Anatomical features of Ocimum sanctum and Ocimum tenuiflorum (Lamiaceae) leaves structure

Objects of the study were Ocimum sanctum L. (holy basil) and O. tenuiflorum L. leaves, as well as the Tulsi crushed leaves. Medicinal plants are traditionally used in the world medical practice under the name Tulsi (Tulasi). The species are not included in the State Pharmacopoeia of the Russian Federation of the XIV edition, but medicinal preparations based on it enter the Russian pharmaceutical market. The article purpose was to identify the differences of O. sanctum and O. tenuiflorum leaves. Investigation of leaves micro-preparations from the surface were examined by means of microscope with a digital camera. The study determined that Tulsi leaves are characterized by diacyte type of stomatal apparatus, rounded-shaped essential oil glands more often with 4 cells, simple 2–4 cell slightly bent trichomes, glandular trichomes with single or multicellular head on a unicellular stalk. Microscopic examination of Tulasi crushed leaves revealed fragments of the epidermis; stomata with two subsidiary cells; fragments of 2–3 cell slightly bent simple trichomes; fragments of glandular trichomes with a single and multicellular head on a unicellular stalk. O. sanctum L. and O. tenuiflorum leaves were similar in structure but differed in the amount of essential oil, trichomes, oil glands and stomata. As a result of the study, for the first time, a comparative analysis of anatomical and diagnostic characters and their quantitative assessment in the leaves of two closely related basil species was established. The data obtained can be used for the identification of O. sanctum and O. tenuiflorum raw materials.