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Hydraulics of Asteroxylon mackei, an early Devonian vascular plant, and the early evolution of water transport tissue in terrestrial plants

Wilson, J. P. and Fischer, W. W. (2011) Hydraulics of Asteroxylon mackei, an early Devonian vascular plant, and the early evolution of water transport tissue in terrestrial plants. Geobiology, 9 (2). pp. 121-130. ISSN 1472-4677. https://resolver.caltech.edu/CaltechAUTHORS:20110310-100110883

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Abstract

The core of plant physiology is a set of functional solutions to a tradeoff between CO_2 acquisition and water loss. To provide an important evolutionary perspective on how the earliest land plants met this tradeoff, we constructed a mathematical model (constrained geometrically with measurements of fossils) of the hydraulic resistance of Asteroxylon, an Early Devonian plant. The model results illuminate the water transport physiology of one of the earliest vascular plants. Results show that Asteroxylon’s vascular system contains cells with low hydraulic resistances; these resistances are low because cells were covered by scalariform pits, elliptical structures that permit individual cells to have large areas for water to pass fromone cell to another. Asteroxylon could move a large amount of water quickly given its large pit areas; however, this would have left these plants particularly vulnerable to damage from excessive evapotranspiration. These results highlight a repeated pattern in plant evolution, wherein the evolution of highly conductive vascular tissue precedes the appearance of adaptations to increase water transport safety. Quantitative insight into the vascular transport of Asteroxylon also allows us to reflect on the quality of CO_2 proxy estimates based on early land plant fossils. Because Asteroxylon’s vascular tissue lacked any safety features to prevent permanent damage, it probably used stomatal abundance and behavior to prevent desiccation. If correct, low stomatal frequencies in Asteroxylon reflect the need to limit evapotranspiration, rather than adaptation to high CO_2 concentrations in the atmosphere. More broadly, methods to reveal and understand water transport in extinct plants have a clear use in testing and bolstering fossil plant-based paleoclimate proxies.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1111/j.1472-4669.2010.00269.xDOIArticle
http://onlinelibrary.wiley.com/doi/10.1111/j.1472-4669.2010.00269.x/abstractPublisherArticle
ORCID:
AuthorORCID
Fischer, W. W.0000-0002-8836-3054
Additional Information:© 2011 Blackwell Publishing Ltd. Received 27 September 2010; accepted 01 December 2010. Article first published online: 19 Jan 2011. We thank Andy Knoll for helpful conversations and access to Harvard University Paleobotanical Collections material, and Mike Lamb and Seth Finnegan for valuable discussion.
Issue or Number:2
Record Number:CaltechAUTHORS:20110310-100110883
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20110310-100110883
Official Citation:Hydraulics of Asteroxylon mackei, an early Devonian vascular plant, and the early evolution of water transport tissue in terrestrial plants (pages 121–130) J. P. WILSON and W. W. FISCHER Article first published online: 19 JAN 2011 | DOI: 10.1111/j.1472-4669.2010.00269.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:22801
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:11 Mar 2011 17:33
Last Modified:03 Oct 2019 02:40

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