The stem anatomical study on the six Stachys species

Stachys (Lamiaceae: Lamioideae) comprises of about 300 species, a largest genus with a wide distribution area in the world, is traditionally used in folk medicine. Till now, no research has been carried out regarding the stem anatomical characteristic of these species in Iran. In the present study, stem anatomy of six its species was compared. Three individuals were collected from each species, and a mature stem was selected from each individual. Stems were fixed in GAF fixative. Hand sections were stained with carmine and methylene blue dye (double stained). Results show that some anatomical properties of studied species were determined to be similar to the anatomical properties of other species of the genus Stachys. According to the anatomical comparison between the six species, shape and structure of the stem are the distinguishing features of the species. On the surface of stem, five types of trichomes were found: simple and branched nonglandular, peltate, and long and short capitate glandular trichomes. The present study shows that certain micromorphological and anatomical features of Stachys species are valuable taxonomic characters in species identification and delimitation.