Six ecotypes of saltcedar (Tamarix pentandra Pall.), an introduced competitive phreatophyte, were collected from Wyoming to Texas and grown at Los Lunas, New Mexico. Cladophyll epicuticular alkane and fatty acid contents were analyzed by gas-liquid chromatography. Fatty acid and alkane contents varied among the six morphologically-indistinguishable ecotypes. Alkane content patterns varied on the basis or absence of C39 and other constituents. Fatty acid contents of the C16 to C22 were different among the ecotypes. Variation was not explicable on the basis of latitude, light intensity, temperature, nutrition, or water status. Thus, the chemical taxonomy hypothesis of uniform epicuticular alkane quality within a species is not substantiated in saltcedar, and a portion of the ecotypic resistance to postemergence herbicide sprays may be due to differences in epicuticular wax quantity and quality.
