Comparative anatomical study on argentine species of lippia known as "poleo".

Nine species belonging to the genus Lippia - Verbenaceae - are used in Argentine folk medicine. Four of them are known under the trivial name "poleo": L. turbinata Griseb., L. fissicalyx Troncoso, L. integrifolia (Griseb.) Hieron. and L. grisebachiana Mold. Mainly, their leaves are employed as digestive, stomaquique, tonic, nervine, diuretic and emenagoge. The Argentine Pharmacopoeia includes a monography of "poleo", restricted only to L. turbinata and L. fissicalyx . Because of possible sustitutions of the official species with the others, due to their common names, an anatomical comparative research was performed to determine which features could provide a start point to distinguish them. The results of this survey show that hairs not only are different in size and shape within the species but also in their density. Thus, they are a useful feature to identify each one. When transverse sections are compared, some differences in their shape, the number of palisade layers and the presence of fibers can provide other start points to distinguish these species among them.