Centrolobium tomentosum: macro-and microscopic diagnosis of the leaf and stem

ABSTRACT

Centrolobium tomentosum Guillemin ex Benth., Fabaceae, known as "araribá-rosa", is a large tree that is widespread throughout Brazil. The bark of its stem is used in folk medicine as an astringent and the leaves are employed as a poultice for wounds and bruises. The aim of this study was to contribute to the pharmacognostic quality control of this medicinal species through a macro- and microscopic diagnosis of its leaves and stems. Mature leaves and young stems were collected at Embrapa (Colombo, PR) and analyzed using standard microtechniques. The leaves are opposite or alternate, compound, imparipinnate, oblong-lanceolate and hypostomatic with paracytic stomata. The mesophyll is dorsiventral and the midrib is biconvex with a collateral vascular bundle in a circular arrangement. The petiolule is circular and its vascular system is composed of two major vascular bundles in the middle, with smaller bundles between them. The rachis has a structure similar to the petiole, and these parts have a sclerenchymatic sheath shaped in multiple arcs, which surrounds a collateral vascular bundle that is centrally located. The stem has a uniseriate epidermis with peripheral phellogen and a sclerenchymatic sheath composed of many arcs, which surrounds the phloem. The stems and leaves also have non-glandular and glandular trichomes, phenolic compounds and idioblasts made of calcium oxalate crystals. This manuscript has an important role in the morpho-anatomical diagnosis of the Brazilian flora.