Common thyme is regarded as one of the most important culinary plants. The purpose of the work was to determine the intraspecific variability of common thyme with respect to morphological and chemical characters including the content and composition of essential oil and phenolic compounds in the herb. The objects of the study were 12 clones, vegetatively multiplied from randomly selected individual plants of cultivar ‘Standard Winter’. The morphological observations and harvest of raw materials were carried out in the first year plants’ vegetation. The highest differences between clones were on fresh and dry weight of herb (CV = 0.38 and 0.36, respectively), width of leaves (CV = 0.21), and density of glandular trichomes on the abaxial surface of leaves (CV = 0.29). Examined clones were also differentiated as to the chemical features. Essential oil content (performed by hydrodestillation) and composition (by GC-MS and GC-FID) were determined and they ranged from 2.10 to 4.38 g × 100 g−1 DW. Here, thymol, γ-terpinen, and p-cymen were the dominant compounds. Clone no. 4 was distinctive as to the highest content of essential oil followed by the highest share of thymol (54.59%). The total content of phenolic acids and flavonoids (determined according to PPh 6th) also differed among clones (CV = 0.38 and 0.36, respectively). Using a validated HPLC-DAD method, the following compounds were identified: caffeic, rosmarinic, p-coumaric acids, luteolin 7-O-glucoside, naryngenin, and (−)-epicatechin. Here, rosmarinic acid followed by luteolin 7-O-glucoside were present in the highest amounts (611.47–2675.59 and 46.77–325.11 mg × 100 g−1 DW, respectively). The highest differences between clones were the contents of p-coumaric acid (CV = 0.59), luteolin 7-O-glucoside (CV = 0.50) and rosmarinic acid (CV = 0.40). Such a high range of variability can provide problems with raw material standardization. Nevertheless, it opens possibilities for breeders, whereas individual plants/clones may become valuable components for breeding.

Summary An efficient method for in vitro propagation of bastard balm by enhanced axillary shoot branching has been developed. The material to establish in vitro culture was shoot tips collected from three-year-old plants in May. The shoots obtained from initial explants were placed on MS/B5 medium containing 0.1, 0.5 or 1.0 mg/l BA with 0.01 mg/l NAA or without the auxin. The highest number of shoots per explant was obtained on the medium with 1.0 mg/l BA (3.9 shoots per explant). For the rooting of shoots ½ MS/B5 with IBA (0.25, 0.50 and 1.0 mg/l) medium was used. The medium without plant growth regulators served as a control. The best root regeneration was observed on the medium without IBA (87.1% of cuttings rooted). IBA used in the medium for shoot rooting affected the morphological traits of obtained microcuttings but not affected their weight. Irrespective of auxin concentration in this medium, obtained microcuttings acclimated in ex vitro conditions very well.

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