Morphological and Phytochemical Evidence of Divergent Oregano-Type Plant Material Marketed as Origanum vulgare in Romania

The identity of oregano used as a medicinal plant and culinary spice remains controversial due to frequent confusion between Origanum vulgare L., native to the spontaneous flora of Romania (mainly subsp. vulgare), and chemically distinct oregano taxa commercially marketed under the generic name “oregano”, often associated with phenolic-rich chemotypes attributed to O. vulgare subsp. hirtum (Link) A.Terracc. The present study aimed to clarify the morphological and chemotaxonomic differences between wild Romanian populations of O. vulgare and commercially available oregano-type plant material, using authenticated O. vulgare subsp. hirtum as a comparative reference. Comparative botanical analysis was performed on wild and cultivated material, followed by thin-layer chromatography (TLC) screening and gas chromatography–mass spectrometry (GC–MS) analysis of essential oils obtained by hydrodistillation. Morphological examination revealed stable differences between wild O. vulgare subsp. vulgare and commercially sourced material in stem habit, leaf morphology, inflorescence structure, corolla coloration, and aroma. TLC screening showed the absence of phenolic derivatives in extracts from wild O. vulgare subsp. vulgare and authenticated O. vulgare subsp. hirtum, while intense thymol-related zones were detected exclusively in plants derived from commercial seeds labeled as O. vulgare. GC–MS analysis confirmed these findings, demonstrating the absence of phenolic monoterpenes in wild populations and their high abundance, particularly thymol and carvacrol, in commercial samples. These results highlight significant discrepancies between authentic wild oregano and commercially marketed plant material, emphasizing the need for rigorous botanical authentication in ethnobotanical, phytochemical, and pharmacological research.