Foliar anatomy of medicinal land herbs growing in the Rio de La Plata region (Buenos Aires, Argentina)

Abstract

This work is part of the project “Anatomy of the vegetative organs with medicinal properties in rioplatenses Spermatophytes. I. Land herbs”. We studied leaf micrographic characteristics of 62 species belonging to 24 families. The aim was to create a dichotomous key to identify the taxa based on these leaf characteristics from both whole and fragmented plant material, and to provide a comparative table with information on quantitative parameters, important for the control of pharmacognostic quality. Mature leaves from living and herbarium specimens were studied using conventional histological techniques (peeling, epidermis print, diaphanization, cross sections). Starch, mucilage, lipophilic substances and mirosine were identified using microchemical methods. The principal differences were found in epidermal cells, distribution and stomata type, trichome types, leaf mesophyll, midrib characteristics, and stomatal and pilosity indexes. The presence of a conspicuous endodermis and the different types of crystals and internal secretory reservoirs (cells, cavities, and ducts) contributed to develop an identification key