The sandalwood tree is a hemiparasitic plant. This means that it connects to the roots of other plants for its water and nutrients. It will tap into the root system of a tree or plant until that tree or plant dies, then the roots will grow until it finds another one. The sandalwood tree grows between 4 and 9 m tall. The essential oil is steam distilled from the wood. It can take up to 10 days to distill. The highest concentration of oil is in the heartwood (centre) of the tree. Because of this, older trees produce a higher yield and higher quality oil. It takes at least 15 years before a sandalwood tree is mature enough for harvest. Unlike other woods, sandalwood retains its fragrance for decades.