Taxonomic Status of the Subspecies of Teucrium lamiifolium in Turkey: Reevaluation Based on Macro- and Micro-Morphology, Anatomy and Chemistry

English (OpenAlex)

Teucrium stachyophyllum P. H. Davis was first described as a separate species in the ‘Syrian, Lebanon and Palestine Flora’, but was reduced to a subspecies of T. lamiifolium d’Urv. in the ‘Turkish Flora’. Studies on the macro‐ and micro‐morphology as well as the anatomy of populations of T. lamiifolium subsp. stachyophyllum (P. H. Davis) Hedge & Ekim and T. lamiifolium subsp. lamiifolium in Turkey have been carried out based on herbarium specimens and field observations. The results from the anatomical studies on stems and leaves show that although the two taxa are similar in stem anatomy, they differ in terms of mesophyll thickness and occurrence of crystals in the upper epidermal cells of the leaf. Light and scanning electron microscope analyzes revealed striking differences in colour, size, sculpture and gland density between nutlets of the two taxa. Morphological studies also showed that there were important differences between the two taxa in terms of inflorescence, indumentum, and stem length and thickness. In addition, the essential oils from aerial parts of T. lamiifolium subsp. stachyophyllum and T. lamiifolium subsp. lamiifolium were isolated by steam distillation and analysed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). The major components were characterized as β‐caryophyllene (23.5–44.8%), trans‐β‐bergamotene (22.4–26.4%), germacrene D (22.2%) and (Z)‐β‐farnesene (14.0%) for subp. lamiifolium and trans‐β‐bergamotene (38.1–41.1%) and β‐caryophyllene (8.7–8.9%) for subsp. stachyophyllum , respectively. As a result of the studies, it is proposed that the taxon treated as T. lamiifolium subsp. stachyophyllum in the Turkish flora should be raised to specific rank as T. stachyophyllum.