Smallanthus sonchifolius (Poepp.) H. Rob. (yacon): microscopical identification of the leaf and stem for the pharmacognostic quality control

Abstract

Yacon is the common name of the perennial herb native to the Andes, Smallanthus sonchifolius (Poepp. ) H. Rob. (Asteraceae), cultivated in different countries as food and medicinal resource. Fleshy roots and aerial vegetative organs are often used in the treatment of diabetes. This work has aimed to study the anatomical characters of the leaf and stem, aiming to supply information for microscopic identification of the pharmacognostic quality control. The botanical material was fixed and prepared according to standard techniques of light and scanning electron microscopy. The leaf is amphistomatic, predominantly with anomocytic stomata. Non-glandular and glandular trichomes are present, being the former multicellular and uniseriate. The glandular ones are short and multicellular, with two series of cells. The mesophyll is dorsiventral and the midrib has various collateral vascular bundles in centric arrangement. The young stem has remaining epidermis, angular collenchyma, cortical parenchyma, endodermis and continuous cylinders of phloem and xylem. Secretory ducts are found in the leaf and stem. The assembled characters, such as non-glandular and glandular trichomes as well as secretory ducts and endodermis with Casparian strips, are useful for the quality control of this species.