Developmental and Structural Section
Jones, Cynthia S. , Martinez Cabrera, Hugo , Schenk , H. Jochen .
Vessel grouping: a xylem trait with functional correlates?
Among woody angiosperms, vessel grouping ranges from solitary to groups of multiple adjacent vessels. While recognized as systematically important, possible functional significance of vessel grouping has received less attention. Here we investigate whether the previously observed relationship that vessel grouping is greatest in xeric regions applies among dominant shrubs sampled from sites along transcontinental transects. We found that although total XS xylem area occupied by vessels does not differ significantly among sites, average vessel grouping differs with precipitation: vessel grouping is significantly higher in shrubs from 300-700 MAP than either lower or higher precipitation categories. As found previously, low values of vessel grouping (i.e. mostly solitary vessels) are found in woods with imperforate tracheary elements that were either tracheids or fiber-tracheids, but not libriform fibers. Higher vessel grouping is associated with greater longitudinal contact among vessel groups in our species, suggesting that higher vessel grouping may reflect greater tangential hydraulic integration in shrubs. We have suggested previously that more highly integrated hydraulic systems may be more vulnerable to embolism. A comparison of vessel grouping averages for over 80 species compiled from the literature with P50 values also compiled from the literature shows that higher values of vessel grouping are associated with higher vulnerability to embolism, but this relationship is statistically significant only in trees.
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1 - University of Connecticut, Department of Ecology and Evolutionary Biology, 75 N. Eagleville Road, Unit 3043, Storrs, CT, 06269-3043, USA
2 - University of Connecticut, Ecology and Evolutionary Biology, 75 North Eagleville Rd, U-3043, Storrs, Connecticut, 062693043, USA
3 - California State University Fullerton, Department of Biological Science, Fullerton, CA , 92834-6850 , USA
Presentation Type: Oral Paper:Papers for Sections
Location: 555B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 11:00 AM