abstract initially, the seeds of baccharis dracunculifolia were collected from populations of 10 different regions, and the cultivation experiment was carried out in an experimental area of 1,800 m2 by cultivating 100 individuals of each population. the essential oil analyses were performed on both gc-fid and gc/ms, which allowed the identification of 14 compounds. the oil yield varied from 0.31% to 0.70% among populations and season. the major oxygenated sesquiterpenes in the cultivated experiment were (e)-nerolidol (32%) and spathulenol (17%). the mean concentration in the plant of (e)-nerolidol was five times higher in march (136.53 mg/100 g of plant) than it was in july (25.03 mg/100 g of plant). the mean concentration of spathulenol increased about three fold from july (16.25 mg/100 g of plant) to april (47.50 mg/100 g of plant).