Tolerances of plants to drought and salinity in the western United States

Differing capacities of plant species to tolerate drought and salinity are causative factors for presence of species and communities in various habitats. It is proposed that minimum xylem pressure potentials measured are indicative of drought tolerance and that minimum cell osmotic potentials are indicative of salt tolerance of plant species. Of 85 species measured, Nuttall saltbush (Atriplex nuttallii nuttallii) was found to be the most drought tolerant. Saltbrush (Atriplex confertifolia, A. nuttallii, A. canescens, and A. torreyi) had the lowest cell osmotic potentials measured. Although pickleweed (Allenrolfea occidentalis) grows in the saltiest soil measured, it did not have the lowest cell osmotic potential. This apparent inconsistency may be explained by the succulent characteristics of pickleweed. (USGS)