Comparative Leaf Anatomy of Guettarda Species (Rubiaceae)

Abstract This study presents a comparative anatomical analysis of three Guettarda species - Guettarda pohliana, Guettarda uruguensis, and Guettarda viburnoides - commonly known as the "veludinho" group due to their velvety leaves. As members of the Rubiaceae family, these species are of taxonomic and pharmacognostic interest. The study focuses on the leaf anatomy, identifying four distinct trichome types and describing their distribution and structure. In particular, differences in stomatal positioning, the presence of druses, and sheath extensions were noted. G. pohliana and G. uruguensis exhibited a biconvex midrib shape, while G. viburnoides presented a plano-convex shape. Phenolic compounds and crystals were identified, reinforcing their taxonomic importance within the Guettardeae tribe. This research provides the first anatomical data for G. uruguensis and G. pohliana. These results contribute to the anatomical characterization of the Guettarda genus, expanding the current knowledge of these species.