RESUMO
The criteria that local people use for selecting medicinal plants have been a recurrent topic in pharmacology and ethnobotany. Two of the current hypotheses regarding this phenomenon, ecological apparency and diversification, attempt to explain the inclusion of "apparent" and "non-apparent" and native and exotic taxa, respectively, in local pharmacopoeia. This study addresses the following questions: Do "apparent" and "non-apparent" medicinal plants have the same importance in local pharmacopoeia? Do "non-apparent" plants occupy more local categories of diseases than "apparent" plants? Do native and exotic medicinal plants have the same importance? Do exotic and native plants occupy different local categories of diseases? This study was conducted with householders of a community from Northeastern Brazil. Out of the 66 plant species cited, most were herbs (39 species), followed by trees and shrubs (27). Herbaceous species also occupied more local categories of diseases (51) than tree and shrub species (28). Furthermore, most of the species cited by the informants were exotic (42). Out of the 94 therapeutic applications cited in this research, 65 were treated with exotic species and 29 with native species, distributed among 13 body systems. These results support both the hypotheses of ecological apparency and diversification.