ABSTRACT Carbon dioxide and water vapor exchange at different levels of photosynthetically active radiation and temperature were measured in alpine and temperate populations of Podophyllum hexandrum Royle. The photosynthesis rate and stomatal conductance were high in alpine population irrespective of the temperature and the level of photosynthetically active radiation. Maximum and minimum rates of photosynthesis were recorded at 20° and 40°C, respectively, in both populations. The water use efficiency decreased with increasing temperatures, but was higher in the temperate population. Light compensation values were also higher in temperate plants at all temperatures. Cultivation of alpine ecotypes would appear to be easier at lower elevations as compared with temperate types.