Variability of essential oil content and composition of Origanum vulgare L. populations from a North Mediterranean Area (Liguria Region, Northern Italy)

Native populations of Origanum vulgare L. from the Liguria and Emilia regions of northern Italy were analysed for essential oil content and composition. Morphological characters suggested that the Ligurian samples belonged to the ssp. viride. The essential oil content of inflorescences ranged from less than 5 mg g(-1) in the samples from Emilia, to more than 50 mg g(-1) in some Ligurian samples, values similar to those reported for ssp. hirtum from southern Italy. Sixty-four compounds were identified in the essential oil. The samples were allotted to three main groups on the basis of oil composition: the first group had a high content of components belonging to the carvacrol/thymol biosynthetic pathway; the second was characterized by a different sesquiterpene composition and a high linalool content; and the third, including the two samples of ssp. vulgare from Emilia, was characterized by the presence of abundant sesquiterpenes. The high essential oil content of the samples studied, and the presence of some particular morphological characters suggest that the taxonomy of O. vulgare, especially in its western distribution area, needs further investigation. Linalool types, although often not considered as 'typical oregano', may be useful in promoting wider utilization of the biodiversity of this species. (C) 2000 Annals of Botany Company.