Chemical polymorphism of essential oil in Thymus praecox ssp. arcticus (Lamiaceae) from Greenland

The chemistry of the essential oil of Thymus praecox Opiz ssp. arcticus (E. Durand) Jalas from Greenland was studied with the intention of comparing it with the results obtained earlier from Icelandic material. All the 17 samples collected at different localities of South–West Greenland were found to contain linalyl acetate as main component besides some sesquiterpene hydrocarbons and some oxygenated sesquiterpenes. The variable content of the sesquiterpene alcohols, nerolidol and hedycaryol in the essential oil gave reason to define four different chemotypes. The pattern of the chemotype characterizing compounds was identical with that of four of the seven chemotypes found earlier to be the most widely distributed in Iceland, namely chemotypes B, C, D, and F. No correlation between the occurrence of a certain type and special environmental conditions was found. That the essential oil chemistry and the appearance of polychemism in the Greenland Thymus plants accords so well with that of the Icelandic ones, indicates that the distance of nearly 300 km between Iceland and Greenland has not led to locally limited “chemical races” within Thymus praecox ssp. arcticus. These findings are contrary to the results obtained in some Mediterranean Thymus species.