Eucalyptus , a genus with about 450 species, belongs to the Myrtaceae, a family of dicots with both a tropical and a subtropical representation. Members of Myrtaceae are hardy, fast-growing evergreen trees. Subepidermal glands on their leaves and other organs contain ethereal oils, giving Eucalyptus its characteristic scent. Although the Myrtaceae family is chiefly distributed in America and Australia, the genus Eucalyptus is most concentrated in Australia. As a result, many organisms closely associated with Eucalyptus, such as the giant Australian termite, are only found within range of the plant.
Termites feed mainly on wood or other materials containing cellulose.
The protozoan lives in a termite's gut and secretes digestive enzymes that help break down the cellulose into a more usable form for the termite. The giant termites of northern Australia build hill-like nests as much as 20 feet high. They are also responsible for hollowing out the branches of Eucalyptus, creating numerous internal channels. The Aborigines first locate large termite hills and then search for potential didjeridus on Eucalyptus trees nearby. Genuine didjeridus are termite-hollowed Eucalyptus branches properly sealed and seasoned to last a lifetime.