Eucalyptus, a large genus of trees belonging to the myrtle family, natives of Australia or Tasmania, a few species occurring as far north as Timor and the Moluccas. Many of them grow to an immense size, and, though rapid in growth, yield dense and valuable timber. E. amygdalina, the peppermint-tree, reaches 480 feet in height, or 150 feet more than the tallest Sequoia (q.v.), and 100 feet in girth; and other species approach these dimensions. Some are known as Iron-barks, others as Stringy-barks, whilst from their resinous exudations the whole genus are known as Gum-trees. The leaves are entire; leathery; studded with glands containing fragrant volatile oils; at first opposite and horizontal, afterwards scattered and vertical; and so varying in form at different ages as to have led to considerable confusion in the discrimination of species. The flowers are axillary, and either solitary or in clusters. The superior calyx is woody, and its upper half falls off as a cap as the flower opens, carrying the corolla with it. The stamens and the seeds are indefinite in number. As timber, E. globulus, the blue gum; E. gigantea, the stringy-bark; E. amyydalina, the peppermint tree; E. resinifera, the iron-wood; and the tewart and jarrah, E. goniocalyx and E. marginata of West Australia, seem the most valuable. E. rostrata, corymbosa, and citriodora, with other species, yield the useful astringent Australian kino (q.v.); E. Gunni, the cider-tree of Tasmania, gives a refreshing sap in spring; and E. mannifera, E. viminalis, and others, exude a saccharine manna (q.v.). Volatile oils have been distilled from the leaves of many species. That known as eucalyptus oil, used in soap-making and as an adulterant of attar of roses and oil of neroli, is now largely manufactured in Australia, mainly from E. amygdalina and I', citriodora. It is thin, pale yellow, and pungent, resembling oil of lemon. E. licemasto-ma, of Queensland, yields an oil intermediate between those of geranium and peppermint, and E. Staiyeriana 2 to 3 per cent. of one closely similar to oil of verbena. Meillee oil, that of E. oleosa, is a useful solvent for copal, resembling cajeput. Eucalyptus leaves are smoked to relieve asthma and. bronchitis; and the warm aromatic tincture prepared from them, which resembles cubebs (q.v.) in its bitter taste, though inferior to quinine in fever, is a powerful diaphoretic increasing the heart's action. Since 1854 the blue gum, E. globulus, so called from its glaucous leaves and young stems, has been successfully introduced into the Roman Campagna and elsewhere in Southern Europe - into Algeria, Egypt, Natal, India, California, and other countries with miasmatic swamps, scant supplies of firewood, or climates liable to drought. Its action on miasma is probably merely the drainage effected by its roots. It seems to thrive anywhere where the mean annual temperature is not less than 60° F., but cannot survive a temperature below 27° F.