By Gilles Figuérédo, Patrick Cabassu, Jean-Claude Chalchat and Bernard Pasquier

Abstract: Abstract: The essential oils of Origanum elongatum Emberger et Maire grown from seeds from Morocco, harvested at a natural site and in the CNPPMAI collection were analyzed by GC/MS; 67 constituents were identified, among which carvacrol predominated (> 65%), accompanied by γ-terpinene, p-cymene and linalool in small amounts. Two samples were unusually thymol-rich (≈ 15% versus < 1.5% in the other extracts, with carvacrol 55-64%). Key Word Index: Origanum elongatum, Lamiaceae, essential oil composition, thymol, carvacrol.

Introduction
Origanum elongatum Emberger et Maire belongs to Section 7 of Group C (1). It is endemic in the Moroccan Rif and northern Middle Atlas, growing in schistose soils at altitudes between 400 and 1500 m. Like Origanum compactum, this oregano is used in Morocco as a condiment. The lightness and abundance of its flowers and its long flowering time lend this species ornamental value. It appears to be one of the oregano species that grows most easily in our temperate continental climates. It is fast-growing, erect, but, unfortunately, has a limited size. Harvesting is possible in the first year, though, with low dry matter yields.

The composition of the oil of O. elongatum was studied by Velasco-Negueruela et al. (2) and Benjilali et al. (3). Velasco-Negueruela et al. characterized p-cymene, γ-terpinene (21.2-17.6%) and carvacrol (24.5-51.6%), while Benjilali et al. characterized caravacrol (36.6-76.6%) with γ-terpinene and p-cymene in the oil. Of the two other species, O. grosii Pau et Fonquer and O. floribundum Mundy in the same section, only the latter, from Algeria, has been studied chemically by Baser et al. (4); it is characterized by the presence of carvacrol (40%), γ-terpinene (12%) and p-cymene (12.5%), and up to 16% linalool.

This work reports the detailed chemical composition of the oil of O. elongatum Emberger et Maire and shows the homogeneity of the known Moroccan populations in the replicates planted at the CNPPMAI or in isolated individuals when growth was sufficiently abundant.