Watertransport in plants at multiple scales: A physiological, ecological, andevolutionary appraisal
Pittermann, Jarmila .
Xylem structure-function relationships in basal tracheophytes.
The ferns are some of the most broadly distributed and diverse tracheophytic plants on Earth. They occupy habitats that range from deserts to the tropics, and they exhibit an impressive array of morphological variation, including epiphytic, arborescent and climbing habits. With origins in the Devonian, ferns are among the oldest living tracheophytes, adapting to competition from both conifers and angiosperms. The apparent success of ferns is even more remarkable given that their xylem is comprised of single-celled tracheids, and that it does not develop secondary growth. How has the structure and function of fern xylem evolved in light of the transport limitations imposed by an ancestral xylem anatomy, and importantly, are the structural and hydraulic trade-offs associated with resistance to drought-induced cavitation similar to those of higher plants? Over the past two years, research in my lab has shown that ferns employ a surprising array of traits that allow them to exhibit much higher rates of water transport than previously thought, as well as an equivalent degree of cavitation resistance as conifers and angiosperms. Given the release of fern xylem from the canopy support function, selection has acted to modify stele arrangements, conduit size and inter-conduit pitting in a manner that optimizes hydraulic performance with respect to both habitat and life-history strategy. However, ferns do not exhibit the typical suite of structure-function trade-offs associated with cavitation resistance in woody taxa, leaving us with many unresolved questions about the general physiology of these plants.
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1 - University Of California, Integrative Biology, 1156 High Street, Santa Cruz, CA, 95064, USA
macroevolution of planthydraulics
Presentation Type: Symposium or Colloquium Presentation
Location: Delaware C/Hyatt
Date: Monday, July 9th, 2012
Time: 1:15 PM