vestures were strongly stained by the PATAg reaction in samples that had been treated with 0.1% NaOH. However, treatment with higher concentrations of NaOH dissolved the vestures. FE-SEM observations showed that the process of dissolution of vestures during alkali extraction differed between the two species. It appears that vestures in Eucalyptus woods consist mainly of alkali-soluble polyphenols and polysaccharides. In addition, the chemical composition of vestures may differ between the two species of Eucalyptus that we examined.

Within-stem water distribution in living trees of some conifers

Abstract: Water distributions within living stems of 11 species from three conifer families were observed with soft X-ray photography. The moisture contents at breast height of the trees were also measured. In all but one case, sapwood was almost saturated with free water. Intermediate wood, which was a narrow white band located between the sapwood and heartwood, was generally common in species with coloured heartwood. In heartwood, water distribution varied not only among species, but also within species, and even within a stem. In seven of the 11 species investigated, well-developed wetwood (the phenomenon of free water accumulated in heartwood) was observed. The frequent presence of wetwood led to the conclusion that it was a common feature in some groups of conifers. It is suggested that the view that wetwood is an abnormal feature may be incorrect because so far wetwood surveys have only focused on a few species that are important for forestry, e.g., hard pines. An extensive survey of many specimens belonging to various species is required to understand the mechanism of wetwood development.

Impact of Water Stress on the Sapwood Anatomy And Functional Morphology of Calligonum Comosum

Abstract: This investigation reports the impact of water stress on some anatomical traits of sapwood and other functional morphological features of green assimilatory shoots of Calligonum comosum L'Her. (Erta), a good source of fuel wood. The major findings of the study are that in this species drought makes for: a) narrower vessels both in earlywood and latewood, b) thicker vessel walls, c) longer vessel elements and fibers, d) a higher frequency of small latewood vessels and a lower frequency of large earlywood vessels, e) narrower growth rings, f) a lower total fraction of vessels per xylem area, g) higher wood density, h) narrower depth of conducting phloem, i) higher specific mass of green photosynthetic shoots, and j) a lower chlorophyll content. Extremely narrow vessels arranged in radial files in latewood were recognized having 40% increased volume fraction in nonirrigated plants. This adaptation is believed to play an important role in the species survival during hot summer months.

Alterations in Vessel Size in Twigs Of Quercus Robur and Q. Petraea Upon Defoliation and Consequences For Water Transport Under Drought

Abstract: In the complex of natural factors responsible for damage to the Central European oak species Quercus robur and Q. petraea, repeated defoliation and drought are considered the most important ones. To investigate the impact of these factors on xylem anatomy and hydraulic conductance, saplings of both species were manually defoliated in the spring of two consecutive years, and equal fractions of defoliated and control saplings were subjected to drought stress in the third year of the study. Defoliation did not significantly reduce the annual ring width of the twigs, but in the twigs of Q. robur it resulted in a significant reduction of the cross-sectional area of early- and latewood vessels, and in a shift in the distribution of the earlywood vessel cross-sectional areas towards smaller size classes in the year after the first defoliation. In the earlywood of Q. petraea twigs, repeated defoliation led to a significant increase in the cross-sectional vessel areas and to a shift in their distribution towards larger size classes. No significant differences in the percentage loss of hydraulic conductance (PLC) occurred between trees that had been defoliated in two successive years prior to the drought experiment and control trees. However, PLC was significantly increased by drought. The different responses of the oak species are attributed to their different capability to recover from the applied stress factors.

Anatomical Characteristics and Ecological Trends in the Xylem and Phloem of Brassicaceae and Resedacae

Abstract: The xylem and phloem of Brassicaceae (116 and 82 species respectively) and the xylem of Resedaceae (8 species) from arid, subtropical and temperate regions in Western Europe and North America is described and analysed, compared with taxonomic classifications, and assigned to their ecological range. The xylem of different life forms (herbaceous plants, dwarf shrubs and shrubs) of both families consists of libriform fibres and short, narrow vessels that are 20–50 μm in diameter and have alternate vestured pits and simple perforations. The axial parenchyma is paratracheal and, in most species, the ray cells are exclusively upright or square. Very few Brassicaceae species have helical thickening on the vessel walls, and crystals in fibres. The xylem anatomy of Resedaceae is in general very similar to that of the Brassicaceae. Vestured pits occur only in one species of Resedaceae.Brassicaceae show clear ecological trends: annual rings are usually distinct, except in arid and subtropical lowland zones; semi-ring-porosity decreases from the alpine zone to the hill zone at lower altitude. Plants with numerous narrow vessels are mainly found in the alpine zone. Xylem without rays is mainly present in plants growing in the Alps, both at low and high altitudes. The reaction wood of the Brassicaceae consists primarily of thick-walled fibres, whereas that of the Resedaceae contains gelatinous fibres. The frequency of sclereids in Brassicaceae bark is an indicator of ecological differences: sclereids are rare in plants from the alpine zone and frequent in plants from all other ecotones.

Wood Anatomy of the Tribe Caesalpinieae (Leguminosae, Caesalpinioideae) in Venezuela

Abstract: We studied the microscopic wood anatomy of 8 genera and 30 species in the tribe Caesalpinieae, subfamily Caesalpinioideae, with a focus on the identification and comparative anatomy of these genera. Characters suitable for reliable identification include intervessel pit size, fibre wall thickness, septate fibres, storied structure, ray type, ray width, and silica bodies. A table of diagnostic characters, generic descriptions, and photomicrographs provide tools for identification and descriptive information for comparative and phylogenetic studies.

No Correlation between Latewood Formation and Leader Growth in Douglas-Fir Saplings

Abstract: SUMMARY The width of earlywood and latewood in conifer xylem may have a profound effect on water transport and storage, vulnerability to embolism, and wood strength, yet the controls over the timing of latewood formation are unclear. Tracheids differentiating in the cambial zone are influenced by IAA indole-3 acetic acid, the radial concentration gradient of which appears to either increase cell expansion (earlywood) or increase cell wall deposition (latewood). There are suggestive data that latewood begins to form when the growth of the leader stops, but defini tive results are lacking. Height growth was measured in 14 Douglas-fir (Pseudotsuga menziesii) saplings at 10 dates between May and August, from the beginning of the growing season until after height growth had ceased. The cambium was also pinned six times between June and July, to induce xylem scarring at known dates. After height growth ceased, saplings were harvested and transverse sections of the wood were made at the pin insertion points. The date at which 95% of the height growth had occurred and the date at which latewood formation had begun were estimated. Analysis showed no correlation of these data, suggesting that the two phenomena may occur around the same time, but that one is not causal of the other.

On the Origin of Intercellular Canals in the Secondary Xylem of Selected Meliaceae Species

Abstract: The anatomy, frequency, and origin of intercellular canals in the xylem of ten Meliaceae species (Carapa guianensis Aubl., Carapa procera DC., Cedrela odorata L., Cedrela fissilis Vell., Entandrophragma cilindricum Sprague, Entandrophragma utile Sprague, Khaya ivorensis A. Chev., Khaya senegalensis (Desr.) A. Juss., Swietenia macrophylla King, Swietenia mahagoni (L.) Jacq.) were investigated using 327 samples from institutional wood collections, 398 plantation grown trees, and 43 pot cultivated plants. Tangential bands of intercellular canals and single canals were found in the xylem of all ten species. Staining of microtome sections indicated that the chemical composition of the secretion is similar to that of “wound-gums”. Studying the origin of the intercellular canals along the stem axis, it became obvious that the formation of the canals can be induced by wounding of the primary meristems (in particular by insect attacks of Hypsipyla spp., wounding of root tips) and by wounding of the cambium (formation of 43–100% of the intercellular canals). In fast growing trees of Carapa spp., Entandrophragma utile, and Khaya ivorensis, planted at an experimental site near Manaus, Brazil, numerous canals were found which were not induced by wounding of the meristems. In these trees an out of phase sequence of xylem cell development and high growth stresses were observed, which are hypothesised to be a further trigger for the traumatic formation of intercellular canals.

Investigation of the relationships between anatomical pattern, density and local swelling of oak wood

Abstract: We coupled a digital X-ray imaging system with a humid air conditioner. This new configuration allows the shrinkage behaviour of thin samples to be measured. In order to control both the temperature and the relative humidity in the chamber, an air generator was developed which ensures very stable conditions even over several months. The X-ray beam passes through the chamber to the 2D detector. Twelve samples can be placed on a rotating sample holder. The strain field due to the moisture content variations is determined by an image correlation algorithm, which compares X-ray images collected at different moisture conditions. Moreover, inspection by X-ray simultaneously produces complementary data: the local density and the spatial organisation of the tissues within the anatomical pattern. Twelve oak samples, chosen for their wide variability of the anatomical pattern, were characterised using this device.Some models available in the literature are used to predict the swelling. fThe comparison between measurements and prediction is rather poor. The variable anatomical structure of the annual rings permits some explanations for this decrepancy and leads to the conclusion that the complete spatial organisation of the tissues has to be quantified to understand and to predict the behaviour of oak wood.

Epicormic Shoot Traces in the Secondary Xylem of the Triassic and Permian Fossil Conifer Species Woodworthia Arizonica — Short Communication

Abstract: Specimens of Woodworthia arizonica Jeffrey trees from the Late Triassic of Arizona, U.S.A. and the Permian of Brazil, typically have horizontal vascular traces that have extremely close contacts with the tracheids of the secondary xylem. In modern gymnospermous and angiospermous trees, such traces terminate on preventitious buds deeply embedded in their bark. Such buds develop into epicormic shoots, after substantial loss of foliage through fire or other damage.

High-Resolution Dendrochemical Analysis of Flood-Affected Oaks using Laser Ablation Icp-Mass Spectrometry

Abstract: Dendrochemical analysis was conducted on Quercus macrocarpa Michx. (bur oak) growing within the floodplain of the Red River, Canada, to determine if xylem formed during severe floods contained significantly perturbed chemistry. Wood samples were taken from five living trees in the same stand and from three timbers from a 19th-century building. Laser ablation ICP-mass spectrometry was used to determine the trace element chemistry in the earlywood and latewood of rings formed before, during and after major floods. Between-tree correlations were significant (p < 0.05) for Hg, Mg, Mn, Sr and Zn, suggesting that changes in the abundance of these elements over time might reflect common physiological processes or environmental signals. Mg, Mn and Sr concentrations were higher in the earlywood than in the latewood for both living and historical samples. These intra-annual shifts may reflect varying rates of uptake driven by seasonal changes in anatomical development, as well as stability of these elements after their initial deposition. Although no chemical anomalies are associated with 20th-century floods, earlywood coinciding with an extreme flood in 1826 contained low levels of Mg, Mn and Sr. These elemental anomalies might represent an independent biochemical flood signature but it is also possible they are a secondary expression of wood formation disrupted by flooding. In either case, elemental analysis does not provide any information beyond that obtained from studying anatomical features, and does not appear to be a viable tool to identify the occurrence of past floods.

Morphogenesis of the Specialized Peridermal Tissues in Decodon Allenbyensis from the Middle Eocene Princeton Chert

Abstract: Aquatic tissues in the submerged axes of Decodon allenbyensis Cevallos- Ferriz et Stockey are investigated and described in detail. Numerous well-preserved roots have primary aerenchymatous cortex and no secondary vascular tissues while other axes show transitions to secondary xylem and phloem, as well as periderm composed of thin-walled lacunate phellem. Phellem appears similar to the primary aerenchyma seen in aquatic roots of species of Ludwigia L.; however, similar lacunate tissue in extant Decodon verticillatus (L.) Ell. is secondary (phellem) and this study shows this tissue to be homologous to that seen in the fossil Decodon J.F. Gmel. A complex rhytidome is described in the largest fossil axes. It is composed of alternating bands of 'phelloids' and bands of non-active phloem with lacunae. This complex aquatic rhytidome is currently unknown in other living or fossil taxa.

Identification of Fibre Components in Packaging Grade Papers

Abstract: Environmental and economic issues have led to a significant increase of recycled paper as the main fibrous component of corrugated board the last years. Qualitative data on the different fibre types are needed for the evaluation of packaging fibre supply sources, which are becoming numerous and heterogeneous. Fifteen different packaging grade papers (7 linerboards and 8 corrugating medium) were selected to represent all the variety of papers available on the Spanish market. The origin of virgin and recycled fibres was identified by their morphological characteristics employing light microscopy and standard fibre analysis techniques. The waste-based papers (Waste based-liners and Fluting), Kraft-liners and Test-liner were highly variable containing 9–18 different wood and nonwood components. Semi-chemical, with 5–13 components, was the less variable grade. Hardwoods were identified as the most important fibre component from a quantitative standpoint. All papers contained in their hardwood mix Betula, Eucalyptus and Populus in significant amounts. Fagus sylvatica and Tilia were also frequently observed and in some papers were amongst major hardwood components. Prominent softwood components were found to be Pinus sylvestris, P. pinaster, P. radiata, Picea, Larix and in some papers Pinus nigra. The lower presence of a variety of softwood, hardwood and nonwood (mainly grasses) species and genera was due to the paper recycling process.

Cedreloxylon Cristalliferum, A New Record of Angiosperm Wood of Pliocene Age from Yunnan, China

Abstract: INTRODUCTIONThere are various reports of numerous fossil gymnosperm woods and occasional angio-sperm woods from the Mesozoic and Cenozoic sediments in China. So far, 24 species belonging to 21 genera and 14 families of Cenozoic angiosperm woods were described from Hubei, Shandong, Yunnan, Jiangsu, Shaanxi Provinces, and Beijing (Table 1). Here we report on Cedreloxylon cristalliferum, a new record of angiosperm wood of Pliocene age collected from the Earth Forest near Xinhua (25° 44.58' N, 101° 40.31' E) and Wanpu (25° 51.39' N, 101° 48.54' E) villages, Yuanmou Basin of Yunnan Prov-ince, SW China. The Yuanmou Basin of Yunnan, SW China is a famous site for discoveries of ho-minids and hominoids, and is filled with a thick series of Late Tertiary and Quaternary fluvio-lacustrine sediments, which have been covered by erosion into a badland topog-raphy where plant fossils are found. The Earth Forest in Yuanmou mainly consists of fluvio-lacustrine rocks aged from Pliocene to Pleistocene (Qian & Ling 1989). The sedi-ments of Wanpu Earth Forest containing sandstone and clay belong to the lower part of the Yuanmou Formation (Pu & Qian 1977), a Late Pliocene equivalent of the Sha-gou Formation (Zhang et al. 1994), while those of Xinhua Earth Forest consisting of lacustrine sandstone and clay are Pliocene in age (Qian & Ling 1989). The slides for cross, tangential and radial sections of wood samples were prepared by the standard methods of cutting, grinding and polishing using the different grades of carborundum powder (Lacey 1963). Both specimens and slides were deposited in the National Museum of Plant History, Institute of Botany, Chinese Academy of Sciences, Beijing, China. Anatomical terms used in this paper follow the recommendations of the IAWA list of Microscopic Features for Hardwood Identification (IAWA Committee 1989). Wood identification was based on Anatomy of the Dicotyledons (Metcalfe & Chalk 1950), Chinese woods (Cheng et al. 1992) and the ʻInside Woodʼ database (http://insidewood.lib.ncsu.edu/search/).

Wood anatomy of Craigia (Malvales) from southeastern Yunnan, China

Abstract: Wood anatomy of Craigia W.W. Sm. & W.E. Evans (Malvaceae s.l.), a tree endemic to China and Vietnam, is described in order to provide new characters for assessing its affinities relative to other malvalean genera. Craigia has very low-density wood, with abundant diffuse-in-aggregate axial parenchyma and tile cells of the Pterospermum type in the multiseriate rays. Although Craigia is distinct from Tilia by the presence of tile cells, they share the feature of helically thickened vessels – supportive of the sister group status suggested for these two genera by other morphological characters and preliminary molecular data. Although Craigia is well represented in the fossil record based on fruits, we were unable to locate fossil woods corresponding in anatomy to that of the extant genus.

Cretaceous Woods from the Farafra Oasis, Egypt

Abstract: There are fewer than 200 angiosperm wood records for the whole of the Cretaceous; the majority are from North America, Europe, and Asia. This paper describes two petrified woods from the Late Cretaceous Hefhuf Formation, Farafra Oasis, Egypt, a locality near the Campanian equator. Affinities of these two wood types cannot be determined with certainty. One wood has characteristics seen in the Lauraceae, Moraceae, and Anacardiaceae; the other wood has exclusively uniseriate homocellular rays, scalariform perforation plates, rare axial parenchyma, and alternate-opposite intervessel pitting.

Compression Wood does not Form in the Roots of Pinus Radiata

Abstract: We investigated the potential for the roots of Pinus radiata D. Don to form compression wood. Compression wood was not observed in either the tap or any lateral roots further than 300 mm from the base of the stem. This suggests that either the roots do not experience the stresses required to induce compression wood formation, or that they lack the ability to form it. Roots artificially subjected to mechanical stress also failed to develop compression wood. It is therefore unlikely that an absence of a compressive load on buried roots can account for the lack of compression wood. Application of auxin to the cambia of lateral roots was similarly ineffective at inducing the formation of compression wood. These observations suggest that the buried roots of radiata pine lack the ability to develop compression wood. We also report the formation of an atypical S3 wall layer in the mechanically-stressed and auxin-treated tracheids and suggest that a reaction wood that is different to compression wood may well form in roots.

Distribution of Libriform Fibers and Presence of Spiral Thickenings in Fifteen Species of Acer

Abstract: Fifteen Acer species were examined to study distribution and percentage by area of their libriform fibers. Safranin-O and astra blue dissolved in alcohol solution is an effective differential staining method to identify and localize libriform fibers. They have larger lumens than fiber tracheids, intercellular spaces, and occur in various patterns, ranging from large groups to wavy bands. In some cases they occur in radial files. The percentage by area of libriform fibers ranges from 14 to 40%. Inconspicuous to moderately visible spiral thickenings are part of the Acer libriform fibers and fiber tracheids. Differences in stain reactions and fluorescence indicate that libriform fibers differ in lignin concentration or composition from fiber tracheids – the concentration of syringyl lignin is greater in libriform fibers.