Morpho-anatomy of the leaf and stem of Eugenia pyriformis

Abstract

Eugenia pyriformis Cambess., known as uvaia, is a species of Myrtaceae native to Brazil. Its leaves are used in folk medicine to treat gout because they possess the property of inhibiting xanthine oxidase, an enzyme involved in the conversion of xanthine into uric acid. The objective of this work was to study the leaf and stem morpho-anatomy of E. pyriformis, in order to contribute to what is known about the Brazilian flora, and this medicinal plant and potential vegetal drug. Samples of mature leaves and young stems were fixed and sectioned by freehand, or embedded in glycol methacrylate and sectioned with a microtome, and then stained. In addition, microchemical tests and scanning electron microscopy were performed. The leaf is simple, symmetric, elliptic-lanceolate, with an acute apex and base, and an entire margin. The epidermis is uniseriate and coated with a moderately thick cuticle. The stomata are anomocytic and inserted at the same level as the adjacent cells. Unicellular non-glandular trichomes are abundant on the abaxial surface. The mesophyll is dorsiventral. In transverse section, the midrib is plano-convex and the petiole is circular, and both of these structures have a single bicollateral vascular bundle. In the stem, the vascular cylinder consists of external phloem, xylem and internal phloem, traversed by narrow rays. Phenolic compounds, druses and prismatic crystals of calcium oxalate are also present in the leaf and stem.