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Vegetation in the high Central Andes: Bardas Blancas-Pehuenche Pass (Malargue, Mendoza, Argentina). The vegetation occurring between Bardas Blancas and Pehuenche Pass in the south of Mendoza is studied for the purpose of obtaining floristic-ecological information about plant communities. Work is carried out along an altitudinal gradient from 1420 to 2800 m a.s.l., using phytosociological method. The major plant communities yielded by analyses of comparative survey tables are described. In all, 19 plant communities are revealed, including high- and low-altitude wetlands, and 24 floristic groups characterized by diagnostic, exclusive, preferential and accompanying species. Analysis of dispersal and of hierarchical conglomerates allows confirming the close relationships of plant communities with temperature and altitude. The chorological analysis allowed to identificate two phytogeographic provinces: Patagonia and High Andes. There is a floristic-ecological relationship of phytogeographic environments with life forms. The phytosociological study revealed three vegetation belts: 1- scrubland of Neosparton ephedroides, Larrea nitida, Colliguaja integerrima and Fabiana imbricata, 2- scrubland of Adesmia volckmannii, Chuquiraga oppositifolia, Adesmia pinifolia and Adesmia obovata, and 3- steppe of Azorella monantha, Nassauvia revoluta, Empetrum rubrum and Ochetophila nana. The results may probably allow extrapolation in the north and south of the area.