The essential oil of the Eucalyptus plant is a complex mixture of a variety of monoterpenes and sesquiterpenes, and aromatic phenols, oxides, ethers, alcohols, esters, aldehydes, and ketones; however, the exact composition and proportion of each molecule vary with species. Among the various components of eucalyptus oil, 1,8-cineole is the most important one and, in fact, a characteristic compound of the genus Eucalyptus.