Anatomy of the Dicotyledons: stems of land herbs used as medicinal in the Río de La Plata area (Buenos Aires, Argentina)

Abstract

Anatomy of the stems of 37 land herbs belonging to 19 families was studied. These organs are used in folk medicine in the Río de La Plata area. The objective was to get diagnostic characters to elaborate a key to distinguish the taxa from whole or fragmented stem samples. Fresh material and herbaria specimens were analyzed. Conventional histological methods and histochemical analysis to recognize starch, mucilage, lipophilic and phenolic substances were performed. The main differential traits were found in: stem outline in transection; presence and trichome types; stomata position respect to epidermal cells; presence of hypodermis or cortical fiber rings; eustele with two vascular bundles cycles; a conspicuous endodermis; presence of different crystal types and secretory structures; presence of lipophilic, mucilage and starch compounds. On the basis of the diagnostic morpho-histological characters a key was elaborated