Richness and ethnobotany of the family Euphorbiaceae in a tropical semiarid landscape of Northeastern Brazil

Euphorbiaceae stands out among angiosperms in its species richness and in the number of reported uses from ethnobotanical surveys in Brazil and other tropical countries. In Brazilian semiarid regions, species of Euphorbiaceae are among the most frequently used by rural communities, especially for medicinal purposes. The present study investigated the presence of species of Euphorbiaceae and their use by a rural population from the Araripe National Forest region, a protected area located in the Chapada do Araripe (NE Brazil). This area is considered to be of primary importance for conservation, and it is lacking in scientific research. The survey of the richness of Euphorbiaceae occurred through opportunistic plant collections and phytosociological studies between August 2011 and June 2012. We performed 153 interviews with informants who were selected based on general non-probabilistic household sampling and administered semi-structured interviews using a checklist interview that considered all the species of the family Euphorbiaceae registered in collections. We found 23 species of Euphorbiaceae, with the genus Croton (5 species) being highlighted. This study adds new occurrences of Euphorbiaceae to the region compared with the results found in previous surveys; 50% of the collected Euphorbiaceae species were considered useful, with Manihot esculenta (cassava) considered of the highest importance, with a higher utilization rate in the community ponds. The study also indicated the use of castor bean (Ricinus communis), Croton heliotropiifolius, and Jatropha gossypiifolia. The category of use that was most cited was medicinal, and most of the useful species were obtained by informants in anthropogenic areas. The richness of Euphorbiaceae in the region was representative; however, further studies should be conducted in the study area. The dynamics of Euphorbiaceae use in the studied rural population did not appear to pose a threat to native species within the conservation area.