Foliar plasticity of Erythroxylum tortuosum (Erythroxylaceae) in the Cerrado: a representative neotropical genus with medicinal importance

Abstract

Erythroxylum is common in the Brazilian Cerrado. Species from this genus have ecological, pharmacological and popular medical importance. Based on this information, the aims of this study was to perform a descriptive and quantitative morphoanatomical study of Erythroxylum tortuosum leaves present in two environments: cerrado sensu stricto and campo rupestre. To carry out these studies, 24 fully developed leaves were collected and fixed from individuals across both environments. For the quantitative anatomy study, the following measurements were made: leaf area, length, width and mass; stomatal density; polar and equatorial diameter of the stomata; thickness of the leaf blade, mesophyll, epidermis and cuticles on the adaxial and abaxial surfaces; and thickness of the spongy and palisade parenchyma; specific leaf area, leaf mass area and foliar tissue density. This species shows a bald and uniseriate epidermis when viewed in cross section. Stomata are paracytic and occur only on abaxial surfaces. The mesophyll is dorsiventral type, with a dense vascular system, and the vascular bundle is collateral type. The general pattern of the veins is pinnate camptodrome and brochidodrome, with dense veins and pseudosecondary ribs. Significant differences were found for almost all analysed variables, suggesting that different environmental conditions may influence plant development.