anatomical structure study of aerial organs in four populations of urtica dioica l.

urtica dioica l. is an iranian native pharmacological plant for which little attention has been paid to the anatomical structure. medical applications of this plant include diabetes therapy, digestive improvement, anemia and kidney disease therapy. because climatic conditions can affect the anatomical structure which in turn affects pharmacological compositions, research on the anatomy of this plant is needed. in this research, plant samples were collected from populations near the cities of brojerd, mashad, ghazvin, and ramsar. cross sections, were made from stem, leaf, and petiole at the second internodes, and stained using double staining methods. differences between stem, leaf, and petiole tissues confirmed that climatic factors produced differences among the populations in anatomical structure of aerial organs.  noted differences included: 1- number and diameter of vascular bundles with five vascular bundles in ghazvin population, five to seven vascular bundles in the brojerd population, and four vascular bundles in populations in mashad and ramsar. the mashad and ramsar populations differed in diameter. 2- protective tissue and thickness of the cuticle of plants from ghazvin had more tissues because of lower thermal mean and mountain region. 3- differences in petiole diameter with the largest petiole diameter in the mashad population and the smallest petiole diameter in the ramsar population. these observed differences in anatomy confirmed the effect of climate on differentiation in anatomical structure in urtica dioica l.