Tea tree oil is a yellowish green-tinged essential oil with a fresh camphoraceous odour. It is taken from the leaves of the Melaleuca alternifolia which is native to the northeast coast of New South Wales, Australia. The oil is claimed to have beneficial cosmetic and medical properties (including antiseptic and antifungal action).
Australian Aborigines have used oil extracted from the tree's needles for hundreds of years. Currently, tea tree oil is obtained by steam distillation of the leaves. Of the over 100 compounds contained in the oil, terpinen-4-ol is responsible for most of the antimicrobial actions.
Although tea tree oil is normally extracted from Melaleuca alternifolia commercially, it can also be extracted from Melaleuca dissitiflora and Melaleuca linariifolia. Tea tree oil is defined by international standard ISO 4730 ("Oil of Melaleuca, Terpinen-4-ol type"), which specifies levels of 14 components which are needed to define the oil as "tea tree oil."