Coleogyne ramosissima Torr. (blackbrush) and Atriplex confertifolia [Torr. & Frem.] Wats. (shadscale) are cold desert shrubs from different families that often grow together in the Great Basin and the Colorado Plateau in the life zone between 800 and 2000 m elevation. Tissue and seeds from the two species were collected from several localities. Metabolic heat and carbon dioxide production rates were measured with calorespirometry on tissue from field-grown plants and on seedlings at temperatures from 5 to 35°C at 5°C intervals. Blackbrush adapts to higher temperatures earlier than does shadscale, and once it has adjusted to higher temperatures, anabolic rates keep rising with increasing temperature while for shadscale rates flatten out or drop off between 25 and 35°C. Both species are metabolically adapted to temperatures during the growth season determined by the historical rainfall pattern.