abstract water-distilled volatile from the aerial parts of pycnocycla aucherana and p. musiformis of iranian origin was analyzed by a combination of gc and gc/ms. twenty and 23 components were identified, which approximately constituted 99.9% of the oil of p. aucherana and p. musiformis, respectively. the major constituents of p. aucherana oil were p-cymene (44.7%), -phellandrene (25.0%), -phellandrene (11.7%), spathulenol (5.6%) and guaiol (5.1%), while the main constituents of the oil of p. musiformis were thymol (53.5%), -pinene (10.7%), bornyl acetate (4.2%), limonene (3.8%) and (z)--ocimene (3.3%).