The Zapotec inhabitants of the Sierra de Juarez foothills in Oaxaca (Mexico) live in an area of great biological diversity. As farmers (campesinos), and occasional gatherers, hunters, and fishermen Zapotecs have a deep relationship with, and detailed knowledge of, their natural environment. Consequently, in daily subsistence and in response to illness, plants play major roles. This paper examines cultural criteria applied by the Sierra Zapotecs for selecting plants as food and/or medicine. These criteria are based on binary forms of classi¬fication. While the "hot"/"cold" dichotomy is dominant, other opposing systems exist, such as amargo/simple (bitter/neutral). Whether a plant is regarded as frio ("cold"), caliente ("hot") or (in some rare cases) templado ("temperate") depends mainly on one of the following criteria: habitat and/or the season of growth and collection, analogy in appearance to aspects of the illness being treated or features associated with well-being (doctrine of signatures), and taste and smell properties. Criteria for plant selection are not based on a single classificatory system, but are an integration of several. A comparison with ethno¬botanical data from neighboring Mixe clearly showed differences due to cultural background
