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Brigitte Meyer-berthaud - One of the best experts on this subject based on the ideXlab platform.
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Secondary Phloem in Early Carboniferous Seed Plants: Anatomical Diversity and Evolutionary Implications
International Journal of Plant Sciences, 2014Co-Authors: Anne-laure Decombeix, Jean Galtier, Brigitte Meyer-berthaudAbstract:International audiencePremise of research.Secondary Phloem produced by a bifacial vascular cambium is the distinctive feature of lignophytes, the group that comprises the seed plants and the progymnosperms. Because Secondary Phloem is rarely well preserved in the fossil record, our knowledge of the evolution of this tissue remains incomplete. Methodology: We illustrate the Secondary Phloem anatomy of nine seed plants of Mississippian (Early Carboniferous) age that represent to date the oldest representatives of the group in which this tissue is well preserved. In addition, we review the information available on the Secondary Phloem anatomy of Devonian progymnosperms and Late Carboniferous–Permian seed plants. Pivotal results: Secondary Phloem anatomy was already diversified in the Mississippian seed plants, in terms of cell composition and spatial organization of the different cell types. We propose four models of Secondary Phloem anatomy and organization in lignophytes of Devonian-Carboniferous age. Conclusions: The diversity of Secondary Phloem anatomy in Mississippian seed plants parallels what is observed for other parts of their vascular system; it is most likely linked to the Mississippian diversification of seed plant growth architectures and habitats. The accumulated fossil evidence also demonstrates that several characters that have been considered as advanced on the basis of the study of extant gymnosperms (e.g., the presence of fibers in the functional Phloem and the arrangement in alternate tangential layers of a same cell type) were actually already present in some early representatives of the lignophyte
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Secondary Phloem in Early Carboniferous Seed Plants: Anatomical Diversity and Evolutionary Implications
International Journal of Plant Sciences, 2014Co-Authors: Anne-laure Decombeix, Jean Galtier, Brigitte Meyer-berthaudAbstract:Premise of research. Secondary Phloem produced by a bifacial vascular cambium is the distinctive feature of lignophytes, the group that comprises the seed plants and the progymnosperms. Because Secondary Phloem is rarely well preserved in the fossil record, our knowledge of the evolution of this tissue remains incomplete.Methodology. We illustrate the Secondary Phloem anatomy of nine seed plants of Mississippian (Early Carboniferous) age that represent to date the oldest representatives of the group in which this tissue is well preserved. In addition, we review the information available on the Secondary Phloem anatomy of Devonian progymnosperms and Late Carboniferous–Permian seed plants.Pivotal results. Secondary Phloem anatomy was already diversified in the Mississippian seed plants, in terms of cell composition and spatial organization of the different cell types. We propose four models of Secondary Phloem anatomy and organization in lignophytes of Devonian-Carboniferous age.Conclusions. The diversity o...
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Secondary Phloem in Early Carboniferous seed plants: anatomical diversity and evolutionary implications
International Journal of Plant Sciences, 2014Co-Authors: Anne-laure Decombeix, Brigitte Meyer-berthaud, Jean GaltierAbstract:Premise of research.Secondary Phloem produced by a bifacial vascular cambium is the distinctive feature of lignophytes, the group that comprises the seed plants and the progymnosperms. Because Secondary Phloem is rarely well preserved in the fossil record, our knowledge of the evolution of this tissue remains incomplete. Methodology: We illustrate the Secondary Phloem anatomy of nine seed plants of Mississippian (Early Carboniferous) age that represent to date the oldest representatives of the group in which this tissue is well preserved. In addition, we review the information available on the Secondary Phloem anatomy of Devonian progymnosperms and Late Carboniferous–Permian seed plants. Pivotal results: Secondary Phloem anatomy was already diversified in the Mississippian seed plants, in terms of cell composition and spatial organization of the different cell types. We propose four models of Secondary Phloem anatomy and organization in lignophytes of Devonian-Carboniferous age. Conclusions: The diversity of Secondary Phloem anatomy in Mississippian seed plants parallels what is observed for other parts of their vascular system; it is most likely linked to the Mississippian diversification of seed plant growth architectures and habitats. The accumulated fossil evidence also demonstrates that several characters that have been considered as advanced on the basis of the study of extant gymnosperms (e.g., the presence of fibers in the functional Phloem and the arrangement in alternate tangential layers of a same cell type) were actually already present in some early representatives of the lignophytes
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A Callixylon (Archaeopteridales, Progymnospermopsida) trunk with preserved Secondary Phloem from the Late Devonian of Morocco.
American Journal of Botany, 2013Co-Authors: Anne-laure Decombeix, Brigitte Meyer-berthaudAbstract:Premise of the study: During the Devonian, the evolution of Secondary Phloem produced by a bifacial vascular cambium was a key innovation that increased the ability of plants within the lignophyte clade to redistribute photosynthates and other organic compounds throughout their body. Unraveling the Secondary Phloem anatomy of the first arborescent lignophytes is crucial to understand the evolution of this tissue and the physiology of early trees. * Methods: A 10 cm wide stem of Callixylon with preserved Secondary Phloem from the Famennian of Morocco is described using thin-sections. * Key results: The Secondary Phloem of this Callixylon zalesskyi-type of stem is composed of fibers, sclereids, rays, axial parenchyma, and putative sieve cells. Fibers differentiate early and are relatively abundant in the inner Phloem. In the older Phloem, fibers are arranged in tangential bands alternating with extensive layers of axial parenchyma. Changes between the young and old Phloem involve the periclinal division and radial elongation of the axial parenchyma cells. The presence of fibers in the inner, presumably functional Phloem, combined with evidence for rhythmicity in the production of different Phloem cell types are documented for the first time in detail in an archaeopteridalean progymnosperm. No periderm was observed within the preserved seven millimeters of bark tissues. * Conclusions: The Secondary Phloem anatomy supports a close affinity of archaeopteridalean progymnosperms with both aneurophytalean progymnosperms and seed plants. The production of Secondary Phloem might have provided an advantage to these first arborescent lignophytes over other types of Devonian early trees, especially in dry conditions.
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A Callixylon (Archaeopteridales, Progymnospermopsida) trunk with preserved Secondary Phloem from the Late Devonian of Morocco.
American journal of botany, 2013Co-Authors: Anne-laure Decombeix, Brigitte Meyer-berthaudAbstract:During the Devonian, the evolution of Secondary Phloem produced by a bifacial vascular cambium was a key innovation that increased the ability of plants within the lignophyte clade to redistribute photosynthates and other organic compounds throughout their body. Unraveling the Secondary Phloem anatomy of the first arborescent lignophytes is crucial to understand the evolution of this tissue and the physiology of early trees. A 10 cm wide stem of Callixylon with preserved Secondary Phloem from the Famennian of Morocco is described using thin-sections. The Secondary Phloem of this Callixylon zalesskyi-type of stem is composed of fibers, sclereids, rays, axial parenchyma, and putative sieve cells. Fibers differentiate early and are relatively abundant in the inner Phloem. In the older Phloem, fibers are arranged in tangential bands alternating with extensive layers of axial parenchyma. Changes between the young and old Phloem involve the periclinal division and radial elongation of the axial parenchyma cells. The presence of fibers in the inner, presumably functional Phloem, combined with evidence for rhythmicity in the production of different Phloem cell types are documented for the first time in detail in an archaeopteridalean progymnosperm. No periderm was observed within the preserved seven millimeters of bark tissues. The Secondary Phloem anatomy supports a close affinity of archaeopteridalean progymnosperms with both aneurophytalean progymnosperms and seed plants. The production of Secondary Phloem might have provided an advantage to these first arborescent lignophytes over other types of Devonian early trees, especially in dry conditions.
Anne-laure Decombeix - One of the best experts on this subject based on the ideXlab platform.
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Secondary Phloem in Early Carboniferous Seed Plants: Anatomical Diversity and Evolutionary Implications
International Journal of Plant Sciences, 2014Co-Authors: Anne-laure Decombeix, Jean Galtier, Brigitte Meyer-berthaudAbstract:International audiencePremise of research.Secondary Phloem produced by a bifacial vascular cambium is the distinctive feature of lignophytes, the group that comprises the seed plants and the progymnosperms. Because Secondary Phloem is rarely well preserved in the fossil record, our knowledge of the evolution of this tissue remains incomplete. Methodology: We illustrate the Secondary Phloem anatomy of nine seed plants of Mississippian (Early Carboniferous) age that represent to date the oldest representatives of the group in which this tissue is well preserved. In addition, we review the information available on the Secondary Phloem anatomy of Devonian progymnosperms and Late Carboniferous–Permian seed plants. Pivotal results: Secondary Phloem anatomy was already diversified in the Mississippian seed plants, in terms of cell composition and spatial organization of the different cell types. We propose four models of Secondary Phloem anatomy and organization in lignophytes of Devonian-Carboniferous age. Conclusions: The diversity of Secondary Phloem anatomy in Mississippian seed plants parallels what is observed for other parts of their vascular system; it is most likely linked to the Mississippian diversification of seed plant growth architectures and habitats. The accumulated fossil evidence also demonstrates that several characters that have been considered as advanced on the basis of the study of extant gymnosperms (e.g., the presence of fibers in the functional Phloem and the arrangement in alternate tangential layers of a same cell type) were actually already present in some early representatives of the lignophyte
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Secondary Phloem in Early Carboniferous Seed Plants: Anatomical Diversity and Evolutionary Implications
International Journal of Plant Sciences, 2014Co-Authors: Anne-laure Decombeix, Jean Galtier, Brigitte Meyer-berthaudAbstract:Premise of research. Secondary Phloem produced by a bifacial vascular cambium is the distinctive feature of lignophytes, the group that comprises the seed plants and the progymnosperms. Because Secondary Phloem is rarely well preserved in the fossil record, our knowledge of the evolution of this tissue remains incomplete.Methodology. We illustrate the Secondary Phloem anatomy of nine seed plants of Mississippian (Early Carboniferous) age that represent to date the oldest representatives of the group in which this tissue is well preserved. In addition, we review the information available on the Secondary Phloem anatomy of Devonian progymnosperms and Late Carboniferous–Permian seed plants.Pivotal results. Secondary Phloem anatomy was already diversified in the Mississippian seed plants, in terms of cell composition and spatial organization of the different cell types. We propose four models of Secondary Phloem anatomy and organization in lignophytes of Devonian-Carboniferous age.Conclusions. The diversity o...
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Secondary Phloem in Early Carboniferous seed plants: anatomical diversity and evolutionary implications
International Journal of Plant Sciences, 2014Co-Authors: Anne-laure Decombeix, Brigitte Meyer-berthaud, Jean GaltierAbstract:Premise of research.Secondary Phloem produced by a bifacial vascular cambium is the distinctive feature of lignophytes, the group that comprises the seed plants and the progymnosperms. Because Secondary Phloem is rarely well preserved in the fossil record, our knowledge of the evolution of this tissue remains incomplete. Methodology: We illustrate the Secondary Phloem anatomy of nine seed plants of Mississippian (Early Carboniferous) age that represent to date the oldest representatives of the group in which this tissue is well preserved. In addition, we review the information available on the Secondary Phloem anatomy of Devonian progymnosperms and Late Carboniferous–Permian seed plants. Pivotal results: Secondary Phloem anatomy was already diversified in the Mississippian seed plants, in terms of cell composition and spatial organization of the different cell types. We propose four models of Secondary Phloem anatomy and organization in lignophytes of Devonian-Carboniferous age. Conclusions: The diversity of Secondary Phloem anatomy in Mississippian seed plants parallels what is observed for other parts of their vascular system; it is most likely linked to the Mississippian diversification of seed plant growth architectures and habitats. The accumulated fossil evidence also demonstrates that several characters that have been considered as advanced on the basis of the study of extant gymnosperms (e.g., the presence of fibers in the functional Phloem and the arrangement in alternate tangential layers of a same cell type) were actually already present in some early representatives of the lignophytes
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A Callixylon (Archaeopteridales, Progymnospermopsida) trunk with preserved Secondary Phloem from the Late Devonian of Morocco.
American Journal of Botany, 2013Co-Authors: Anne-laure Decombeix, Brigitte Meyer-berthaudAbstract:Premise of the study: During the Devonian, the evolution of Secondary Phloem produced by a bifacial vascular cambium was a key innovation that increased the ability of plants within the lignophyte clade to redistribute photosynthates and other organic compounds throughout their body. Unraveling the Secondary Phloem anatomy of the first arborescent lignophytes is crucial to understand the evolution of this tissue and the physiology of early trees. * Methods: A 10 cm wide stem of Callixylon with preserved Secondary Phloem from the Famennian of Morocco is described using thin-sections. * Key results: The Secondary Phloem of this Callixylon zalesskyi-type of stem is composed of fibers, sclereids, rays, axial parenchyma, and putative sieve cells. Fibers differentiate early and are relatively abundant in the inner Phloem. In the older Phloem, fibers are arranged in tangential bands alternating with extensive layers of axial parenchyma. Changes between the young and old Phloem involve the periclinal division and radial elongation of the axial parenchyma cells. The presence of fibers in the inner, presumably functional Phloem, combined with evidence for rhythmicity in the production of different Phloem cell types are documented for the first time in detail in an archaeopteridalean progymnosperm. No periderm was observed within the preserved seven millimeters of bark tissues. * Conclusions: The Secondary Phloem anatomy supports a close affinity of archaeopteridalean progymnosperms with both aneurophytalean progymnosperms and seed plants. The production of Secondary Phloem might have provided an advantage to these first arborescent lignophytes over other types of Devonian early trees, especially in dry conditions.
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A Callixylon (Archaeopteridales, Progymnospermopsida) trunk with preserved Secondary Phloem from the Late Devonian of Morocco.
American journal of botany, 2013Co-Authors: Anne-laure Decombeix, Brigitte Meyer-berthaudAbstract:During the Devonian, the evolution of Secondary Phloem produced by a bifacial vascular cambium was a key innovation that increased the ability of plants within the lignophyte clade to redistribute photosynthates and other organic compounds throughout their body. Unraveling the Secondary Phloem anatomy of the first arborescent lignophytes is crucial to understand the evolution of this tissue and the physiology of early trees. A 10 cm wide stem of Callixylon with preserved Secondary Phloem from the Famennian of Morocco is described using thin-sections. The Secondary Phloem of this Callixylon zalesskyi-type of stem is composed of fibers, sclereids, rays, axial parenchyma, and putative sieve cells. Fibers differentiate early and are relatively abundant in the inner Phloem. In the older Phloem, fibers are arranged in tangential bands alternating with extensive layers of axial parenchyma. Changes between the young and old Phloem involve the periclinal division and radial elongation of the axial parenchyma cells. The presence of fibers in the inner, presumably functional Phloem, combined with evidence for rhythmicity in the production of different Phloem cell types are documented for the first time in detail in an archaeopteridalean progymnosperm. No periderm was observed within the preserved seven millimeters of bark tissues. The Secondary Phloem anatomy supports a close affinity of archaeopteridalean progymnosperms with both aneurophytalean progymnosperms and seed plants. The production of Secondary Phloem might have provided an advantage to these first arborescent lignophytes over other types of Devonian early trees, especially in dry conditions.
Jacqueline Lück - One of the best experts on this subject based on the ideXlab platform.
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Patterned cell development in the Secondary Phloem of dicotyledonous trees: a review and a hypothesis
Journal of Plant Research, 2006Co-Authors: Peter W Barlow, Jacqueline LückAbstract:The Secondary Phloem of dicotyledonous trees and shrubs is constructed of sieve tube cells (S) and their companion cells, as well as parenchyma (P) and fibre (F) cells. Different species have characteristic sequences of these S, P and F cells within the radial files of their Phloem. The sequences are recurrent, and are evidence of rhythmic cell determination and differentiation. A model was devised to account for the sequences found in various dicot tree species. It is based on the pattern of radial displacement of cells through a gradient of morphogen which supports Secondary Phloem development. According to this model, each tree species shows a particular pattern of post-mitotic cellular displacement along each radial file as a result of a corresponding sequence of periclinal division in the cambial initial and its descendents. The divisions and displacements ensure that at each timestep (equivalent to an interdivisional interval) each cell resides in a specific location within the morphogenic gradient. Cells then emerge from the post-mitotic zone of cell determination, having acquired different final positional values. These values lie above a series of thresholds that permit the respective determination and subsequent differentiation of one or other of the three cell types S, P and F. The recurrent nature of the sequences of the three cell types within each radial cell file, as well as their tangential banding, are a consequence of a shared rhythmic spatio-temporal pattern of periclinal cambial divisions. With a single set of morphogen parameters required for cell determination, and using three positions for cambial cell divisions, all the cellular sequences of Secondary Phloem illustrated in the literature can be accounted for.
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Repetitive cellular patterns in the Secondary Phloem of conifer and dicot trees, and a hypothesis for their development
Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2005Co-Authors: Peter W Barlow, Jacqueline LückAbstract:Abstract The radial fusiform cell files of the Secondary Phloem of conifers and dicots are composed of different cell types – fibres, parenchyma and sieve cells (in conifers), or sieve elements plus companion cells (in dicots). These cell types are arranged in characteristic, species-specific sequences along the radii of the files. The sequences are replicated in adjacent files and this leads to tangential bands of similar cell type. Moreover, the sequences are developed repetitively so that a sequence found in one year's growth increment of Phloem is repeated in the next increment. In some species, many repetitions of the same sequence occur within one annual increment. A general hypothesis has been developed to account for the radial sequences of cell types. It is proposed that there is a gradient of a Phloem-promoting morphogen, a series of morphogen thresholds for the determination of each Phloem cell type, and a particular spatio-temporal pattern of periclinal cell division in the Phloem domain of th...
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cell division systems that account for the various arrangements and types of differentiated cells within the Secondary Phloem of conifers
Plant Biosystems, 2004Co-Authors: Peter W Barlow, Jacqueline LückAbstract:There are two main types of arrangement of differentiated cells within the radial cell files of Secondary Phloem in conifer trees. In the C-type arrangement, characteristic of the Cupressaceae, fibre (F), parenchyma (P) and sieve (S) cells are arranged in recurrent groups, such as the “standard” cellular quartet (FSPS). In the P-type arrangement, characteristic of the Pinaceae, there are no fibres and one of the characteristic recurrent arrangements is the cellular sextet (PSSSSS). In addition, in both C-type and P-type arrangements, similar cell types are often organised into tangential bands. A simulation model, based on the theory of L-systems, was devised to account for the determination of these two types of regular and recurrent patterns of differentiated Phloem cells. It was based on the supposition that, in the meristematic portion of the Phloem domain, there are specific spatio-temporal patterns of periclinal cell division. When new cells are produced, those already present are displaced along th...
Peter W Barlow - One of the best experts on this subject based on the ideXlab platform.
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Patterned cell development in the Secondary Phloem of dicotyledonous trees: a review and a hypothesis
Journal of Plant Research, 2006Co-Authors: Peter W Barlow, Jacqueline LückAbstract:The Secondary Phloem of dicotyledonous trees and shrubs is constructed of sieve tube cells (S) and their companion cells, as well as parenchyma (P) and fibre (F) cells. Different species have characteristic sequences of these S, P and F cells within the radial files of their Phloem. The sequences are recurrent, and are evidence of rhythmic cell determination and differentiation. A model was devised to account for the sequences found in various dicot tree species. It is based on the pattern of radial displacement of cells through a gradient of morphogen which supports Secondary Phloem development. According to this model, each tree species shows a particular pattern of post-mitotic cellular displacement along each radial file as a result of a corresponding sequence of periclinal division in the cambial initial and its descendents. The divisions and displacements ensure that at each timestep (equivalent to an interdivisional interval) each cell resides in a specific location within the morphogenic gradient. Cells then emerge from the post-mitotic zone of cell determination, having acquired different final positional values. These values lie above a series of thresholds that permit the respective determination and subsequent differentiation of one or other of the three cell types S, P and F. The recurrent nature of the sequences of the three cell types within each radial cell file, as well as their tangential banding, are a consequence of a shared rhythmic spatio-temporal pattern of periclinal cambial divisions. With a single set of morphogen parameters required for cell determination, and using three positions for cambial cell divisions, all the cellular sequences of Secondary Phloem illustrated in the literature can be accounted for.
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Repetitive cellular patterns in the Secondary Phloem of conifer and dicot trees, and a hypothesis for their development
Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2005Co-Authors: Peter W Barlow, Jacqueline LückAbstract:Abstract The radial fusiform cell files of the Secondary Phloem of conifers and dicots are composed of different cell types – fibres, parenchyma and sieve cells (in conifers), or sieve elements plus companion cells (in dicots). These cell types are arranged in characteristic, species-specific sequences along the radii of the files. The sequences are replicated in adjacent files and this leads to tangential bands of similar cell type. Moreover, the sequences are developed repetitively so that a sequence found in one year's growth increment of Phloem is repeated in the next increment. In some species, many repetitions of the same sequence occur within one annual increment. A general hypothesis has been developed to account for the radial sequences of cell types. It is proposed that there is a gradient of a Phloem-promoting morphogen, a series of morphogen thresholds for the determination of each Phloem cell type, and a particular spatio-temporal pattern of periclinal cell division in the Phloem domain of th...
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patterned cell determination in a plant tissue the Secondary Phloem of trees
BioEssays, 2005Co-Authors: Peter W BarlowAbstract:The Secondary vascular tissues (xylem and Phloem) of woody plants originate from a vascular cambium and develop as radially oriented files of cells. The Secondary Phloem is composed of three or four cell types, which are organised into characteristic recurrent cellular sequences within the radial cell files of this tissue. There is a gradient of auxin (indole acetic acid) across both the cambium and the immediately postmitotic cells within the xylem and Phloem domains, and it is believed that this morphogen, probably in concert with other morphogenic factors, is closely associated with the determination and differentiation of the different cells types in each tissue. A hypothesis is developed that, in conjunction with the positional values conferred by the graded radial distribution of morphogen, cell divisions at particular positions within the cambium are sufficient to determine not only each of the Phloem cell types but also their recurrent pattern of differentiation within each radial cell file. BioEssays 27: 533–541, 2005. © 2005 Wiley periodicals, Inc.
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cell division systems that account for the various arrangements and types of differentiated cells within the Secondary Phloem of conifers
Plant Biosystems, 2004Co-Authors: Peter W Barlow, Jacqueline LückAbstract:There are two main types of arrangement of differentiated cells within the radial cell files of Secondary Phloem in conifer trees. In the C-type arrangement, characteristic of the Cupressaceae, fibre (F), parenchyma (P) and sieve (S) cells are arranged in recurrent groups, such as the “standard” cellular quartet (FSPS). In the P-type arrangement, characteristic of the Pinaceae, there are no fibres and one of the characteristic recurrent arrangements is the cellular sextet (PSSSSS). In addition, in both C-type and P-type arrangements, similar cell types are often organised into tangential bands. A simulation model, based on the theory of L-systems, was devised to account for the determination of these two types of regular and recurrent patterns of differentiated Phloem cells. It was based on the supposition that, in the meristematic portion of the Phloem domain, there are specific spatio-temporal patterns of periclinal cell division. When new cells are produced, those already present are displaced along th...
Thomas N. Taylor - One of the best experts on this subject based on the ideXlab platform.
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Secondary Phloem anatomy of Cycadeoidea (Bennettitales).
American journal of botany, 2007Co-Authors: Patricia E. Ryberg, Edith L. Taylor, Thomas N. TaylorAbstract:Secondary Phloem anatomy of several species of Cycadeoidea is described from trunks in the Wieland Collection, Peabody Museum of Natural History. The trunks were collected from the Lakota Formation, Lower Cretaceous, Black Hills of South Dakota. Secondary Phloem is extensively developed and consists of alternating, tangential bands of fibers and sieve elements, with rare Phloem parenchyma. Uniseriate rays, 2-22 cells high, occur between every one to three files of the axial system. Fibers are long, more than 1200 μm, approximately 26.6-34.2 μm in diameter, and have slit-like apertures on the lateral walls. Sieve elements range from 16-25 μm in diameter and are up to 500 μm long. Elliptical sieve areas appear on both end and radial walls and measure 10 μm across; minute spots, which may represent sieve pores, are present within the sieve areas. Secondary Phloem of North American Cycadeoidea is similar in organization (alternating tangential bands) and cell types (sieve cells, fibers, axial parenchyma) to that known in other extant and fossil cycadophytes and some seed ferns. The unusual pattern of cell types and thickness of Secondary Phloem is discussed in the context of plant habit, Phloem efficiency, and potential phylogenetic importance.
