Croton L. (Crotonoideae, Euphorbiaceae) in a protected area in Northeast Brazil

Abstract

Croton is the largest genus of Crotonoideae Burmeist. (ca. 1200 species), with approximately 300 species distributed in all the phytogeographic domains in Brazil. The Chapada of Araripe Environmental Protection Area (CA-EPA) is one of the largest protected areas in northeastern Brazil and comprises many different types of vegetation. Considering the expressive representation of Croton in that northeastern region and its morphological complexity, we carried out a taxonomic study of the species occurring in the CA-EPA. The analysis of collections deposited in regional herbaria, together with field observations, revealed 18 Croton species, five of which had never been cited as occurring in the study area; seven of those taxa are endemic to the Brazilian semiarid region. Croton species were recorded in all of the vegetation types in the CA-EPA, especially in the “carrasco” and “caatinga” vegetation. The plants habits, the shapes of their stipules, extrafloral nectaries, indumenta, and staminate and pistillate sepals were important characteristics for their differentiation.