Intraspecific variability of wild thyme (Thymus serpyllum L.) occurring in Poland

The purpose of the study was to assess the variability between 16 wild thyme populations introduced into ex situ conditions, in terms of morphological traits and chemical profiles. The observations were carried out on 2-year-old plants. Total content of essential oil and phenolic compounds (flavonoids, phenolic acids and tannins) was determined according to Polish Pharmacopoeia 6th. The composition of essential oil was carried out by GC/MS and GC/FID. Populations differed in respect of examined traits, i.e.: plant's height (from 50 to 90 mm), plant diameter (from 21.3 to 53.0 cm), length of stems (from 8.1 to 20.5 cm). Fresh mass of herb per plant ranged from 36.0 to 307.0 g, while dry mass from 15.63 to 73.11 g (CV 55.0 and 47.5%, respectively). Total content of essential oil varied from 0.23 to 0.97%. Three chemotypes were distinguished within investigated populations: geranyl acetate + beta-terpineol + beta-myrcene, geranyl acetate + beta-terpineol + borneol and pure linalool type. The total content of phenolic compounds ranged, as following: flavonoids (0.17-0.26%), tannins (0.57-1.32%), phenolic acids (0.28-0.61%). To sum up, investigated populations differed significantly in respect of developmental features as well as content and composition of identified compounds. Obtained results may be used in future works on selection and breeding of wild thyme, providing a high-quality raw material characterized by specific chemical composition and pharmacological activity.