Medicinal plants are an important aspect of local medical systems. The composition of a medicinal plant collection is influenced by cultural and environmental factors. Additionally, the functionality of a local medical system can be threatened by the replacement of native species with exotic ones, as well as by cultural factors such as the erosion of knowledge. The objectives of this study are: 1) examine the composition of the medicinal plant collection of two rural communities settled in the caatinga (savanna-like vegetation) of the state of Pernambuco (Brazil); 2) observe the role of exotic plants in the local medical systems; and 3) identify the profile of the species utilized according to the Utilitarian Redundancy Model. Similarities were observed between the medicinal floras of the communities studied, emphasizing the importance of the surrounding biome within the possibilities of species selection, although exotic species appear to contribute by increasing the diversity of species considered in the communities to be medicinal. The native species act broadly among the body systems recognized in the two communities, whereas exotic species act in specific body systems, for which there are few associated native species.

Esta nota científica objetivou testar o poder da hipótese da aparência para explicar a seleção de plantas medicinais em uma comunidade rural assentada na Caatinga do Estado de Pernambuco. Foram estudadas 61 plantas, consideradas medicinais pelas pessoas, que passaram por uma triagem fitoquímica para atender as premissas da hipótese. Concluiu-se que a "aparência" não explica a totalidade dos achados reportados neste trabalho.

This scientific note examines the ability of the apparency hypothesis to explain the selection of medicinal plants by members of a rural community located in the Caatinga dryland region of Pernambuco state. A total of 61 plants considered to be medicinal were examined phytochemically to test the premises of this hypothesis. It was concluded that apparency does not completely explain our findings.