The knowledge of plants used by residents of the community of Loma Alta in the Natural Protected Area of Nevado de Toluca, Mexico, to treat respiratory illnesses is documented. Medicinal plants, methods of use, parts employed, preparation methods, administration ways and collection sites were identified. Sample representativeness was determined by the species' accumulation curve proposed by Balick and O'Brien and those with major cultural importance were determined with the Informant Consensus and Friedman Index (FL). 13 taxa are registered: Arceuthobium vaginatum, Barkleyanthus salicifolius, Calendula officinalis, Cosmos parviflorus, Didymaea alsinoides, Eucalyptus globulus, Gnaphalium canescens, Matricaria recutita, Pelargonium x domesticum, Pinus hartwegii, Plantago australis, Simsia amplexicaulis, and Symphoricarpos microphyllus. Asteraceae is the best represented family (6 spp.). The main respiratory affections treated are cough, flu, colds, tonsillitis, and phlegm accumulation. Plants with a major importance according to the cultural importance index are G. canescens (FL = 82), E. globulus (FL = 80) and M. recutita (FL = 50). These species are highly accessible to users and they are available with a relative frequency in altered zones in the surroundings of the area of study as well as in local markets. It is concluded that the combined use of plants with pharmaceutical products is one of the main factors that potentially affect knowledge regarding medicinal flora.
