Anatomical study on Origanum vulgare subsp. viridulum (Lamiaceae)

Abstract

Origanum L. includes several species commonly used as spices, teas and for medicinal purposes, and is one of the most commercially important genera within the Lamiaceae family. The Origanum is found primarily in the Northern Hemisphere of the Old World, with 90% of the taxa occurring in the Mediterranean region. Turkey is an important center of the Origanum diversity with 21 species (24 taxa, 13 endemic) and 13 hybrids (12 endemic). The main purpose of this study is to investigate the anatomical features of Origanum vulgare subsp. viridulum to contribute to the systematics of Origanum. In this study, the plant specimens were collected from their natural distribution areas. The plant samples were preserved in 70% alcohol during field studies. Then, the paraffin method was used for cross sections of root, stem, and leaf. The sections were taken by microtome and stained with safranin and fast-green. In the root crosssection, there is the outermost fragmented rhizoderm, 6-7 row cortex, single-row endodermis, 7-8 row phloem, well-developed xylem layer and the pith region in the central part, respectively. Stem anatomical features are compatible with the general anatomical structure of the Lamiaceae. The leaf type is bifacial and mesophyll tissue consists of elongated palisade and spongy parenchyma cells.