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Eurotia lanata (Pursh) Moq. (winterfat) is a boreal cold-desert subshrub, seldom more than 2 feet tall, that thrives in dry climates at cool temperatures. Diaspore collections from Matador, Saskatchewan, Canada; Pine Bluffs, Wyoming; and Sterling, Colorado, were cleaned and placed on moistened filter paper in petri dishes maintained at 0, 5, 10, 15, and 20 degreesC to study germination. Seeds germinated at all temperatures but seedlings were not acclimated to cold by germination temperature. At radicle emergence (ca. 3 mm), seeds were placed in calorimeter ampules. Heat-rate (q) was measured at a given temperature, then a vial containing NaOH solution was added to measure the rate of CO2 evolution (R-CO2) for the same tissue at the same temperature. This procedure was repeated for each of the populations at temperatures ranging from -10 to +20 degreesC. Metabolic efficiency and predicted specific growth rates were calculated from these measurements. Optimum temperature for germination, metabolism, and early seedling growth was about 10 degreesC. Stress was noted near 20 and -5 degreesC. Acclimation during germination had no effect. Differences between the three populations correlated with altitude rather than latitude.