Research Plant water relations and physiological plant ecology. Research Summary Pallardy’s research interests include the physiological responses of plants to water stress and comparative water relations. Comparative studies currently under way are designed to identify several of the mechanisms by which seedlings of selected woody species and ecotypes are able to resist drought stress more effectively than others. The underlying motivation for this research is the desire to understand how selective pressures that are associated with xeric habitats influence the evolution of drought adaptations among and within species. A thorough understanding of these systems will permit generalizations concerning the means by which drought resistance of economically important plant species may be genetically improved.