<em>Lavandula stoechas</em> subsp. <em>luisieri</em> (Rozeira) Rozeira: Variability of Chemical Composition of Essential Oil in Wild Populations

Lavandula stoechas subsp. luisieri (Rozeira) Rozeira is an aromatic shrub endemic to the south-west of the Iberian Peninsula. It is distinguished by being the only species of lavender that contains necrodol derivatives in its essential oil. This study aims to evaluate the diversity of the chemical composition of L. stoechas subsp. luisieri essential oil and how it differs from essential oils of other lavender species with which it shares its habitat and with which it can hybridize. The variability in the chemical composition of L. stoechas subsp. luisieri essential oil has been evaluated across 66 populations distributed among 14 areas in southwestern Iberian Peninsula. The main compounds present in the essential oil of Lavandula stoechas subsp. luisieri are trans-α-necrodyl acetate (20.68% ± 4.17%), 1,8-cineole (7.79% ± 7.14%) and trans-α-necrodol (8.66% ± 2.18%). Other compounds may occasionally be present in percentages greater than 6.00%, such as α-cadinol, linalool, lavandulyl acetate, fenchone and camphor. Two chemotypes have been identified in the essential oil of L. stoechas subsp. luisieri: 1) trans-α-necrodyl acetate – 1,8-cineole, and 2) trans-α-necrodyl acetate, with little or no presence of 1,8-cineole. Furthermore, the absence or very low percentage of camphor (0.16 – 7.61%) and fenchone (0.00 – 7.39%) has been confirmed as a unique characteristic of this essential oil.