Am. J. Bot. Join BSA Today!
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via ISI Web of Science (3)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by McCulloh, K. A.
Right arrow Articles by Sperry, J. S.
Right arrow Search for Related Content
PubMed
Right arrow Articles by McCulloh, K. A.
Right arrow Articles by Sperry, J. S.
Agricola
Right arrow Articles by McCulloh, K. A.
Right arrow Articles by Sperry, J. S.
(American Journal of Botany. 2005;92:985-989.)
© 2005 Botanical Society of America, Inc.

Physiology and Biochemistry

The evaluation of Murray's law in Psilotum nudum (Psilotaceae), an analogue of ancestral vascular plants1

Katherine A. McCulloh2 and John S. Sperry

Biology Department, University of Utah, 257 South 1400 East, Salt Lake City, Utah 84112 USA

ABSTRACT

Previous work has shown that the xylem of seed plants follows Murray's law when conduits do not provide structural support to the plant. Here, compliance with Murray's law was tested in the stem photosynthesizer Psilotum nudum, a seedless vascular plant. Psilotum nudum was chosen because the central stele does not provide structural support, which means that Murray's law is applicable, and because its simple shoot structure resembles the earliest vascular plants. Murray's law predicts that the sum of the conduit radii cubed ({Sigma}r3) should decrease in direct proportion with the volume flow rate (Q) to maximize the hydraulic conductance per unit vascular investment. Agreement with Murray's law was assessed by estimating the transpiration rate distal to a cross-section, which should determine Q under steady state conditions, and comparing that with the {Sigma}r3 of that cross-section. As predicted, regressions between the {Sigma}r3 of the cross-section and Q resulted in a linear relationship with a y-intercept that was not different from zero. Two more rigorous statistical tests were also unable to reject Murray's law. Psilotum nudum plants also increased their conductance per investment by having more conduits distally than proximally, which is more efficient hydraulically than equal or declining conduit numbers distally.

Key Words: conduit furcation number • hydraulic architecture • Murray's law • Psilotum nudum • xylem flow rate






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2005 by the Botanical Society of America, Inc.