Any of the more than 500 species of mostly very large trees in the genus Eucalyptus, in the myrtle family, native to Australia, New Zealand, Tasmania, and nearby islands. Many species are grown widely throughout the temperate regions of the world as shade trees or in forestry plantations. Because they grow rapidly, many species attain great height. The leaf glands of many species, especially E. salicifolia and E. globulus, contain a volatile, aromatic oil known as eucalyptus oil, used mostly in medicines. Eucalyptus wood is used extensively in Australia as fuel, and the timber is commonly used in buildings and fencing. The bark of many species is used in papermaking and tanning.

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