Folk taxonomies play a role in expanding or contracting the larger domain of ethnoecological knowledge that influences when and how cultural groups use living things. This paper demonstrates that ethnomycological classification is limited by utilitarian concerns and examines how Tzeltal Maya ethnoecological knowledge, although detailed and sophisticated, is heavily influenced by the structure of the folk classification system. Data were collected through 12 months of semi-structured and structured interviews, including freelists (n=100), mushroom collection with collaborators (n=5), open-ended interviewing (n=50), structured responses to photos (n=30), structured responses to mushroom specimens (n=15), and sentence frame substitutions (n=20). These interviews were focused on Tzeltal perceptions of mushroom ecology. Results indicate that knowledge of habit, substrate, development and seasonality of mushrooms influences mushroom hunting strategies, informs individuals when to hunt mushrooms, and serves as an indicator of how habitat changes are affecting mushroom diversity and abundance. Ethnoecological knowledge is, however, limited to those species that are recognized and classified– which in turn are limited to those species that are edible, medicinal, physiologically salient, or extremely poisonous. Ultimately these data suggest that the ethnoecological knowledge associated with ethnobiological domains is sometimes severely limited by the size, shape and structure of the folk taxonomy.