Biological material for these investigations comes from two distant collection sites: Suva planina (mountain in the east of Serbia) and Durmitor (mountain in Montenegro). All specimens (aerial parts of the plants) were collected in 1994 in the blooming stage and/or in the pre-blooming stage.

The results obtained show that though the yields of oils were barely influenced by plant growth stage, they varied appreciably according to the origin of the plant material: pre-blooming, Suva Planina (Serbia): 0.67%; blooming, Suva Planina (Serbia): 0.70%; blooming, Durmitor (Montenegro): 0.40%. Thirty-six components were identified. 1,8-Cineole was always predominant (60%); its concentration was lower (40%) just before blooming. Also present were germacrene D (2-15%), beta-caryophyllene (4-7%), alpha-terpineol (5-7%) and caryophyllene oxides (2-6%). In general, the chemical composition of N. nuda depended more strongly on growth stage than habitat. The only exception was caryophyllene oxide which was three times more abundant in the oil from Montenegro than in that from Serbia.