Autumn essential oils of Greek oregano

The essential oils of Origanum vulgare subsp. hirtum plants collected in late autumn from six localities of three distinct geographic areas of Greece were analysed by means of GC and GC-mass spectrometry. A high quantitative variation was found in the amount of the four main components; gamma-terpinene ranged from 0.6 to 3.6% of the total essential oil, p-cymeme from 17.3 to 51.3%, thymol from 0.2 to 42.8%, and carvacrol from 1.7% to 69.6%. Plants collected from the northern part of Greece were rich in thymol (30.3-42.8% of total oil), whereas those from the southern part of the country were rich in carvacrol (57.4-69.6% of total oil). Furthermore, comparison with the essential oils obtained from plants collected from the same localities in mid-summer shows noticeable differences in the total oil content and the concentration of the four main oil components. Copyright (C) 1997 Elsevier Science Ltd.