The eucalyptus tree is an evergreen tree that is native to Australia. In the United States, eucalyptus trees are grown indoors as houseplants, or outdoors in the Pacific Coast states. Although eucalyptus oil that is extracted from the tree has medicinal applications, the plant can be toxic to ingest in large quantities. The oil also has industrial applications as a machine oil, and may be used in perfumes because of its aromatic properties. Because of its distinct physical characteristics, eucalyptus trees are quite simple to identify.
Examine the leaves of the tree that you suspect is a eucalyptus tree. Eucalyptus leaves are long and pointed with smooth sides and a leathery texture. Under a magnifying glass, you can see glands throughout the leaves that secrete oil.
Explore the branches of the tree. Eucalyptus leaves alternate on the branches of the trees that they grow on.
Search for flowers growing from the branches. Eucalyptus flowers appear as closed cups before they blossom. Once the cups open, they do not have petals. Instead they have a number of fluffy hairs that are actually flower stamens.
Look over the flower stems for signs of fruit. Eucalyptus fruit is a small, woody capsule. It grows until it splits open, disgorging seeds.
Touch the bark of a eucalyptus tree to determine its texture. Eucalyptus bark is stringy or flaky in texture. The bark may be deciduous, and may shed its outermost layer seasonally.