Pub Date : 2023-04-03DOI: 10.1163/22941932-bja10121
K. Frankiewicz, A. Oskolski
A recurring motif of Carlquist’s work is the identification of traits typical for primary xylem of angiosperms as a whole, but found in the secondary xylem of certain species. These traits together make up the ‘Carlquistian syndrome’. Convergent occurrence of the syndrome in plants with similar habits suggests its adaptive value. One of its components — raylessness — has received the most attention and has been regarded as the result of selection favouring stem rigidity. However, how raylessness (or the Carlquistian syndrome in general) arises ontogenetically has been little studied. Here, we report that in some plants secondary xylem resembles primary xylem of the same individual, and not that of angiosperms in general as observed by Carlquist. Based on literature and microslide surveys, we identified this prolongation of primary xylem patterns into secondary xylem in most major clades of non-monocot angiosperms, including magnoliids, asterids and rosids.
{"title":"Raylessness and paedomorphosis: losses and gains of xylem rays en route from procambium to vascular cambium","authors":"K. Frankiewicz, A. Oskolski","doi":"10.1163/22941932-bja10121","DOIUrl":"https://doi.org/10.1163/22941932-bja10121","url":null,"abstract":"\u0000A recurring motif of Carlquist’s work is the identification of traits typical for primary xylem of angiosperms as a whole, but found in the secondary xylem of certain species. These traits together make up the ‘Carlquistian syndrome’. Convergent occurrence of the syndrome in plants with similar habits suggests its adaptive value. One of its components — raylessness — has received the most attention and has been regarded as the result of selection favouring stem rigidity. However, how raylessness (or the Carlquistian syndrome in general) arises ontogenetically has been little studied. Here, we report that in some plants secondary xylem resembles primary xylem of the same individual, and not that of angiosperms in general as observed by Carlquist. Based on literature and microslide surveys, we identified this prolongation of primary xylem patterns into secondary xylem in most major clades of non-monocot angiosperms, including magnoliids, asterids and rosids.","PeriodicalId":55037,"journal":{"name":"IAWA Journal","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44753017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-31DOI: 10.1163/22941932-bja10119
Adriana Costa, A. Wiedenhoeft
The career of Sherwin J. Carlquist was marked by numerous pioneering contributions to botany and especially to ecological and evolutionary wood anatomy. He developed some of the most important modern functional hypotheses for wood, including postulating a biomechanical and fluid dynamic role for helical thickenings (HT) in seasonally dry environments. Here we endeavor to honor Carlquist’s legacy by summarizing existing observations, explicitly acknowledging that HT represent a range of non-homologous and likely functionally disparate features, and exploring HT functional hypotheses in light of data from a pantropical genus, Croton, in which HT are associated with mesic rather than xeric conditions. This is noteworthy in part because HT are commonly associated with the flora of temperate mesic areas and seasonally dry areas, particularly in non-tropical regions. Based on observations in Croton, the distribution of HT around the world, and interesting advances in fluid dynamics, we propose that diversity in this feature may serve two related functions in addition to the potential mechanical role previously articulated, namely, vessel refilling after cavitation and increased hydraulic efficiency.
Sherwin J. Carlquist的职业生涯以植物学，特别是生态和进化木材解剖学的许多开创性贡献为标志。他提出了一些关于木材最重要的现代功能假设，包括假设季节性干燥环境中螺旋增厚(HT)的生物力学和流体动力学作用。在这里，我们努力通过总结现有的观察结果来尊重卡尔奎斯特的遗产，明确承认高温代表了一系列非同源和可能的功能不同的特征，并根据来自泛热带属Croton的数据探索高温的功能假设，其中高温与mesic而不是干燥条件有关。这一点值得注意，部分原因是高温通常与温带mesic地区和季节性干旱地区的植物区系有关，特别是在非热带地区。基于在Croton的观察，全球HT的分布，以及流体动力学的有趣进展，我们提出，除了先前阐述的潜在机械作用外，该特征的多样性可能具有两个相关功能，即空化后的血管再填充和水力效率的提高。
{"title":"On the possible functions of helical thickenings in conductive cells in wood","authors":"Adriana Costa, A. Wiedenhoeft","doi":"10.1163/22941932-bja10119","DOIUrl":"https://doi.org/10.1163/22941932-bja10119","url":null,"abstract":"\u0000The career of Sherwin J. Carlquist was marked by numerous pioneering contributions to botany and especially to ecological and evolutionary wood anatomy. He developed some of the most important modern functional hypotheses for wood, including postulating a biomechanical and fluid dynamic role for helical thickenings (HT) in seasonally dry environments. Here we endeavor to honor Carlquist’s legacy by summarizing existing observations, explicitly acknowledging that HT represent a range of non-homologous and likely functionally disparate features, and exploring HT functional hypotheses in light of data from a pantropical genus, Croton, in which HT are associated with mesic rather than xeric conditions. This is noteworthy in part because HT are commonly associated with the flora of temperate mesic areas and seasonally dry areas, particularly in non-tropical regions. Based on observations in Croton, the distribution of HT around the world, and interesting advances in fluid dynamics, we propose that diversity in this feature may serve two related functions in addition to the potential mechanical role previously articulated, namely, vessel refilling after cavitation and increased hydraulic efficiency.","PeriodicalId":55037,"journal":{"name":"IAWA Journal","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42629870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-30DOI: 10.1163/22941932-bja10118
Olívia Pereira Lopes, Valentina Buttò, Sergio Rossi, B. Zanatto, G. Angeles, E. Longui
The hydraulic limitation hypothesis postulates an increase in resistance to water conductivity as trees become taller. Accordingly, we expect that the hydraulic architecture of trees shares a close relationship with the crown architecture and that anatomical traits can directly or indirectly influence hydraulic conductivity. The aim of this work was to investigate the variations in vessels, hydraulic properties and wood density of three native Brazilian tree species. We selected 40-year-old Balfourodendron riedelianum, Cariniana legalis and Handroanthus vellosoi trees and measured maximum vessel length, specific hydraulic conductivity, the percentage loss of conductivity, leaf hydraulic conductivity, and density of branches at three different positions of the crown. Variability in anatomical and hydraulic properties was mostly explained by differences between species, while small differences were related to the position of the branch along the crown-position gradient. Within the measured variables, only the maximum vessel length differed between one crown position and the other. We posit that poor differences between anatomical and hydraulic positions in the crown-position gradient could be related to sample positions within the crown, which were relatively close to each other, with branches having similar ages and diameters. Our findings demonstrate that despite growing in the same environment and having the same age, our species deploy contrasting carbon allocation and hydraulic species-specific strategies. These strategies mirror different growth performances resulting from a different trade-off between hydraulic capacity and safety.
{"title":"Hydraulic architecture of crown in three Brazilian species","authors":"Olívia Pereira Lopes, Valentina Buttò, Sergio Rossi, B. Zanatto, G. Angeles, E. Longui","doi":"10.1163/22941932-bja10118","DOIUrl":"https://doi.org/10.1163/22941932-bja10118","url":null,"abstract":"\u0000The hydraulic limitation hypothesis postulates an increase in resistance to water conductivity as trees become taller. Accordingly, we expect that the hydraulic architecture of trees shares a close relationship with the crown architecture and that anatomical traits can directly or indirectly influence hydraulic conductivity. The aim of this work was to investigate the variations in vessels, hydraulic properties and wood density of three native Brazilian tree species. We selected 40-year-old Balfourodendron riedelianum, Cariniana legalis and Handroanthus vellosoi trees and measured maximum vessel length, specific hydraulic conductivity, the percentage loss of conductivity, leaf hydraulic conductivity, and density of branches at three different positions of the crown. Variability in anatomical and hydraulic properties was mostly explained by differences between species, while small differences were related to the position of the branch along the crown-position gradient. Within the measured variables, only the maximum vessel length differed between one crown position and the other. We posit that poor differences between anatomical and hydraulic positions in the crown-position gradient could be related to sample positions within the crown, which were relatively close to each other, with branches having similar ages and diameters. Our findings demonstrate that despite growing in the same environment and having the same age, our species deploy contrasting carbon allocation and hydraulic species-specific strategies. These strategies mirror different growth performances resulting from a different trade-off between hydraulic capacity and safety.","PeriodicalId":55037,"journal":{"name":"IAWA Journal","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46857445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-27DOI: 10.1163/22941932-bja10117
Rosa Nejapa, Marcelo R. Pace
Wisteria is a legume genus composed of lianas with a disjunct distribution, occurring in temperate zones of eastern Asia and the eastern United States, being also introduced in numerous countries as an ornamental. The anatomy of the wood has been previously studied for W. sinensis and only some characteristics of the phloem have been reported for this species. Here we describe the overall wood and bark anatomy of four Wisteria species and identify diagnostic, informative anatomical features to sort them for identification purposes among the species of the genus. Samples were collected from natural, naturalized, and introduced populations and processed using traditional anatomical techniques, while a few samples were analyzed from photos available online. Wisteria species show conserved wood anatomy, even if species occur as far apart as Asia and North America. The presence of a cambial variant, vessel dimorphism, G-fibers, non-lignified axial, and ray parenchyma is common and is here interpreted as part of the lianescent syndrome. The subepidermal origin of the periderm is taxonomically informative within the subfamily. The few variable features that vary among species are the arrangement of narrow vessels: radial to dendritic pattern in the specie W. frutescens and arranged in clusters in the species distributed in Eastern Asia. Also, the ray cell composition: procumbent, square, and upright cells mixed through the body in the specie W. sinensis and procumbent to square cells in the body and upright in the margins in the species W. brachybotrys and W. frutescens.
{"title":"Wood and bark anatomy of the charismatic Wisteria vines (Leguminosae)","authors":"Rosa Nejapa, Marcelo R. Pace","doi":"10.1163/22941932-bja10117","DOIUrl":"https://doi.org/10.1163/22941932-bja10117","url":null,"abstract":"\u0000Wisteria is a legume genus composed of lianas with a disjunct distribution, occurring in temperate zones of eastern Asia and the eastern United States, being also introduced in numerous countries as an ornamental. The anatomy of the wood has been previously studied for W. sinensis and only some characteristics of the phloem have been reported for this species. Here we describe the overall wood and bark anatomy of four Wisteria species and identify diagnostic, informative anatomical features to sort them for identification purposes among the species of the genus. Samples were collected from natural, naturalized, and introduced populations and processed using traditional anatomical techniques, while a few samples were analyzed from photos available online. Wisteria species show conserved wood anatomy, even if species occur as far apart as Asia and North America. The presence of a cambial variant, vessel dimorphism, G-fibers, non-lignified axial, and ray parenchyma is common and is here interpreted as part of the lianescent syndrome. The subepidermal origin of the periderm is taxonomically informative within the subfamily. The few variable features that vary among species are the arrangement of narrow vessels: radial to dendritic pattern in the specie W. frutescens and arranged in clusters in the species distributed in Eastern Asia. Also, the ray cell composition: procumbent, square, and upright cells mixed through the body in the specie W. sinensis and procumbent to square cells in the body and upright in the margins in the species W. brachybotrys and W. frutescens.","PeriodicalId":55037,"journal":{"name":"IAWA Journal","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43107378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-10DOI: 10.1163/22941932-bja10116
Kasia Ziemińska
There is a broad diversity of imperforate tracheary elements (ITEs) — libriform fibers, fiber-tracheids, true tracheids and vasicentric/vascular tracheids — described thoroughly by Sherwin Carlquist. However, in a quantitative sense, the functional meaning of different ITE types present in the wood of vessel-bearing angiosperms remains unclear because very few structure–function studies measure ITEs’ properties. ITEs with abundant pits and wide pit borders — vascular tracheids, vasicentric tracheids, and true tracheids sensu Carlquist — have been shown to conduct water and, thanks to this conductive ability and the multitude of pits, they could also contribute to wood capacitance. A dataset of 30 temperate angiosperm tree species was reanalysed to record the presence/absence of true, vasicentric, and vascular tracheids including data on conduits15 fraction and vessel-conduit15 contact fraction (conduits15 were defined as cells resembling vessels and with a maximum lumen diameter of 15 μm. They encompassed narrow vessels, vasicentric tracheids, and vessel tails). The presence of tracheids, conduits15 fraction, and contact fraction had no effect on wood capacitance, except, per given wood volumetric lumen water content, species with true tracheids tended to have lower capacitance. These results suggest that the presence of tracheids or conduits15 properties do not limit wood capacitance, but the results do not exclude the potential role these cells may play in internal water dynamics.
{"title":"The role of imperforate tracheary elements and narrow vessels in wood capacitance of angiosperm trees","authors":"Kasia Ziemińska","doi":"10.1163/22941932-bja10116","DOIUrl":"https://doi.org/10.1163/22941932-bja10116","url":null,"abstract":"\u0000There is a broad diversity of imperforate tracheary elements (ITEs) — libriform fibers, fiber-tracheids, true tracheids and vasicentric/vascular tracheids — described thoroughly by Sherwin Carlquist. However, in a quantitative sense, the functional meaning of different ITE types present in the wood of vessel-bearing angiosperms remains unclear because very few structure–function studies measure ITEs’ properties. ITEs with abundant pits and wide pit borders — vascular tracheids, vasicentric tracheids, and true tracheids sensu Carlquist — have been shown to conduct water and, thanks to this conductive ability and the multitude of pits, they could also contribute to wood capacitance. A dataset of 30 temperate angiosperm tree species was reanalysed to record the presence/absence of true, vasicentric, and vascular tracheids including data on conduits15 fraction and vessel-conduit15 contact fraction (conduits15 were defined as cells resembling vessels and with a maximum lumen diameter of 15 μm. They encompassed narrow vessels, vasicentric tracheids, and vessel tails). The presence of tracheids, conduits15 fraction, and contact fraction had no effect on wood capacitance, except, per given wood volumetric lumen water content, species with true tracheids tended to have lower capacitance. These results suggest that the presence of tracheids or conduits15 properties do not limit wood capacitance, but the results do not exclude the potential role these cells may play in internal water dynamics.","PeriodicalId":55037,"journal":{"name":"IAWA Journal","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47351675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-02DOI: 10.1163/22941932-bja10115
A. Jacobsen, R. Pratt
Sherwin Carlquist proposed several functional interpretations for vessel diameter, including that narrow vessels were hydraulically “safe” while wide diameter vessels were more vulnerable to embolism. He applied these ideas both across species and biomes, and within xylem tissue, where function of growth ring types was inferred from vessel diameter polymorphisms (occurrence of differing vessel diameter classes within a tissue). Following on Carlquist’s ideas, we were interested in evaluating if vessel diameter polymorphism could be linked to vulnerability-to-embolism curve shape. Vulnerability curves were fit with a model that included a continuous shape term (alpha). We predicted that high variation in vessel diameter would result in lower alpha (more r-shaped) curves whereas low variation would produce higher alpha (more s-shaped) curves, with potential for intermediate curve types. Our findings support Carlquist’s functional interpretations of vessel diameter. Vessel diameter polymorphism was strongly correlated to vulnerability curve shape. Homogeneous vessel diameters were associated with more s-shaped curves. As vessel diameter polymorphism increased, alpha declined and curves became more linear. High polymorphism was associated with r-shaped curves. There was no relationship between vessel length and curve shape. Vessel diameter was strongly correlated with a common estimate of embolism resistance (P50), with wider diameter vessels associated with increased vulnerability. Vulnerability curves show enormous variety in shape and scale, and both parameters are likely critical in understanding and predicting plant function. Carlquist’s ecological anatomy data, predictions, and functional inferences will continue to be valuable as we expand our understanding of structure–function links in plant anatomy.
{"title":"Vessel diameter polymorphism determines vulnerability-to-embolism curve shape","authors":"A. Jacobsen, R. Pratt","doi":"10.1163/22941932-bja10115","DOIUrl":"https://doi.org/10.1163/22941932-bja10115","url":null,"abstract":"\u0000Sherwin Carlquist proposed several functional interpretations for vessel diameter, including that narrow vessels were hydraulically “safe” while wide diameter vessels were more vulnerable to embolism. He applied these ideas both across species and biomes, and within xylem tissue, where function of growth ring types was inferred from vessel diameter polymorphisms (occurrence of differing vessel diameter classes within a tissue). Following on Carlquist’s ideas, we were interested in evaluating if vessel diameter polymorphism could be linked to vulnerability-to-embolism curve shape. Vulnerability curves were fit with a model that included a continuous shape term (alpha). We predicted that high variation in vessel diameter would result in lower alpha (more r-shaped) curves whereas low variation would produce higher alpha (more s-shaped) curves, with potential for intermediate curve types. Our findings support Carlquist’s functional interpretations of vessel diameter. Vessel diameter polymorphism was strongly correlated to vulnerability curve shape. Homogeneous vessel diameters were associated with more s-shaped curves. As vessel diameter polymorphism increased, alpha declined and curves became more linear. High polymorphism was associated with r-shaped curves. There was no relationship between vessel length and curve shape. Vessel diameter was strongly correlated with a common estimate of embolism resistance (P50), with wider diameter vessels associated with increased vulnerability. Vulnerability curves show enormous variety in shape and scale, and both parameters are likely critical in understanding and predicting plant function. Carlquist’s ecological anatomy data, predictions, and functional inferences will continue to be valuable as we expand our understanding of structure–function links in plant anatomy.","PeriodicalId":55037,"journal":{"name":"IAWA Journal","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44663927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-23DOI: 10.1163/22941932-bja10113
F. Ewers, A. Jacobsen, J. López‐Portillo
Sherwin Carlquist established xylem vessel indices and parameters to quantify the degree of mesomorphy or xeromorphy exhibited by plants. These indices were developed as part of efforts to establish a quantitative approach to plant anatomy and the developing fields of functional and ecological anatomy. In this paper, we discuss the origin of such parameters and their merits and demerits in light of current theory and practice. Vessel diameter, vessel element length, and vessel density (vessels/mm2) remain relevant anatomical characters that describe and quantify plant function and ecology. From a functional perspective, mean diameter can be replaced by hydraulic mean diameter (dh), inspired by the Hagen–Poiseuille Law. Vessel density is presumably linked to hydraulic safety through redundancy and embolism resistance and is an essential feature of xeromorphic woods that tend to have many narrow vessels. Although vessel element length strongly correlates to xeromorphy, the reasons for the link between element length and xeromorphy are unclear. The use of anatomical indices, such as those developed and proposed by Carlquist, helped shape our understanding of plant hydraulic strategies and will continue to be important as we connect plant anatomy to plant function.
{"title":"Carlquist’s indices for vulnerability and mesomorphy of wood: are they relevant today?","authors":"F. Ewers, A. Jacobsen, J. López‐Portillo","doi":"10.1163/22941932-bja10113","DOIUrl":"https://doi.org/10.1163/22941932-bja10113","url":null,"abstract":"\u0000Sherwin Carlquist established xylem vessel indices and parameters to quantify the degree of mesomorphy or xeromorphy exhibited by plants. These indices were developed as part of efforts to establish a quantitative approach to plant anatomy and the developing fields of functional and ecological anatomy. In this paper, we discuss the origin of such parameters and their merits and demerits in light of current theory and practice. Vessel diameter, vessel element length, and vessel density (vessels/mm2) remain relevant anatomical characters that describe and quantify plant function and ecology. From a functional perspective, mean diameter can be replaced by hydraulic mean diameter (dh), inspired by the Hagen–Poiseuille Law. Vessel density is presumably linked to hydraulic safety through redundancy and embolism resistance and is an essential feature of xeromorphic woods that tend to have many narrow vessels. Although vessel element length strongly correlates to xeromorphy, the reasons for the link between element length and xeromorphy are unclear. The use of anatomical indices, such as those developed and proposed by Carlquist, helped shape our understanding of plant hydraulic strategies and will continue to be important as we connect plant anatomy to plant function.","PeriodicalId":55037,"journal":{"name":"IAWA Journal","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45880281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-13DOI: 10.1163/22941932-bja10114
Cynthia S. Jones
In 1962 Carlquist published “A Theory of Paedomorphosis in Dicotyledonous Woods” based on his observations that some species of non-tree growth forms such as stem succulents, lianas, woody herbs, and tree rosettes exhibit, in their secondary xylem, cellular characteristics more commonly associated with primary xylem. He considered the appearance of these characters an expression of protracted juvenility, and that they reflected paedomorphosis. Since then, many others have observed similar suites of traits across multiple plant lineages, as these traits also characterize secondary and insular woodiness, and have used ‘paedomorphic’ and ‘juvenile’ to describe these traits. In this essay, it is argued that the use of the term paedomorphosis should be restricted to cases where ancestor/descendant relationships are known or used in a comparative sense among closely related taxa, to retain its significance as a descriptor of an evolutionary pattern. Second, it is argued that primary growth, and therefore primary xylem, should not be considered ‘juvenile’ because it is not characteristic only of the young, pre-reproductive phases of plant growth but instead persists for the life of the plant. Because both the concepts of juvenility and paedomorphosis possess more or less well-accepted modern meanings that differ in important ways from Carlquist’s use of the terms, a different approach is suggested that focuses on the functional significance of this suit of traits, in addition to their cellular characteristics.
{"title":"‘Paedomorphosis’ and ‘juvenility’ in secondary xylem: (not such) useful constructs?","authors":"Cynthia S. Jones","doi":"10.1163/22941932-bja10114","DOIUrl":"https://doi.org/10.1163/22941932-bja10114","url":null,"abstract":"\u0000In 1962 Carlquist published “A Theory of Paedomorphosis in Dicotyledonous Woods” based on his observations that some species of non-tree growth forms such as stem succulents, lianas, woody herbs, and tree rosettes exhibit, in their secondary xylem, cellular characteristics more commonly associated with primary xylem. He considered the appearance of these characters an expression of protracted juvenility, and that they reflected paedomorphosis. Since then, many others have observed similar suites of traits across multiple plant lineages, as these traits also characterize secondary and insular woodiness, and have used ‘paedomorphic’ and ‘juvenile’ to describe these traits. In this essay, it is argued that the use of the term paedomorphosis should be restricted to cases where ancestor/descendant relationships are known or used in a comparative sense among closely related taxa, to retain its significance as a descriptor of an evolutionary pattern. Second, it is argued that primary growth, and therefore primary xylem, should not be considered ‘juvenile’ because it is not characteristic only of the young, pre-reproductive phases of plant growth but instead persists for the life of the plant. Because both the concepts of juvenility and paedomorphosis possess more or less well-accepted modern meanings that differ in important ways from Carlquist’s use of the terms, a different approach is suggested that focuses on the functional significance of this suit of traits, in addition to their cellular characteristics.","PeriodicalId":55037,"journal":{"name":"IAWA Journal","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45030682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-06DOI: 10.1163/22941932-bja10111
R. Pratt, V. Castro, A. Jacobsen
One of Sherwin Carlquist’s greatest scientific legacies is how far he advanced our understanding of the structural and functional relationships within the xylem. His research was critical in illuminating the occurrence and importance of tracheids co-occurring with vessels in the xylem of some eudicots. Here, we highlight key concepts and findings from his work on these topics, and how testing has advanced with the advent of recent methods that produce spatially explicit data on embolism formation. There are three classifications of tracheids within vessel-bearing xylem: vasicentric, true, and vascular. Carlquist viewed tracheids as critical in safely transporting water. We review the literature on tracheid function, focusing on transport safety and efficiency, and discuss how the presence of tracheids might affect other xylem traits in the context of tradeoffs. Available data indicate that Carlquist was correct in his view that tracheids are resistant to embolism, and they contribute to the safe transport of sap. Tracheids provide connections (bridges) among vessels that remain sap-filled within highly embolized vessel networks and, in this role, they promote embolism tolerance. There is still much to learn, and integrating tracheids into models of sap flow, understanding their pit traits and connections, and how they affect xylem functional tradeoffs will transform our understanding of plant sap transport. Diverse xylem structural arrangements suggest many potential ways for xylem networks to function. In species containing both vessels and tracheids, the hydraulic network appears to be able to tolerate high levels of vessel embolism within seasonal environments.
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