Rose in greenhouses, and in warmer countries they may also be grown under cover in order to ensure that the flowers are not damaged by weather and that pest and disease control can be carried out effectively. Significant quantities are grown in some tropical countries, and these are shipped by air to markets across the world. Some kind of roses are artificially coloured using dyed water, like rainbow roses. Rose perfumes are made from rose oil (also called attar of roses), which is a mixture of volatile essential oils obtained by steam distilling the crushed petals of roses. An associated product
Cannabis flower essential oil by α-pinene and limonene which together often comprise 75% of the live plant's volatiles. However, extracted essential oils can change in composition, and the live plant, dried plant and essential oil can smell rather different. Even in "drug-type" hemp, the THC content of the essential oil was not more than 0.08%. In the essential oil of five different European hemp cultivars, the dominating terpenes were myrcene (21.1–35.0 %), α-pinene (7.2–14.6 %), α-terpinolene (7.0–16.6 %), trans-caryophyllene (12.2.–18.9 %), and α-humulene (6.1–8.7 %). The main differences between the cultivars were found in the contents of α-terpinolene and α-pinene. Other terpenoids present only