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Robert, Elisabeth M. R., Nele Schmitz, Paul Copini, Edo Gerkema, Frank J. Vergeldt, Carel W. Windt, Hans Beeckman, Nico Koedam, and Henk Van As. "Visualization of the stem water content of two genera with secondary phloem produced by successive cambia through Magnetic Resonance Imaging (MRI)." Journal of Plant Hydraulics 1 (October 6, 2014): e006. http://dx.doi.org/10.20870/jph.2014.e006.
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Shrubs and trees with secondary phloem tissue produced by successive cambia mainly occur in habitats characterized by a periodical or continuous lack of water availability. The amount of this secondary phloem tissue in stems of Avicennia trees rises with increasing soil water salinity and decreasing inundation frequency. Hence, increased water storage in secondary phloem tissue produced by successive cambia was put forward to be advantageous in harsh environmental conditions. It was however never tested whether the secondary phloem cells over the entire stem of woody species showing this wood anatomical feature are indeed water-filled as expected. In this preliminary and pioneering study, we use magnetic resonance imaging (MRI) to visualize the stem water content of three species with successive cambia, the mangroves Avicennia marina and A. officinalis and the non-mangrove Bougainvillea spectabilis. Measurements were conducted in living plants. We tested the hypothesis that not only the outermost phloem tissue has high water content but also the secondary phloem tissues over the entire stem from the bark inward to the pith, herewith serving as water storage sites. We can conclude that all secondary phloem tissue of both Bougainvillea and Avicennia has high water contents. This aligns with the contribution of secondary phloem tissue produced by successive cambia to ecological success in conditions of physiological drought. Further study should however be done to understand the mechanisms through which this secondary phloem tissue contributes to the water household of plants in conditions of water shortage.
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Sun, Yiming, Sha Ren, Shenglong Ye, Qiaoyan Tian, and Keming Luo. "Identification and Functional Characterization of PtoMYB055 Involved in the Regulation of the Lignin Biosynthesis Pathway in Populus tomentosa." International Journal of Molecular Sciences 21, no. 14 (July 9, 2020): 4857. http://dx.doi.org/10.3390/ijms21144857.
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Wood, which is mainly composed of lignified secondary cell wall, is the most abundant biomass in woody plants. Previous studies have revealed that R2R3-type MYB transcription factors are important regulators of the formation of the secondary cell wall in vascular plants. In this study, we isolated the R2R3-type MYB transcription factor gene PtoMYB055, which is mainly expressed in xylem and phloem tissue, from Populus tomentosa and demonstrate that PtoMYB055 is a key regulator of lignin biosynthesis. PtoMYB055 as a transcriptional activator is localized to the nucleus. Overexpression of PtoMYB055 upregulates expression of lignin biosynthetic genes in transgenic poplar plants, resulting in ectopic deposition of lignin in phloem tissue and an increase in thickness of the secondary cell wall. In sum, PtoMYB055 is a transcriptional activator that is involved in regulating lignin biosynthesis during the formation of the secondary cell wall in poplar.
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Petit, Giai, and Alan Crivellaro. "Comparative axial widening of phloem and xylem conduits in small woody plants." Trees 28, no. 3 (March 17, 2014): 915–21. http://dx.doi.org/10.1007/s00468-014-1006-1.
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Casey, Christine A., and Michael J. Raupp. "Effect of Supplemental Nitrogen Fertilization on the Movement and Injury of Azalea Lace Bug (Stephanitis pyrioides(Scott)) to Container-grown Azaleas." Journal of Environmental Horticulture 17, no. 2 (June 1, 1999): 95–98. http://dx.doi.org/10.24266/0738-2898-17.2.95.
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Abstract Certain arthropods feed selectively and perform better on plants and plant tissues with elevated levels of nitrogen. Yet it is a common practice to use supplemental nitrogen in the production and maintenance of woody landscape plants. The link between elevated nitrogen levels and improved performance of herbivorous arthropods is particularly strong for sap suckers in the order Heteroptera, the majority of which are phloem feeders. There have been no studies to date on the effects of fertilization of woody plants on important mesophyll-feeding Heteroptera, such as azalea lace bug. We examined the relationship between the movement and injury of azalea lace bug and levels of fertilization of azaleas. The objective of this study was to determine if this insect responded to supplemental nitrogen fertilization in a way similar to many phloem-feeding Heteroptera and mesophyll-feeding Acarina. In these taxa, numerous studies documented improved performance and increased host plant injury as a result of supplemental nitrogen fertilization. We measured injury and colonization by azalea lace bug of azaleas receiving four levels of nitrogen fertilization. Plants with elevated nitrogen levels were preferentially chosen by azalea lace bug but did not exhibit greater levels of leaf injury.
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Schweingruber, Fritz Hans. "Annual Growth Rings and Growth Zones in Woody Plants in Southern Australia." IAWA Journal 13, no. 4 (1992): 359–79. http://dx.doi.org/10.1163/22941932-90001290.
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Cross sections of 760 trunks of approximately 670 species from 47 families of shrubs, dwarf shrubs, and trees were examined to study the incidence and appearance of different categories of growth zones. In montane/alpine sites with relatively cool winter temperatures all the woody plants form distinct growth rings similar to those seen in boreal and temperate regions throughout the world, and thus these rings are considered to represent annual rings. Most species from this phytogeographical zone are useful for crossdating. In the savannahs, the jarrah and karri woodlands of the southwest and the subtropical rain forests of the southeast identifiable growth zones are formed in most species. The approximate age of the woods can be determined, but crossdating is difficult or impossible. In the desert areas woody plants form irregular growth zones, the number of which may correspond to the incidence of rainfall, and age determination and crossdating is mostly impossible. Members of the well-studied families Cupressaceae, Epacridaceae and Myrtaceae form growth zones that are more distinct than the Mimosaceae and Proteaceae. Included phloem is present in all Chenopodiaceae, one Loranthaceae and two species of Verbenaceae.
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Povilus, Rebecca A., Jeffrey M. DaCosta, Christopher Grassa, Prasad R. V. Satyaki, Morgan Moeglein, Johan Jaenisch, Zhenxiang Xi, et al. "Water lily (Nymphaea thermarum) genome reveals variable genomic signatures of ancient vascular cambium losses." Proceedings of the National Academy of Sciences 117, no. 15 (March 31, 2020): 8649–56. http://dx.doi.org/10.1073/pnas.1922873117.
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For more than 225 million y, all seed plants were woody trees, shrubs, or vines. Shortly after the origin of angiosperms ∼140 million y ago (MYA), the Nymphaeales (water lilies) became one of the first lineages to deviate from their ancestral, woody habit by losing the vascular cambium, the meristematic population of cells that produces secondary xylem (wood) and phloem. Many of the genes and gene families that regulate differentiation of secondary tissues also regulate the differentiation of primary xylem and phloem, which are produced by apical meristems and retained in nearly all seed plants. Here, we sequenced and assembled a draft genome of the water lily Nymphaea thermarum, an emerging system for the study of early flowering plant evolution, and compared it to genomes from other cambium-bearing and cambium-less lineages (e.g., monocots and Nelumbo). This revealed lineage-specific patterns of gene loss and divergence. Nymphaea is characterized by a significant contraction of the HD-ZIP III transcription factors, specifically loss of REVOLUTA, which influences cambial activity in other angiosperms. We also found the Nymphaea and monocot copies of cambium-associated CLE signaling peptides display unique substitutions at otherwise highly conserved amino acids. Nelumbo displays no obvious divergence in cambium-associated genes. The divergent genomic signatures of convergent loss of vascular cambium reveals that even pleiotropic genes can exhibit unique divergence patterns in association with independent events of trait loss. Our results shed light on the evolution of herbaceousness—one of the key biological innovations associated with the earliest phases of angiosperm evolution.
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Raven, J. A. "The physiology ofSalix." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 98 (1992): 49–62. http://dx.doi.org/10.1017/s0269727000007442.
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SynopsisSalixhas many physiological features in common with other deciduous woody plants, e.g. C3photosynthesis, occurrence of latitudinal photoperiodic ecotypes, and organic N (no) flux to the shoot in the xylem. Special points about the physiology ofSalixspp. which may have impact on their ecology and economic uses include: (i) relatively high (for woody plants) light-saturated rate of photosynthesis on a leaf area or leaf dry weight basis, (ii) sex differences in water (transpiration) costs of growth, (iii) very limited seed longevity and a wide range of temperature and light conditions permitting germination, and (iv) ready rooting and establishment of naturally or artificially detached twigs and branches. Areas in which work onSalixhas been especially influential for the development of plant physiology include: (i) the analysis of phloem functioning using aphids, (ii) the role of photoinhibition under natural conditions, and (iii) the realisation that the woody habit need not constrain the achieved activity of enzymes and hence N-based metabolic rates.
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Gao, Jing, Steve Arthurs, and Runqian Mao. "Asymmetric Interaction between Aphis spiraecola and Toxoptera citricida on Sweet Orange Induced by Pre-Infestation." Insects 11, no. 7 (July 3, 2020): 414. http://dx.doi.org/10.3390/insects11070414.
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Indirect interactions between herbivorous insects that share the same host have been focused on insects feeding on herbaceous plants, while few studies investigate similar interactions on woody plants. We investigated performance and feeding behavior of two citrus aphids, Aphis spiraecola Patch and Toxoptera citricida Kirkaldy, on sweet orange as affected by prior infestation of conspecifics and heterospecifics. Results showed that pre-infestation-induced interactions between A. spiraecola and T. citricida were asymmetric, with A. spiraecola gaining more fitness. In detail, pre-infestation by A. spiraecola decreased adult weight, enhanced survival rate and accelerated phloem sap acceptance of conspecifics. However, A. spiraecola pre-infestation did not affect performance or feeding behavior of T. citricida. In another infestation sequence, the pre-infestation of T. citricida did not affect conspecifics, but positively affected heterospecifics, indicated as a decreased pre-reproductive period, enhanced survival rate, adult weight, fecundity, and feeding efficiency, i.e., faster access and acceptance of phloem sap, and longer phloem sap ingestion duration. Furthermore, we found A. spiraecola pre-infestation enhanced amino acid concentration, amino acid to sugar ratio, activated salicylic acid and jasmonic acid marker gene expression, while T. citricida pre-infestation only depressed jasmonic acid marker gene expression. Changes in nutrient and phytohormone-dependent defense probably underlie the asymmetric effect.
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Verdaguer, Dolors, Pedro J. Casero, and Marisa Molinas. "Lateral root development in a woody plant, Quercus suber L. (cork oak)." Canadian Journal of Botany 78, no. 9 (September 1, 2000): 1125–35. http://dx.doi.org/10.1139/b00-077.
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The distribution and the ontogenesis of lateral roots have been investigated in the Mediterranean woody species Quercus suber L. (cork oak). Lateral roots arose in protoxylem-based ranks and a tendency to clumping was observed. Three stages are distinguished in lateral root primordium development. Lateral root primordia are derived mainly from pericycle cells. The endodermis contributed to the initial lateral root development, forming an endodermal cover that sloughs off with lateral root emergence. The unemerged lateral roots show an incipient layered root meristem; this meristem can be classified as a closed type meristem. Primary vascular connection takes place with the xylem strand opposite the lateral root primordium and the two adjacent phloem strands. Primary vascular connector elements are derived from pericyclic derivative cells. Vascular parenchyma cells contribute mainly in the development of the cambium and the subsequent secondary xylem and phloem connector elements. The secondary vascular elements of the lateral root and parent root differentiate in continuity. Vascular connection is discussed in relation to the root vascular plexus described in monocotyledonous and in some herbaceous dicotyledonous plants. An endodermis with suberized lamellae is continuous between the lateral and parent root in emerged lateral roots.Key words: lateral root, development pattern, apical lateral root meristem, root vascular connection, Quercus suber L.
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Lekhak, Manoj M., Amit D. Gondaliya, Shrirang R. Yadav, and Kishore S. Rajput. "Stem anatomy at various developmental stages of secondary growth in Turbina corymbosa (Convolvulaceae)." Plant Ecology and Evolution 151, no. 2 (August 22, 2018): 219–30. http://dx.doi.org/10.5091/plecevo.2018.1389.
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Background – Population growth of lianas in the tropical forest is credited to their ability of CO2 sequestration and efficiency of the narrow stems to supply water required for the amount of foliage it bears. Turbina corymbosa (L.) Raf. (Convolvulaceae Juss.) is one of the fast-growing invasive species of scrambling woody lianas. It covers trees entirely within a short period to compete with above-ground resources (particularly sunlight). However, no information is available on how it manages to cope up with an increasing demand of water supply and mineral nutrients. What are the structural and developmental patterns adapted by this species to expand the stem diameter for efficient supply of below-ground resources? Therefore, our aim was to investigate the secondary growth patterns and structure of secondary xylem and phloem in T. corymbosa.Methods – Several samples of the stem with various diameters were studied using a histological method. Morphological and anatomical analyses were carried out using light microscopy.Key results – With the initiation of secondary growth, stems lose their circular outline rapidly due to unequal deposition of secondary xylem and formation of successive cambia. New successive cambia initiate from parenchymatous cells as small crescent-shaped fragments on asymmetric/opposite sides and result in a different stem conformation. Though several segments of successive cambia are formed, very few stem samples form complete cambium rings. The secondary xylem formed by successive cambia is diffuse porous with indistinct growth rings and is composed of both wide and narrow (fibriform) vessels, tracheids, fibres, axial and ray parenchyma cells. The secondary phloem consists of sieve tube elements, companion cells, axial and ray parenchyma cells. In fully grown plants, cambial action (internal cambium) occurrs between the intraxylary phloem and protoxylem and produces secondary xylem and phloem near the pith region.Conclusion – Structural alterations and unequal deposition of conducting elements, occurrence of intraxylary phloem and flattening of the stem are suggested to facilitate rapid growth of the plants by providing required minerals and nutrients. Internal cambium formed at the periphery of the pith is bidirectional and produces secondary xylem externally and intraxylary phloem internally. Continued development of intraxylary phloem from the internal cambium provides an additional path for rapid and safe translocation of photosynthates.
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Tonfack, Libert B., Steven G. Hussey, Adri Veale, Alexander A. Myburg, and Eshchar Mizrachi. "Analysis of Orthologous SECONDARY WALL-ASSOCIATED NAC DOMAIN1 (SND1) Promotor Activity in Herbaceous and Woody Angiosperms." International Journal of Molecular Sciences 20, no. 18 (September 18, 2019): 4623. http://dx.doi.org/10.3390/ijms20184623.
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SECONDARY WALL-ASSOCIATED NAC DOMAIN1 (SND1) is a master regulator of fibre secondary wall deposition in Arabidopsis thaliana (Arabidopsis), with homologs in other angiosperms and gymnosperms. However, it is poorly understood to what extent the fibre-specific regulation of the SND1 promoter, and that of its orthologs, is conserved between diverged herbaceous and woody lineages. We performed a reciprocal reporter gene analysis of orthologous SND1 promoters from Arabidopsis (AthSND1), Eucalyptus grandis (EgrNAC61) and Populus alba × P. grandidentata (PagWND1A) relative to secondary cell wall-specific Cellulose Synthase4 (CesA4) and CesA7 promoters, in both a non-woody (Arabidopsis) and a woody (poplar) system. β-glucuronidase (GUS) reporter analysis in Arabidopsis showed that the SND1 promoter was active in vascular tissues as previously reported and showed interfascicular and xylary fibre-specific expression in inflorescence stems, while reporter constructs of the woody plant-derived promoters were partial to the (pro)cambium-phloem and protoxylem. In transgenic P. tremula × P. alba plants, all three orthologous SND1 promoters expressed the GUS reporter similarly and preferentially in developing secondary xylem, ray parenchyma and cork cambium. Ours is the first study to reciprocally test orthologous SND1 promoter specificity in herbaceous and woody species, revealing diverged regulatory functions in the herbaceous system.
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Iusypiva, Tetiana, and Galyna Miasoid. "The Impact of Industrial Pollution with Toxic Gases on Stem Histological Parameters of Woody Plant Undergrowth under Conditions of the Southern Industrial Zone of the City of Dnipro, Ukraine." International Letters of Natural Sciences 59 (October 2016): 62–71. http://dx.doi.org/10.18052/www.scipress.com/ilns.59.62.
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The paper examines the influence of industrial emissions of sulphur (IV) and nitrogen (IV) oxides on stem histological parameters of the autochthonous woody plant species undergrowth ofAcer platanoidesL. andFraxinus excelsiorL., which are natural forest edificators in the steppe zone of Ukraine. It shows that stem anatomical characteristics undergo quantitative changes in the annual undergrowth shoots of the two tree species under anthropogenic burden, with the most significant changes in the area of heavy pollution. Results indicate the decrease of such stem parameters as stem and stele diameters, wood radius and primary cortex thickness under high concentrations of SO2and NO2in seedlings of both species. However, this parameter drops inA. platanoidesstems by reducing the collenchyme width, whereas it reduces inF. excelsiorstems due to cork thickness loss. Another difference in the response ofA. platanoidesto the influence of phytotoxic pollutants compared toF. excelsioris the depletion of conducting elements of its phloem, which results in thinning the stem secondary cortex. The research findings prove high vulnerability ofA. platanoidesundergrowth to the chronic SO2and NO2exposure. Therefore, this woody species is suggested to be used as a test object in monitoring research on plants of virginal group in the technogenic areas contaminated with sulphur (IV) and nitrogen (IV) oxides.
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Liesche, Johannes, Marcelo R. Pace, Qiyu Xu, Yongqing Li, and Shaolin Chen. "Height-related scaling of phloem anatomy and the evolution of sieve element end wall types in woody plants." New Phytologist 214, no. 1 (December 9, 2016): 245–56. http://dx.doi.org/10.1111/nph.14360.
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Helfter, C., J. D. Shephard, J. Martinez-Vilalta, M. Mencuccini, and D. P. Hand. "A noninvasive optical system for the measurement of xylem and phloem sap flow in woody plants of small stem size." Tree Physiology 27, no. 2 (February 1, 2007): 169–79. http://dx.doi.org/10.1093/treephys/27.2.169.
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Bachelier, Julien B., Imran Razik, Maria Schauer, and James L. Seago. "Roots Structure and Development of Austrobaileya scandens (Austrobaileyaceae) and Implications for Their Evolution in Angiosperms." Plants 9, no. 1 (January 1, 2020): 54. http://dx.doi.org/10.3390/plants9010054.
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Since the resolution of the ANA grade [Amborellales, Nymphaeales, Austrobaileyales] as sister to all other flowering plants, a few comparative studies of root structure have suggested that some of their anatomical traits could be of importance to understanding root evolutionary development and angiosperm phylogeny. However, there is still a paucity of information on root structure and apical meristems (RAMs) in these lineages and especially the sister to all other Austrobaileyales, Austrobaileya scandens. We used microtome sections and bright field, epifluorescence, laser confocal, and scanning electron microscopy to study adventitious root RAMs and tissues of A. scandens. Our results indicate that root structure is relatively simple in A. scandens. The epidermis has a thick cuticle and lacks root hairs. The stele is typically diarch, or some modification thereof, and surrounded by a cortex differentiated into a uniseriate endodermis, a middle region sometimes packed with starch, some oil cells, and colonized by arbuscular mycorrhizal fungi, and a multiseriate exodermis. Secondary growth produced many vessel elements in the secondary xylem and scattered sclerenchymatous fibers in secondary phloem. The absence of distinct patterning within the RAM and between the RAM and derivative differentiating tissues shows that the RAM is open and characterized by common initials. Roots structure and anatomy of A. scandens are thus essentially similar to some previously described in Amborella or Illicium in the ANA grade and many magnoliids, and suggest that the first woody flowering plants likely had an open RAM with common initials. Their functional and evolutionary significance in woody early-diverging and basal lineages of flowering plants and gymnosperms remains unclear, but they are clearly ancestral traits.
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Yamamoto, F., T. T. Kozlowski, and K. E. Wolter. "Effect of flooding on growth, stem anatomy, and ethylene production of Pinushalepensis seedlings." Canadian Journal of Forest Research 17, no. 1 (January 1, 1987): 69–79. http://dx.doi.org/10.1139/x87-013.
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Flooding of soil for 43 days greatly altered growth and stem anatomy and increased ethylene production by stems of 10-month-old Pinushalepensis seedlings. Flooding reduced the dry weight increment of seedlings primarily as a result of decay of roots and, to a lesser extent, inhibition of growth of roots and needles. Flooding did not influence height growth of seedlings but increased stem diameter, largely because of an increase in bark thickness at all stem heights and stem hypertrophy associated with proliferation of phloem parenchyma cells and an increased amount of intercellular space in the phloem. The effects of flooding on xylem increment varied appreciably with stem height. In the submerged portion of the stem, flooding greatly reduced the number of tracheids laid down per radial file. Flooding also slightly reduced the number of tracheids produced in the portion of the stem just above the water level. In the upper stem, however, flooding had little effect on xylem increment and on tracheid production for the first 29 days but increased both thereafter. Flooding also induced formation of short, thick-walled, rounded tracheids resembling those in compression wood. However, these tracheids developed an S3 wall layer, which is absent in well-developed compression wood. Flooding also increased the number of longitudinal resin ducts as well as the number and size of the xylem rays. The basic density of stem segments was lower in flooded than in unflooded seedlings, largely because of the high proportion of parenchyma cells and more intercellular spaces in the wood and bark of flooded seedlings. Flooding greatly increased production of 1-amino-cyclopropane-1-carboxylic acid by roots and ethylene by stems. The capacity for production of ethylene increased faster in stem segments just above the water line than in submerged portions of stems. However, the capacity for ethylene production as a flooding response declined progressively with increase in stem height above the basal whorl of branches. The data indicated an important regulatory role of ethylene in altering growth and stem anatomy of woody plants.
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Pellett, Norman E., and David A. Heleba. "Comparing Callus Growth with Discoloration and Electrical Conductivity as Measures of Stem Injury after Freezing Woody Plants." Journal of the American Society for Horticultural Science 123, no. 5 (September 1998): 826–31. http://dx.doi.org/10.21273/jashs.123.5.826.
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Most of 36 crabapple and 19 other woody plant taxa demonstrated the ability, when dormant, to grow a continuous row of callus along the cambial region on split-stem pieces within 5 to 7 days of incubation at 25 °C. The ability to grow callus after freezing tests was compared with discoloration and electrical conductivity for determining laboratory freeze injury to selected taxa. Hardiness levels were determined using the procedures of callus growth, discoloration, and electrical conductivity after freezing stem pieces of Jack crabapple [Malus baccata (L.) Borkh. `Jacki'], pink bud Sargent crabapple [M. sargentii Rehd. `Rosea'], Mary Potter crabapple [Malus sp. `Mary Potter'], and snowberry mountainash [Sorbus discolor (Maxim.) Maxim.]. Sampling dates for laboratory freezing tests were chosen to represent midwinter cold hardiness and partial hardiness of either late fall or early spring. There was a high correlation between discoloration and callus ratings for most plants; however, the two methods usually did not identify the same critical temperature (T50) for injury. The critical temperatures identified by callus growth was often 3 to 6 °C lower than for discoloration. For many taxa, callus growth was easier to see than discoloration of cambium and phloem, providing a less subjective evaluation of injury. TTC (2,3,5-triphenyl tetrazolium chloride) treatment was sometimes useful to identify callus growth that died after forming. The critical temperature (Tc), the highest temperature at which relative electrical conductivity differed significantly from the control temperature, was higher in most cases, indicating less cold hardiness than the T50 for callus and discoloration. The callus procedure may have value for evaluating injury to the cambial zone from freezing and other plant stresses because it determines the ability of the plant to continue growth.
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Mussina, Aitzhamal S., Gaukhar U. Baitasheva, Meruyert S. Kurmanbayeva, Galia J. Medeuova, Adilhan A. Mauy, Elmira M. Imanova, Akbota Zh Kurasbaeva, Zaida S. Rachimova, Yerlan S. Nurkeyev, and Kanat Orazbayev. "Anatomical and morphological changes of the juniper under the influence of heavy metals in condition of man-induced load." Israel Journal of Ecology and Evolution 64, no. 1-4 (November 10, 2018): 35–43. http://dx.doi.org/10.1163/22244662-06303005.
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Reaction of the plant body in polluted conditions allows estimating the anthropogenic impact on the environment. The aim of this work is to study anatomical and morphological changes of juniper in terms of the polymetallic pollution of the environment and under the influence of heavy metals. The assessment of some heavy metals impact on juniper was conducted after the planting of seed samples in the soil and obtaining good germination. The juniper has been treated with heavy metal solutions in the lab for 4 months. To determine the anatomical structures of the leaves of the juniper, the samples were fixed by the Strasburger-Fleming method. Under the influence of urban air, negative anatomical and morphological changes of juniper were discovered, the significant increase in the thickness of the needles, the thickness of the conducting bundle and the thickness of the epidermis was noted, that, apparently, provides higher resistance to man-induced pollution. It is shown that the process of environmental restoration can be done due to self-purification by using adsorption properties of leaves of woody plants, for example juniper, that is able to absorb heavy metals (lead, cadmium, cobalt, chromium, nickel, zinc and copper) from urban air. It was first discovered that the effects of heavy metals (lead and nickel) as the nutrient medium leads to the significant changes of the leaves’ anatomical structure (the swelling of the phloem, some decondensation in the mesophyll). The research results allow recommending the juniper for phytoremediation, bioindication and landscape gardening of cities and settlements in different countries.
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Voglmayr, H., M. B. Aguirre-Hudson, H. G. Wagner, S. Tello, and W. M. Jaklitsch. "Lichens or endophytes? The enigmatic genus Leptosillia in the Leptosilliaceae fam. nov. (Xylariales), and Furfurella gen. nov. (Delonicicolaceae)." Persoonia - Molecular Phylogeny and Evolution of Fungi 42, no. 1 (July 19, 2019): 228–60. http://dx.doi.org/10.3767/persoonia.2019.42.09.
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Based on DNA sequence data, the genus Leptosillia is shown to belong to the Xylariales. Molecular phylogenetic analyses of ITS-LSU rDNA sequence data and of a combined matrix of SSU-ITS-LSU rDNA, rpb1, rpb2, tef1 and tub2 reveal that the genera Cresporhaphis and Liberomyces are congeneric with Leptosillia. Coelosphaeria fusariospora, Leptorhaphis acerina, Leptorhaphis quercus f. macrospora, Leptorhaphis pinicola, Leptorhaphis wienkampii, Liberomyces pistaciae, Sphaeria muelleri and Zignoëlla slaptonensis are combined in Leptosillia, and all of these taxa except for C. fusariospora, L. pinicola and L. pistaciae are epitypified. Coelosphaeria fusariospora and Cresporhaphis rhoina are lectotypified. Liberomyces macrosporus and L. saliciphilus, which were isolated as phloem and sapwood endophytes, are shown to be synonyms of Leptosillia macrospora and L. wienkampii, respectively. All species formerly placed in Cresporhaphis that are now transferred to Leptosillia are revealed to be non-lichenized. Based on morphology and ecology, Cresporhaphis chibaensis is synonymised with Rhaphidicyrtis trichosporella, and C. rhoina is considered to be unrelated to the genus Leptosillia, but its generic affinities cannot be resolved in lack of DNA sequence data. Phylogenetic analyses place Leptosillia as sister taxon to Delonicicolaceae, and based on morphological and ecological differences, the new family Leptosilliaceae is established. Furfurella, a new genus with the three new species, F. luteostiolata, F. nigrescens and F. stromatica, growing on dead branches of mediterranean fabaceous shrubs from tribe Genisteae, is revealed to be the closest relative of Delonicicola in the family Delonicicolaceae, which is emended. ITS rDNA sequence data retrieved from GenBank demonstrate that the Leptosilliaceae were frequently isolated or sequenced as endophytes from temperate to tropical regions, and show that the genus Leptosillia represents a widely distributed component of endophyte communities of woody plants.
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Lv, Gengxin, Jun Qing, Hongyan Du, Qingxin Du, Yide Meng, Feng He, Panfeng Liu, Lanying Du, and Lu Wang. "Comparing Rooting Ability and Physiological Changes of Two Eucommia ulmoides Improved Varieties." Forests 12, no. 9 (September 17, 2021): 1267. http://dx.doi.org/10.3390/f12091267.
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Eucommia ulmoides (E. ulmoides) is a significant national strategic resource in China. It is a natural high quality rubber resource, with great development potential. We found large differences in rooting ability during adventitious root (AR) formation in two E. ulmoides improved varieties. Therefore, we used two improved varieties of E. ulmoides, ‘Huazhong 6’ (H6, with rooting rate 85.3%) and ‘Huazhong 8’ (H8, with rooting rate 22.5%) to explore the cutting rooting mechanism. In this study, we mainly determined the morphological development process of E. ulmoides cutting rooting, and compared the rooting-related indexes of the two improved varieties, and the changes in physiological indexes closely related to rooting, which include endogenous hormones, oxidases and nutrients in the phloem of the basal stem. The results showed that indole–3–acetic acid (IAA), zeatin riboside (ZR), IAA/ZR and indoleacetic acid oxidase (IAAO) were the key factors that caused big differences in rooting ability between the two E. ulmoides improved varieties. The increase in endogenous hormone IAA content and IAA/ZR value were necessary for the formation of AR. The increase in IAA content was beneficial to AR formation. The activity of IAAO was significantly negatively correlated with the rooting ability of the E. ulmoides cuttings. The high IAAO activity of the H8 cuttings led to the consumption of IAA. Although the content of IAA increased, the rooting conditions were not reached. The accumulation of nutrients before rooting also has an important effect on rooting; it is easy for cuttings to root when the carbon–nitrogen ratio (C/N) value is high. This research provides an improved understanding of the cellular and physiological underpinnings of the AR process in woody plants. In addition, it provides a theoretical basis and foundation for subsequent research on E. ulmoides cuttage technology.
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Nair, M. N. B. "Structure of Stem and Cambial Variant in Spatholobus Roxburgii (Leguminosae)." IAWA Journal 14, no. 2 (1993): 191–204. http://dx.doi.org/10.1163/22941932-90001317.
Full textAbstract:
The stern of Spatholobus roxburghii, a tropicalliana, has alternating layers of xylem and phloem as a result of formation and activity of successive cambia. Successive cambial rings are developed by dedifferentiation of groups of parenchyma cells outside the discontinuous band of sclereid-fibres. The sclereid- fibre band is formed by the development of sclereids between the primary bark fibres. Each successive cambium first produces a layer of sclereid-fibres which separates the vascular tissue produced by one cambial ring from the other. After secondary growth, the epidermis is replaced by periderm. In the older stern phelloderm contributes to the formation of new cambiallayers. Secondary phloem has sieve tube members; companion cells, phloem parenchyma, phloem fibres and secretory cells. The wood shows a tendency towards ring-porosity only in the first xylem layer. The subsequent layers are diffuseporous. The vessels are wide and narrow. Perforated ray cells or radial vessels are frequent in the wood and probably help in vertical conduction by interconnecting vessel endings. In this scandent species parenchyma cells are abundant. It is inferred that they help the vessel segments to remain undamaged when the woody stern twists around supports.
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Luongo, L., A. Haegi, M. Galli, S. Berti, S. Vitale, and A. Belisario. "First Report of Phytophthora megasperma Causing Decline and Death on Celtis australis in Italy." Plant Disease 99, no. 1 (January 2015): 155. http://dx.doi.org/10.1094/pdis-05-14-0534-pdn.
Full textAbstract:
European hackberry (Celtis australis L.) is a popular shade tree mainly planted in southern Europe and known to be tolerant to dry and poor soils. In early autumn 2013, hackberry plants grown in soil in a commercial nursery located in the floodplain in Umbria region showed symptoms of wilting, dieback, and death. Up to 100% of the canopy was affected, and over 60% of the plants were symptomatic or dead. A Phytophthora species was consistently isolated from symptomatic 6-year-old plants by plating small pieces of collar and root tissues, cut from the margin of dark-brown necrotic lesions, onto P5ARPH selective medium (4). Pure cultures were obtained by single-hyphal transfers on potato dextrose agar (PDA). Sporangia, produced on pepper seeds in soil extract solution (3), were nonpapillate and noncaducous, measuring 34.0 to 85.0 × 22.0 to 50.0 μm. Oospores had an average diameter of 44 μm with mostly paragynous antheridia. On the basis of morphological features, the isolates were identified as P. megasperma Drech. (2). The identity was confirmed by sequencing the cytochrome c oxidase subunit II (Cox II) (5), which gave 100% identity with P. megasperma sequences available in GenBank (GU222070), and by sequencing the internal transcribed spacer (ITS) using the universal primers ITS4 and ITS6, which gave 99% identity with the AF266794 sequence from Cooke et al. (1). The sequences of one isolate (AB239) were deposited in the European Nucleotide Archive (ENA) with accession numbers HG973451 and HG973450 for Cox II and ITS, respectively. Pathogenicity tests were conducted in the greenhouse with isolate AB239 on eight 2-year-old potted European hackberry plants. Mycelial plugs (5 mm diameter) cut from the margins of actively growing 8-day-old cultures on PDA were inserted through the epidermis to the phloem at the collar level. Two plants were used as controls and treated as described above except that sterile PDA plugs replaced the inoculum. Inoculated plants were kept for 4 weeks in a greenhouse at 24 ± 2°C. During that period, inoculated plants showed wilting symptoms similar to those observed in the field. Lesions were evident at all the inoculation points progressing downward to the roots. Colonies of Phytophthora were isolated from the margins of lesions and identified as P. megasperma, thus fulfilling Koch's postulates. Controls remained symptomless. P. megasperma taxonomy is rather complex since it embraces different subgroups, including host specialized forms (formae speciales), some of which are recognized as biological species. Based on morphological and molecular data presented here, the Phytophthora isolates from hackberry belong to P. megasperma sensu stricto, which is included in the “pathogenic to a broad range of hosts” (BHR) group (1). This pathogen is rather polyphagous, attacking mainly fruit and ornamental woody plants, commonly Prunus spp., Malus spp., and Actinidia deliciosa. Like other homothallic Phytophthora species, it is particularly dangerous due to its abundant production of thick-walled resting oospores that enable long-term survival in the soil. To our knowledge this is the first report of P. megasperma sensu stricto (1) on C. australis and its family Ulmaceae/Cannabaceae. References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) D. C. Erwin and O. K. Ribeiro, American Phytopathological Society, St. Paul, MN, 1996. (3) E. Ilieva et al. Eur. J. Plant Path. 101:623, 1995. (4) S. N. Jeffers and S. B. Martin. Plant Dis. 70:1038, 1986. (5) F. N. Martin and P. W. Tooley. Mycologia 95:269, 2003.
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Mirabolfathy, M., J. Z. Groenewald, and P. W. Crous. "The Occurrence of Charcoal Disease Caused by Biscogniauxia mediterranea on Chestnut-Leaved Oak (Quercus castaneifolia) in the Golestan Forests of Iran." Plant Disease 95, no. 7 (July 2011): 876. http://dx.doi.org/10.1094/pdis-03-11-0153.
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The chestnut-leaved oak (Quercus castaneifolia) is native to the Alborz Mountains, including the Golestan Forests, in northern Iran. Trees grow up to 35 (-50) m tall with a trunk up to 2.5 (-3.5) m in diameter. During 2010, we received reports of a decline of oak trees in the Ghorogh Region of the Golestan Forests. The decline began with discolorations and browning of the leaves, resulting in drying of the foliage. Viscous liquid exudates were observed on the trunks, resulting in a brown-black discoloration of phloem and bark. In January 2011, all infected trees were dead and exhibited symptoms of charcoal disease with carbonaceous, perithecial stromata erupting from the bark on stems. Perithecia were obovoid, containing short-stipitate, amyloid asci with dark brown, ellipsoid ascospores, 14 to 19 × 7 to 9 μm, with straight germ slits along the spore length. On the basis of these morphological characteristics, the fungus was identified as Biscogniauxia mediterranea. Blast searches of the NCBI GenBank nucleotide database were done using ITS sequences derived from three cultures (CBS 129072 to 129074). GenBank Accession Nos. JF295127 to JF295129 of the isolated fungus differed by one nucleotide from B. mediterranea (GenBank Accession No. AF280624) (1,3). Pathogenicity tests were conducted using an isolate of B. mediterranea under greenhouse conditions. Six-month-old Q. castaneifolia seedlings were inoculated by means of stem wounds with a mycelial plug of colonized potato dextrose agar. After 6 months, typical decline disease symptoms associated with charcoal disease were observed and the same fungus was reisolated. Perithecia were observed on the surface of black carbonaceous stromata, which usually developed on stems of inoculated plants. The decline is known as charcoal disease because fungal growth induces a typical charcoal-black surface on diseased branches and trunks. The pathogen can easily spread through large cavity vessels, colonize bark and woody tissues, and is able to kill the host in a single, growing season. B. mediterranea causes necrosis on stems and branches of Quercus spp., including Q. suber, Q. cerris, Q. frainetto, Q. pubescens (4), Q. alba, Q. ilex, Q. imbricaria, Q. lusitanica, Q. palustris, and Q. pyrenaica (2) in Europe, North America, Africa, New Zealand, and Asia (China and India). On the basis of our current knowledge, Q. castaneifolia represents a new host of B. mediterranea, and this is the first report of this fungal pathogen from Iran causing charcoal disease on Q. castaneifolia trees in the Golestan Forest. Given its new introduction into Iran, it is highly likely that it will spread to species of Fagus, Zelkova, and other woody hosts in the area. References: (1) J. Collado et al. Mycologia 93:875, 2001. (2) D. L. Hawksworth. No. 359. Description of Pathogenic Fungi and Bacteria. CMI, Kew, UK, 1972. (3) A. Mazzaglia et al. Mycol. Res. 105:952, 2001. (4) A. Vannini and G. Scarascia Mugnozza. Eur. J. For. Pathol. 21:193, 1991.
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Nair, M. N. B., and H. Y. Mohan Ram. "Structure of Wood and Cambial Variant in the Stem of Dalbergia Paniculata Roxb." IAWA Journal 11, no. 4 (1990): 379–91. http://dx.doi.org/10.1163/22941932-90000526.
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The wood of Dalbergia paniculata is unique as it consists of concentric layers of broad xylem, alternating with bands of narrow phloem. This anomaly results from the periodic formation of successive cambia in the secondary phloem. Some phloem parenchyma cells dedifferentiate to form a discontinuous ring of cambium. Such parenchyma cells have higher succinate dehydrogenase activity than the neighbouring cells of secondary phloem. The newly differentiated cambial layer functions bidirectionally, and its products give rise to xylem internally and phloem externally. The phloem along with cambium present internal to the newly formed xylem becomes included.The wood is diffuse-porous and the intervessel pits are vestured. The phloem has welldifferentiated sieve tube members and companion cells.
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Cevallos-Ferriz, Sergio R. S., and Ruth A. Stockey. "Vegetative remains of the Magnoliaceae from the Princeton chert (Middle Eocene) of British Columbia." Canadian Journal of Botany 68, no. 6 (June 1, 1990): 1327–39. http://dx.doi.org/10.1139/b90-169.
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One wood block and many small twigs (up to 1.3 cm diam.) with little secondary growth and showing magnoliaceous characters were identified from the Princeton chert locality (Middle Eocene) of British Columbia, Canada. Specimens were studied with a modified cellulose acetate peel technique and hydrofluoric acid. Well-preserved primary tissues include a chambered pith that distinguishes these twigs from other woods in the chert. Secondary xylem has solitary vessels, radial multiples, and clusters, scalariform perforation plates with 8–27 bars, scalariform, transitional, and opposite intervascular pitting, and tyloses. Imperforate tracheary elements with circular bordered pits, heterocellular and homocellular rays, and marginal parenchyma characterize the twigs. Secondary phloem has dilated rays, alternating bands of fibers and thin-walled cells, and sclerified ray and axial cells. In older wood, opposite intervascular pitting and homocellular rays, suggest affinities with Liriodendron L.; however, the presence of opposite, scalariform, and transitional intervascular pitting and secondary phloem structure necessitate its inclusion in Liriodendroxylon Prakash et al. Liriodendroxylon princetonensis Cevallos-Ferriz et Stockey sp.nov. is distinguished from other species in this genus by the presence of homocellular rays, scalariform intervascular pitting, and well-preserved extraxylary tissues that are unknown for the other fossil species. Liriodendroxylon princetonensis adds to the diversity of extinct magnoliaceous plants during the Eocene and represents the oldest known species of this genus. These plants were probably part of the surrounding forest vegetation in the Princeton basin. Like most extant Magnoliales, L. princetonensis probably lived under subtropical to warm-temperate, moist conditions. Key words: Magnoliaceae, Liriodendroxylon, fossil woods, Eocene.
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den Outer, R. W. "Storied Structure of the Secondary Phloem." IAWA Journal 7, no. 1 (1986): 47–51. http://dx.doi.org/10.1163/22941932-90000438.
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The anatomy of the secondary phloem with a storied structure of 49 species of woody dicotyledons from the Ivory Coast, West Africa, has been studied. They belong to the families Bixaceae (1 species), Bombacaceae (3 species), Caesalpiniaceae (4 species), Papilionaceae (18 species), Sterculiaceae (16 species), and Tiliaceae (7 species). In the Bixaceae and Sterculiaceae only the axial system is storied whereas in the four other families usually both the ray and axial systems are storied.
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Millay, Michael A., Thomas N. Taylor, and Edith L. Taylor. "Phi Thickenings in Fossil Seed Plants from Antarctica." IAWA Journal 8, no. 3 (1987): 191–201. http://dx.doi.org/10.1163/22941932-90001046.
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Primary anatomy and secondary development is described for two root types from the Fremouw Peak locality (Transantarctic Mts, Antarctica) of early to middle Triassic age. Roots of Antarcticycas have a bilayered cortex with thick surface cuticle, diarch xylem, and a clearIy defined endodermis surrounded by a single cell layer possessing phi thickenings. Secondary development begins with phellern and phelloderm production from the out er primary phloem position, and is followed bya bifacial vascular cambium next to the primary xylem that pro duces sieve cells and ray parenchyma to the outside. Young roots of Antarcticoxylon are similar to those of Antarcticycas, but may possess 2-3 cell layers with phi thickenings. Secondary development from a bifacial vascular cambium produces alternating bands of sieve cells and phloem parenchyma cells in the secondary phloem and wood with uniseriate rays and scattered axial parenchyma. The presence of phi thickenings and an epidermal cutieie in both roots suggests environmental stress related to water regulation. The occurrence of phi thickenings in the roots of some conifers, angiosperms, a fossil cycad and a probable seed fern suggests this character is of ecological rather than phylogenetic significance.
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Salleo, Sebastiano, Patrizia Trifilò, Sara Esposito, Andrea Nardini, and Maria A. Lo Gullo. "Starch-to-sugar conversion in wood parenchyma of field-growing Laurus nobilis plants: a component of the signal pathway for embolism repair?" Functional Plant Biology 36, no. 9 (2009): 815. http://dx.doi.org/10.1071/fp09103.
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The ability of stems of Laurus nobilis (L.) to refill embolised xylem conduits was studied in plants both at optimal water supply (W) and under conditions of soil drought inducing xylem pressures (Px) of –1.54 (S1) and –2.35 MPa (S2). Starch depolymerisation in wood parenchyma was measured as percentage of cells ‘with high starch content’ (HSC-cells) counted under a microscope. HSC-cells decreased during embolism and increased again in refilled stems. A direct relationship was found between percentage of HSC-cells and Px, with HSC-cells between 65 and 75% of the total at Px ≥ –0.6 MPa, at which recovery from PLC was recorded. At low transpiration, starch re-appeared in wood parenchyma cells but only in plants that showed diurnal stomatal opening (W- and S1-plants). In S2-plants showing diurnal stomatal closure and nocturnal opening with Px between –1.2 to –2.4 MPa, HSC-cells were only 25% and plants did not recover from PLC. This finding suggests that (i) the Px threshold for embolism repair was ≥ –0.6 MPa, and (ii) impeded phloem loading limits starch content in wood parenchyma and embolism repair. We conclude that starch depolymerisation acts as a signal to phloem unloading sugars to embolised conduits thus generating the necessary osmotic gradients driving refilling.
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Hayden, Sheila M., and W. John Hayden. "Stem Development, Medullary Bundles, and Wood Anatomy of Croton Glandulosus Var. Septentrionalis (Euphorbiaceae)." IAWA Journal 15, no. 1 (1994): 51–63. http://dx.doi.org/10.1163/22941932-90001342.
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Anatomy and development of vascular tissues in the annual stems of Croton glandulosus var. septentrionalis are described. In primary stages of growth the stem possesses a eustele of bicollateral bundles; internal phloem is notably more extensive than the external. In addition to a vascular cambium and secondary xylem that form in the usual fashion, additional cambia add cells to the internal phloem portion of the bicollateral bundles, forming well-marked medullary bundles at the perimeter of the pith. At first, the perimedullary cambial strands produce only internal secondary phloem; later, internal secondary xylem is also formed in some stems. When internal secondary xylem is present, the medullary bundles have an inverted orientation, i.e., phloem innermost (towards centre of pith) and xylem outermost (near protoxylem). Cells of the medullary bundles include sieve tube elements, vessel ekments, and fibres. Normal (external) secondary phloem is weakly developed. Normal secondary xylem contains short vessel elements with simple perforation plates and alternate intervascular pits, libriform fibres, narrow heterocellular rays, and lacks axial parenchyma.
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Thomas, K. I., and R. E. Wall. "Stem pitting and annual ring discoloration in yellow birch." Canadian Journal of Botany 64, no. 9 (September 1, 1986): 2165–67. http://dx.doi.org/10.1139/b86-286.
Full textAbstract:
The stem tissues of yellow birch (Betula alleghaniensis Britton) saplings, with wavy bands of stained xylem parallel to the annual rings and depressions in the xylem at the xylem–phloem interface (stem pitting), were studied microscopically. The bands of stained xylem consisted of abnormally formed parenchyma (parenchymatous wood) interspersed with collapsed cells. Rays in the affected areas showed increases in both cell numbers and cell size, often being indistinguishable from adjacent parenchymatous wood. Aggregate rays were associated with stained bands as well as with stem pitting in the xylem and corresponding protrusions of the phloem.
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Furuno, Takeshi. "Bark Structure of Deciduous Broad-Leaved Trees Grown in the San'in Region, Japan." IAWA Journal 11, no. 3 (1990): 239–54. http://dx.doi.org/10.1163/22941932-90001181.
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The bark anatomy of 55 deciduous broadleaved tree species from the San'in Region is described. Anatomical features of ray and axial parenchyma cells, phloem fibres, and sclereids are tabulated. Individual species have their own characteristic bark structure. The diversity in tissue arrangement in the secondary phloem could be classified according to the following types: 1a. Phloem fibres in concentric bands alternating with bands ofaxial parenchyma devoid of crystals and sieve elements; 1b. Fibre-sclereids (sclerotic fibres) in concentric bands; 2. As 1a, but fibre bands f1anked by chambered crystalliferous parenchyma; 3a. Broad rays sclerified and extending fanwise or with a very large clump of sclereids; 3b. In species with only narrow wood rays, part of the rays dilated to produce fanwise extensions; 4. Aggregate rays with fanwise extensions; 5. Phloem fibres in round or spindle-shaped clusters or irregular, short bands; 6. Phloem sclereids in round or spindle-shaped clusters or irregular, short bands; 7. Diffuse distribution of all phloem elements; 8. Convergence ofrays towards the cortex.
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Renzi, Marsilio, Paul Copini, Anna R. Taddei, Antonio Rossetti, Lorenzo Gallipoli, Angelo Mazzaglia, and Giorgio M. Balestra. "Bacterial Canker on Kiwifruit in Italy: Anatomical Changes in the Wood and in the Primary Infection Sites." Phytopathology® 102, no. 9 (September 2012): 827–40. http://dx.doi.org/10.1094/phyto-02-12-0019-r.
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The bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae is a severe threat to kiwifruit production worldwide. Many aspects of P. syringae pv. actinidiae biology and epidemiology still require in-depth investigation. The infection by and spread of P. syringae pv. actinidiae in xylem and phloem was investigated by carrying out artificial inoculation experiments with histological and dendrochronological analyses of naturally diseased plants in Italy. We found that the bacterium can infect host plants by entering natural openings and lesions. In naturally infected kiwifruit plants, P. syringae pv. actinidiae is present in the lenticels as well as in the dead phloem tissue beneath the lenticels, surrounded by a lesion in the periderm which appears to indicate the importance of lenticels to kiwifruit infection. Biofilm formation was observed outside and inside plants. In cases of advanced stages of P. syringae pv. actinidiae infection, neuroses of the phloem occur, which are followed by cambial dieback and most likely by infection of the xylem. Anatomical changes in wood such as reduced ring width, a drastic reduction in vessel size, and the presence of tyloses were observed within several infected sites. In the field, these changes occur only a year after the first leaf symptoms are observed suggesting a significant time lapse between primary and secondary symptoms. It was possible to study the temporal development of P. syringae pv. actinidiae-induced cambial dieback by applying dendrochronology methods which revealed that cambial dieback occurs only during the growing season.
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Rajput, Kishore S. "Development of successive cambia and wood structure in stem of Rivea hypocriteriformis (Convolvulaceae)." Polish Botanical Journal 61, no. 1 (July 1, 2016): 89–98. http://dx.doi.org/10.1515/pbj-2016-0003.
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Abstract This study examined the formation of successive rings of cambia in Rivea hypocriteriformis Choisy (Convolvulaceae). The mature stem is composed of four to five rings of xylem alternating with phloem. Successive cambia originate as smaller and larger segments; union and anastomosing of small cambial segments often leads to the formation of discontinuous rings. In the initial stage of growth, several vascular bundles interconnect to form the first ring of vascular cambium. The cambium remains functional for one complete season and becomes dormant during summer; a new ring of cambium is completed prior to the subsequent monsoon season and sprouting of new leaves. Successive cambia are initiated from the pericyclic parenchyma situated three to four cell layers outside of the protophloem. Functionally, all the successive cambia are bidirectional and produce secondary xylem centripetally and phloem centrifugally. The secondary xylem is diffuse-porous, with indistinct growth rings and consisting of wide fibriform vessels, fibre tracheids, and axial and ray parenchyma cells. The xylem rays are uni- to multiseriate and heterocellular. The multiseriate rays contain lignified marginal ray cells and thin-walled, unlignified central cells. The central ray cells also show accumulations of starch and druses. Discrete strands of intraxylary phloem occur at the periphery of the pith, and additional intraxylary phloem develops from adjacent cells as secondary growth progresses. Earlier-formed phloem shows heavy accumulation of callose, followed by its compaction. The development of successive cambia is correlated with extension growth and with the phenology of the plant.
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Cevallos-Ferriz, Sergio R. S., and Ruth A. Stockey. "Vegetative Remains of the Rosaceae from the Princeton Chert (Middle Eocene) of British Columbia." IAWA Journal 11, no. 3 (1990): 261–80. http://dx.doi.org/10.1163/22941932-90001183.
Full textAbstract:
Several anatomieally preserved twigs, a branehing speeimen and the wood of a large axis with affinities to Rosaeeae are deseribed from the Prineeton ehert (Middle Eoeene) of British Columbia, Canada. Speeimens are eharaeterised by a heteroeellular pith with a peri-medullary rone of thiek-walled oval eells and semi-ring-porous seeondary xylem with vertieal traumatie duets, fibres with eireular bordered pits, and mostly seanty paratracheal and oeeasionally apotracheal parenehyma. Ray to vessel pitting is similar to the alternate intervaseular pitting. Seeondary phloem is eomposed of tangentially oriented diseontinuous bands of alternating fibres and thinwalled eells. Seeondary eortical tissues are represented by a phelloderm eharaeterised by rectangular eells and phellern with rectangular eoneave eells. Anatomical variation between speeimens can be related to age of the woody axes. Juvenile and mature wood of this speeies differ in vessel arrangement and presenee of scanty paratracheal parenchyma in mature wood. Vessel elements are arranged in radial multiples, oeeasional clusters as well as solitary vessels. Tyloses and dark cellular contents are present mainly in mature wood. Some twigs have a heterocellular pith with a few scattered cells with dark contents or, occasionally, short irregular rows of these cells. In the branching specimen eells of this type also are organised in longer rows. Together, these anatomical features suggest that all specimens belong to the same taxon, Prunus allenbyensis Cevallos-Ferriz ' Stockey n. sp. Anatomy of this plant reinforces the interpretation of a subtropical to temperate climate during the time of deposition.
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Brlansky, R. H., D. S. Howd, P. Broadbent, and V. D. Damsteegt. "Histology of Sweet Orange Stem Pitting Caused by an Australian Isolate of Citrus tristeza virus." Plant Disease 86, no. 10 (October 2002): 1169–74. http://dx.doi.org/10.1094/pdis.2002.86.10.1169.
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Some strains of the Citrus tristeza virus (CTV) cause stem pitting in sweet orange (Citrus sinensis (L.) Osbeck). This abnormality causes tree decline and reduction in fruit size and yield of affected citrus trees. Stem-pitting symptoms can occur on trunks, on all sizes of limbs, and on the twigs where fruit are produced. Variously sized pits or grooves in the wood often contain a yellow gum. Irregular growth of the phloem occurs in the area of these xylem pits. The histology of stem pitting caused by an Australian CTV isolate was studied in sweet orange using light and electron microscopy. Using scanning electron microscopy, details of the wood pits containing the gumming material were revealed. In thin sections of bark tissue, outgrowths of the phloem tissue were found at various intervals that corresponded to the pits in the wood. Higher numbers of viral inclusions were detected in the phloem outgrowths than were present in the other sieve elements.
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Tippett, Joanna T. "Formation and Fate of Kino Veins in Eucalyptus L'hérit." IAWA Journal 7, no. 2 (1986): 137–43. http://dx.doi.org/10.1163/22941932-90000975.
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Kino veins, generally referred to as gum veins, are formed in Eucalyptus spp. in response to injury. Although they are retained as defects in the wood of many species, in some they become inc1uded in the phloem, then the rhytidome and are eventually shed. Ninety-three Eucalyptus spp. were sampled to determine whether they had xylem or phloem (bark) veins. The species which exhibited kino veins in the phloem were all members of three sections of the subgenus Symphyomyrtus. All species examined of the subgenera Monocalyptus and Corymbia had xylem veins. Kino veins are formed by the lysigenous breakdown of parenchyma bands produced by the cambium. The difference which results in the veins either being shed in the bark or inc1uded in the xylem is determined at the time of their initiation. The parenchyma bands may be produced on either the xylem or on the phloem side of the cambium. The fate of the veins becomes apparent once normal cambial divisions resurne the production of xylem and phloem.
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Dute, Roland R., Paul J. Zwack, Ebony Craig, and Steven M. Baccus. "Torus Presence and Distribution in Leaves of Osmanthus Armatus." IAWA Journal 33, no. 3 (2012): 257–68. http://dx.doi.org/10.1163/22941932-90000092.
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Osmanthus armatus Diels is a member of the Oleaceae whose woody branches were previously found to possess torus-bearing pit membranes. Observations of the perennial leaves indicate that torus-bearing, pitted tracheary elements extend throughout the vasculature of the organ including the veins delimiting the areoles and the vein termini. Torusbearing tracheary elements differentiate into the vein termini but do not develop at the very ends. Rather, the distal ends of vein termini consist of tracheids without tori and of phloem containing intermediary cells. The latter cell type is a component of the phloem in the small diameter leaf veins. Tori are considered to be xeromorphic features which, along with a thick cuticle and sclereids, are advantageous for the perennial growth habit of the leaves.
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Kordan, Bożena, Katarzyna Stec, Paweł Słomiński, Marian J. Giertych, Anna Wróblewska-Kurdyk, and Beata Gabrys. "Susceptibility of forage legumes to infestation by the pea aphid Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae)." Crop and Pasture Science 69, no. 8 (2018): 775. http://dx.doi.org/10.1071/cp18065.
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The small-seeded legumes are important forage crops for grazing animals and contribute nitrogen to succeeding crops in crop rotation systems. However, the susceptibility of several of the forage legumes to the specialist pea aphid Acyrthosiphon pisum (Harris) has never been investigated. The present study on aphid probing behaviour using the Electrical Penetration Graph technique revealed that the forage legumes studied were (i) highly acceptable (common vetch Vicia sativa L.), (ii) acceptable (wooly vetch Vicia villosa Roth), (iii) moderately acceptable (fodder galega Galega orientalis Lam., crimson clover Trifolium incarnatum L., Persian clover Trifolium resupinatum L., white clover Trifolium repens L.), (iv) barely acceptable (common bird’s-foot-trefoil Lotus corniculatus L., yellow lucerne Medicago falcata L., alfalfa Medicago sativa L., sand lucerne Medicago × varia Martyn, common bird’s-foot Ornithopus sativus Brot., alsike clover Trifolium hybridum L., red clover Trifolium pratense L., common sainfoin Onobrychis viciifolia Scop.), and (v) unacceptable (white melilot Melilotus albus Medik.) to the pea aphid. On (i) plants, probing occupied 85% of experimental time, all aphids (100%) succeeded in feeding on phloem sap, phloem phase occupied 50% of probing time, sap ingestion periods were long (mean duration: 100.8 ± 28.2 min.) and engaged 97% of the phloem phase. On (ii) plants, probing occupied 73% of exp. time, feeding activity occurred in 66.7% of aphids, phloem phase occupied 30% of probing time, sap ingestion periods were long (mean duration: 115.5 ± 46.7 min) and engaged 80% of the phloem phase. On (iii) plants, probing ranged from 53% of exp. time on T. repens to 70% on T. incarnatum and T. resuspinatum, feeding occurred in 35.3% of aphids on T. resuspinatum up to 54.5% on T. incarnatum, phloem phase occupied 10% of exp. time on G. orientalis, T. incarnatum, and T. resuspinatum and 20% on T. repens, sap ingestion periods were from 9.8 ± 1.8 min. on G. orientalis to 51.9 ± 20.7 min. long on T. resuspinatum and engaged from 30% of phloem phase on G. orientalis to 80% on T. incarnatum. On (iv) plants, probing occupied 25% of exp. time on O. viciifolia up to 38% on O. sativus and T. hybridum, feeding occurred in 6.7% of aphids on T. hybridum to 28% on O. sativus, phloem phase occupied less than 1% of probing time on all plants except O. viciifolia (4%) and O. sativus (5%) and it consisted mainly of salivation. On M. albus (v), probing occupied 22% of experimental time, the probes were short (1.8 ± 0.3 min), and no aphid on M. albus showed feeding on phloem sap. M. albus can be recommended for intercropping, ‘push-pull’ strategies, or as a barrier crop against A. pisum in sustainable agricultural practices.
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Chery, Joyce G., Israel L. da Cunha Neto, Marcelo R. Pace, Pedro Acevedo-Rodríguez, Chelsea D. Specht, and Carl J. Rothfels. "Wood anatomy of the neotropical liana lineage Paullinia L. (Sapindaceae)." IAWA Journal 41, no. 3 (July 28, 2020): 278–300. http://dx.doi.org/10.1163/22941932-bja10027.
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Abstract The liana genus Paullinia L. is one of the most speciose in the neotropics and is unusual in its diversity of stem macromorphologies and cambial conformations. These so-called “vascular cambial variants” are morphologically disparate, evolutionarily labile, and are implicated in injury repair and flexibility. In this study, we explore at the finer scale how wood anatomy translates into functions related to the climbing habit. We present the wood anatomy of Paullinia and discuss the functional implications of key anatomical features. Wood anatomy characters were surveyed for 21 Paullinia species through detailed anatomical study. Paullinia woods have dimorphic vessels, rays of two size classes, and both septate and non-septate fibers. Fibriform vessels, fusiform axial parenchyma, and elements morphologically intermediate between fibers and axial parenchyma were observed. Prismatic crystals are common in the axial and/or ray parenchyma, and laticifers are present in the cortex and/or the early-formed secondary phloem. Some features appear as unique to Paullinia or the Sapindaceae, such as the paucity of axial parenchyma and the abundance of starch storing fibers. Although many features are conserved across the genus, the Paullinia wood anatomy converges on several features of the liana-specific functional anatomy expressed across distantly related lianas, demonstrating an example of convergent evolution. Hence, the conservation of wood anatomy in Paullinia suggests a combination of phylogenetic constraint as a member of Sapindaceae and functional constraint from the liana habit.
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Heklau, Heike, Peter Gasson, Fritz Schweingruber, and Pieter Baas. "Wood Anatomy of Chenopodiaceae (Amaranthaceae s.l.)." IAWA Journal 33, no. 2 (2012): 205–32. http://dx.doi.org/10.1163/22941932-90000090.
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The wood anatomy of the Chenopodiaceae is distinctive and fairly uniform. The secondary xylem is characterised by relatively narrow vessels (<100 μm) with mostly minute pits (<4 μm), and extremely narrow vessels (<10 μm intergrading with vascular tracheids in addition to “normal” vessels), short vessel elements (<270 μm), successive cambia, included phloem, thick-walled or very thick-walled fibres, which are short (<470 μm), and abundant calcium oxalate crystals. Rays are mainly observed in the tribes Atripliceae, Beteae, Camphorosmeae, Chenopodieae, Hablitzieae and Salsoleae, while many Chenopodiaceae are rayless. The Chenopodiaceae differ from the more tropical and subtropical Amaranthaceae s.str. especially in their shorter libriform fibres and narrower vessels. Contrary to the accepted view that the subfamily Polycnemoideae lacks anomalous thickening, we found irregular successive cambia and included phloem. They are limited to long-lived roots and stem borne roots of perennials (Nitrophila mohavensis) and to a hemicryptophyte (Polycnemum fontanesii). The Chenopodiaceae often grow in extreme habitats, and this is reflected by their wood anatomy. Among the annual species, halophytes have narrower vessels than xeric species of steppes and prairies, and than species of nitrophile ruderal sites.
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Zhengli, Li, and Cui Keming. "Differentiation of Secondary Xylem After Girdling." IAWA Journal 9, no. 4 (1988): 375–83. http://dx.doi.org/10.1163/22941932-90001099.
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Under favourable growth season and by suitable technical means, regeneration and continuous growth of new bark after girdling has been observed in many trees. Differentiation of the secondary xylem varies after arteficial treatment. Thus , the authors consider that (1) under appropriate conditions most trees could be girdled on a large scale with subsequent new bark regeneration and continued growth, (2) after removal of the phloem the living cells of the secondary xylem, i.e., wood parenchyma cells, may function in transporting nutrients from the treecrown downwards, and (3) finally, after girdling or when cultured in vitro, both immature xylem and phloem can dedifferentiate into meristematic tissue that further develops vascular tissue.
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Krokene, Paal, and Halvor Solheim. "Growth of four bark-beetle-associated blue-stain fungi in relation to the induced wound response in Norway spruce." Canadian Journal of Botany 75, no. 4 (April 1, 1997): 618–25. http://dx.doi.org/10.1139/b97-069.
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Twenty-five-year-old Norway spruce trees (Picea abies) were inoculated with four blue-stain fungi. Each tree was inoculated three times with each fungus and three times with sterile agar as a control, giving a total of 15 inoculations per tree. There was little variation in the extent of phloem necrosis produced in response to the different fungi, but 5 weeks after inoculation necroses induced by Ceratocystis polonica and Ambrosiella sp. were significantly longer than those for the other fungi. At the same time, C. polonica had induced sapwood desiccation twice as deeply into the wood as any other fungus. Hyphal growth of the fungi into phloem and sapwood followed the same pattern as necrosis length and desiccation depth. Five weeks after inoculation, C. polonica had penetrated phloem and sapwood farther than any other fungus. It grew more slowly than the other fungi in both tissues the first week after inoculation, but the four following weeks it grew more quickly than all other fungi. Key words: Ambrosiella, blue-stain fungi, Ceratocystis polonica, low-density inoculation, Ophiostoma piceae, Scolytidae.
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Fink, Siegfried. "Microscopical Investigations on Wood Formation and Function in Dlseased Trees." IAWA Journal 7, no. 4 (1986): 351–55. http://dx.doi.org/10.1163/22941932-90001005.
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Histologieal and histochemical investigations were performed on the xylem, cambium, and phloem of Abies alba and Picea abies affected by forest decline ('Waldsterben', 'Neuartige Waldschäden'). In comparison to healthy trees the annual inerement was reduced and correspondingly the active cambial zone was sm aller. No differenees were found in the peroxidase activities in the differentiating tracheids undergoing lignification, and no change in lignin content eould be deteeted UV-photometrieally in the walls of the traeheids of affeeted trees. In general, mueh less starch reserves in the parenchymatous elements of the diseased trees were observed during autumn and spring. Correspondingly, the aetivities of enzymes involved in the mobilisation and transport of these earbohydrates were lower in spring. With the use of fluorescent markers it eould be demonstrated that apparently some areas of the sapwood do not take part any longer in the water conduetion in diseased trees. In most eases differenees between healthy and diseased trees were much more pronounced in fir than in spruce. Furthermore, diseased firs showed a special pathological reaetion with the formation of large mueilage cells in the non-funetional phloem and of oecasional traumatie resin canal barriers in the xylem.
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Schweingruber, Fritz Hans. "Anatomical Characteristics and Ecological Trends in the Xylem and Phloem of Brassicaceae and Resedacae." IAWA Journal 27, no. 4 (2006): 419–42. http://dx.doi.org/10.1163/22941932-90000164.
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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.
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Georg Richter, Hans. "Wood and Bark Anatomy of Lauraceae. ii. Licaria Aublet." IAWA Journal 6, no. 3 (1985): 187–99. http://dx.doi.org/10.1163/22941932-90000938.
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Qualitative features of the secondary xylem of Licaria present a rather uniform structural profile. Constant differences in primarily quantitative characters lead to the formation of speeies groups wh ich loosely correspond to infrageneric sections based on floral and vegetative morphology. This subdivision is strongly corroborated by the highly variable secondary phloem structurc revealing considerable diversity in type and distribution of sc1erenchymatic tissues. Inorganic inclusions in the secondary xylem, crystals and silica, constitute an important diagnostic tool for differentiating certain species and species groups, but are hardly of importance in the bark.
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Carlquist, Sherwin. "Wood Anatomy and Relationships of Duckeodendraceae and Goetzeaceae." IAWA Journal 9, no. 1 (1988): 3–12. http://dx.doi.org/10.1163/22941932-90000460.
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Duckeodendron has been referred to Solanaceae, Boraginaceae, and Apocynaceae; segregation into its own family is based on its drupoid fruits. Drupoid fruits also characterise Goetzeaceae, which have been placed within Sapotaceae and within Solanaceae by particular authors. Both Duckeodendraceae and Goetzeaceae have intraxylary phloem (a characteristic of Solanaceae but absent from most dicotyledon families) and wood features entirely congruent with the concept that they are elosely related to Solanaceae. Wood of Duckeodendron is very sirnilar to that of Nothocestrum (Solanaceae). Wood of Goetzeaceae is most like wood of the solanaceous genera Grabowskya and Lycium. Duckeodendraceae and Goetzeaceae may be regarded as satellite farnilies of Solanaceae, in accord with the treatment of Hunziker (1979), or could conceivably be treated as subfarnilies of Solanaceae. Qualitative and quantitative features are given for wood of Duckeodendron cestroides (Duckeodendraceae) and two speeies of Goetzeaceae: Espadaea amoena and Henoonia myrtifolia. Wood of Duckeodendron is elearly mesomorphic. Wood of Espadaea is intermediate, and wood of Henoonia is relatively xeromorphic as based on vessel element dimensions, vessel density, and vasicentric tracheid presence.
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Salleo, Sebastiano, Patrizia Trifilò, and Maria A. Lo Gullo. "Phloem as a possible major determinant of rapid cavitation reversal in stems of Laurus nobilis (laurel)." Functional Plant Biology 33, no. 11 (2006): 1063. http://dx.doi.org/10.1071/fp06149.
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Xylem recovery from embolism was studied in stems of Laurus nobilis L. that were induced to cavitate by combining negative xylem pressures with positive air pressures applied with a pressure collar. Xylem refilling was measured 2 and 20 min and 15 h after air pressure release in January, March and June when increasing percentages of wood parenchyma cells with high starch content (HSC-VAC) were counted (from 0% in January to 87.3% in June). In January, no xylem repair was measured. In June, stems refilled by 75% of previous conductivity loss with a parallel decrease of HSC-VAC. Xylem refilling was tested for stems with phloem either intact or excised by 20 and 50% and with phloem inactivated by girdling stems at both sides of the embolised segment. Stems with 50% of the cortex removed showed some recovery 15 h after embolism. Girdled stems did not recover from embolism and no starch depolymerisation was measured. Girdled stems where a radial mechanical pressure was applied for 20 min after embolism refilled in the same way as stems with intact phloem. Our conclusion is that phloem may export some signal for starch depolymerisation and this, in turn, would drive sugar efflux into embolised conduits with consequent osmotic water flows and refilling.
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Davison, E. M. "Invasion of Phloem and Xylem of Woody Stems and Roots ofEucalyptus marginataandPinus radiatabyPhytophthora cinnamomi." Phytopathology 84, no. 4 (1994): 335. http://dx.doi.org/10.1094/phyto-84-335.
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Carlquist, Sherwin. "Wood and Stem Anatomy of Petiveria and Rivina (Caryophyllales); Systematic Implications." IAWA Journal 19, no. 4 (1998): 383–91. http://dx.doi.org/10.1163/22941932-90000659.
Full textAbstract:
Petiveria and Rivina have been placed by various authors close to each other within Phytolaccaceae; widely separated from each other but both within Phytolaccaceae; and within a segregate family (Rivinaceae) but still within the order Caryophyllales. Wood of these monotypic genera proves to be alike in salient qualitative and even quantitative features, including presence of a second cambium, vessel morphology and pit size, nonbordered perforation plates, vasicentric axial parenchyma type, fiber-tracheids with vestigially bordered pits and starch contents, narrow multiseriate rays plus a few uniseriate rays, ray cells predominantly upright and with thin lignified walls and starch content, and presence of both large styloids and packets of coarse raphides in secondary phloem. Although further data are desirable, wood and stern data do not strongly support separation of Petiveria and Rivina from Phytolaccaceae. Quantitative wood features correspond to the short-lived perennial habit ofboth genera, and are indicative ofaxeromorphic wood pattern.
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Mennega, Alberta M. W. "Wood Anatomy of the Hippocrateoideae (Celastraceae)." IAWA Journal 18, no. 4 (1997): 331–68. http://dx.doi.org/10.1163/22941932-90001501.
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In this paper the wood anatomy of the subfarnily Hippocrateoideae of the Celastraceae is treated. Halle's division (1986, 1990) of the subfarnily into four tribes, chiefly based on material of tropical Africa: viz. Salacieae, Campylostemoneae, Helictonemeae and Hippocrateae is followed. In a recent issue of the Flora of the Guianas the Hippocrateaceae - there treated as aseparate farnily - were divided into Hippocrateoideae and Salacioideae. This bipartition was reflected in the wood structure of the genera studied (Mennega 1994). Here the wood structure of all genera worldwide (24), except the Asian genus Arnicratea, is described. It appeared that again a subdivision into two distinct anatomical groups could be made, with the three last tribes mentioned above showing the same characteristic structure as found before in New World Hippocrateae/Hippocrateoideae. The most important features of this group are the presence of very wide and very high rays, in a number of genera with unlignified ray cells at the growth ring border, the absence of included phloem tissue, and in many species an intruding bark resulting in an indented wood pattern in stern cross sections or even an intricate pattern of deep furrows. The Salacieae/Salacioideae on the other hand are characterized by narrow, not exceptionally high rays, absence of unlignified ray cells, the occurrence of septate fibres in a parenchyma-like distribution, and often by the presence of included phloem tissue, either as isolated strands or more often as conspicuous concentric bands, or as irregular bands with radial connections. Features present in all genera are: vessels with simple perforation plates, preponderance of solitary vessels, wide and narrow vessels distributed at random, alternate pitting; fibretracheids, and libriform nonseptate and septate fibres present; axial parenchyma scanty paratracheal or as rare isolated strands; rays heterogeneous, the cell types irregularly distributed, rhombic crystals numerous, often in characteristic radial distribution. Campylostemon, considered in the past by some taxonornists as belonging in Celastraceae or as intermediate between Hippocrateaceae and Celastraceae, closely resembles Hippocrateae in its wood anatomy. And it is especially this group that by its characteristic features -like the wide rays - is more different from Celastraceae in general than Salacieae, which have several features in common with genera of Celastraceae.