This is first report oil the composition of the leaf essential oils of J. communis L varieties front the Western Hemisphere. The oil of Juniperus communis var. jackii had the most distinct oil and contained moderate amounts of alpha-pinene (16.1-18.9%), delta-3-carene (17.9-28.4%) and beta-phellandrene (9.2-13.4%) along with several diterpenes including isoabienol. Juniperus communis var. charlottensis oil had a very high concentration of alpha-pinene (59.3%), with moderate amounts of beta-pinene (5.9%), delta-3-carene (3.6%) and beta-phellandrene (2.9%). The oil of J. communis var. depressa was dominated by alpha-pinene (53.9%), delta-3-carene (9.3%) and beta-pinene (5.5%) and was a little unusual in also containing citronellol, citronellyl acetate, neryl acetate and geranyl acetate with no diterpenes. The oil of J. communis var. megistocarpa possessed large amounts of alpha-pinene (58.5%), limonene (20.4%) and beta-pinene (5.0%) and, like J. communis var. depressa, its oil also contained citronellol, citronellyl acetate, neryl acetate and geranyl acetate. Putative J. communis var. saxatilis from Idaho, USA, had a high concentration of alpha-pinene (56.5%) with moderate amounts of delta-3-carene (11.5%), beta-pinene (5.4%), myrcene (4.5%) and beta-phellandrene (3.1%). The oils of these North American varieties were compared to J. communis var. communis (Sweden) and J. communis var. saxatilis (Switzerland). A survey of approximately 65 species of Juniperus revealed that isoabienol was present in eight species. X-ray, MS and (13)C-NMR were used to determine the structure of isoabienol (I) and KI and a mass spectrum is presented to aid future identification.
