Chemosystematics of Juniperus: Effects of leaf drying on the essential oil composition of Juniperus pinchotii

A bulk collection of terminal branchlets was made from J. pinchotii and subjected to drying at 42oC (24 hrs), then stored for up to 24 mos. at 22oC (room temperature, RT). The oils were distilled and analyzed from fresh, 0.5, 1, 2, 4, 8, 16, and 24 mos. storage at RT. The oil yields showed a slight decline initially, but remained fairly constant. Camphor, camphene hydrate and citronellal declined (mg/g dry foliage) in fresh vs. 0.5 mo. samples. Borneol increased during storage (on a mg/g basis). This may be due to the loss of acetate by bornyl acetate and/ or oxidation of terpenes to produce borneol. Overall, most of the changes occurred between the fresh and 0.5 mo. samples. It appears one can use the oils from dried leaves of Juniperus pinchotii for geographical studies, but mixing fresh and dried leaf samples may present a problem for this taxon. Published on-line: www.phytologia.org Phytologia 95(1): 10-17 (Feb. 1, 2013).