abstract the yield and composition of the essential oils from different size bracts of origanum vulgare l. ssp. virens (hoffm. et link) letswaart were measured. the bracts from the herb were separated in six different sizes by a sieving process. the essential oil content was determined by hydrodistillation for each sieving class. the smaller bracts were found to have a much higher content of oils. the three smallest classes of bracts, representing 43% of the total mass of bracts, contained 75% of the oils. moreover, with the increase of bract size a decrease in the concentration of the monoterpene hydrocarbons, p-cymene and -terpinene, was observed; in contrast an increase of the oxygenated monoterpenes, linalool, -terpineol and the phenol derivative thymol, was observed.