Anatomia e histoquímica de Baccharis subgênero Coridifoliae (Asteraceae)

Abstract

Baccharis is one of the most representative genera of Asteraceae, comprising 440 species originally distributed in the American continent. Many species of this genus are known in traditional medicine as “carquejas” or “vassouras”, and popularly used for the same therapeutic purposes, mainly in tea form, acting as anti-inflammatory, digestive, diuretic and antidiabetic. Several species of Baccharis are often morphologically similar, which makes taxonomic identification difficult. Thus, the morphoanatomy of species of the genus have been investigated, seeking to identify new characters to solve doubts resulting from difficulty of identification. In that sense, this work aims to analyze the leaf and stem anatomy of ten Baccharis species of the subgenus Coridifoliae: B. albilanosa, B. artemisioides, B. bicolor, B. coridifolia, B. erigeroides, B. napaea, B. pluricapitulata, B. ochracea B. scabrifolia and B. suberectifolia, in order to provide taxonomic and pharmacobotanical subsidies, contributing to the characterization of this taxon species and the quality control of herbals. Light and scanning electron microscopy techniques were used, as well as histochemical analyzes to identify secondary metabolites in the studied species. As a result, several common anatomical features common to Baccharis subgen. Coridifoliae species were observed, such as leaves with revolute margin; epidermis with straight anticlinal walls; anomocytic stomata; conical non-glandular, bisseriate glandular and flagelliform glandular trichomes; secretory ducts near the phloem in the leaf and stem; a single collateral vascular bundle in the midrib; rounded/irregular stem shape and styloids, prismatics and simple bipyramidals calcium oxalate crystals. As for the Pluricephalae section, the common aspects observed were leaves with revolute margin; epidermis with straight anticlinal walls on the adaxial surface; anomocytic stomata; bisseriate glandular and flagelliform glandular trichomes; secretory ducts; stem with flagelliform glandular trichomes based on up to nine cells; and styloids, prismatics and simple bipyramidals crystals. Regarding the Coridifoliae section, the common characteristics found in most species were leaves with revolute margin; epidermis with straight anticlinal walls on the adaxial surface; anomocytic stomata; conical non-glandular, bisseriate glandular and flagelliform glandular trichomes; concave-convex midrib shape; secretory ducts; rounded stem shape and presence of styloids and prismatics crystals. The anatomical characters of the leaves and stems described, together, provide botanical subsidies that help on the identification of species, contributing to the quality control of plant and herbals, as well as providing taxonomic data for the subgen. Coridifoliae, genus Baccharis and Asteraceae family. Aditionally, this study is the first to characterize anatomically a subgenus of Baccharis. Hence, anatomy studies are necessary to characterize completely the genus, contributing with taxonomy and evolutionary studies.