Leaf anatomy of Rubiaceae species in a semiarid area of Brazil

Abstract Considering the importance of anatomical characters for delimiting Rubiaceae subgroups, the difficulties involved in identifying certain taxa and the lack of studies on that group in the semiarid region, this work aimed to characterize the anatomy of the leaves of 15 species belonging to the genera: Borreria (2), Cordiera (1), Eumachia (1), Hexasepalum (4), Mitracarpus (4), Richardia (1), Staelia (1), and Tocoyena (1) collected in the Serra Branca/Raso da Catarina Environmental Protection Area (Jeremoabo-BA, Brazil), and describe useful elements supporting the group’s taxonomy. Variations were found in the shapes and contours of epidermal cells, the presence/absence and types of trichomes, mesophyll type, stomatal type and position, subsidiary cell shapes, vascular system organization, and the occurrence of collector cells and twinned stomata. The results also demonstrated that the anatomical characteristics, when considered together, represent good taxonomic tools for separating the genera and species of Rubiaceae.