EUCALYPTUS, a genus of trees and a few shrubs of the family Myrtacer. The species, of which there are about 300, are characterized by simple symmetrical leaves, whose edges usually turn toward the sun ; gen erally white, bell-shaped flowers, sometimes solitary, but commonly in terminal or axillary umbels near the ends of the twigs; calyx-lobes joined to form a lid, which falls off when the flower opens (from this featqre the genus is named) ; numerous stamens; and many-seeded, angular fruit-capsules. With the exception of about half a dozen species which are natives of the East Indies and the Malay Peninsula, the members of the genus are indigenous to Australasia, where the are among the most common forest trees. The various species are highly valued for planting in parks and along avenues; for the gum-resin which oozes from their trunks; for the volatile oil contained in their leaves; for the tannin obtained from their bark; and for the fibre of their inner bark. They have been widely distributed by man in warm climates, particularly in the British pos sessions. Above all they are valued for their timber, which is extensively used for wharf, ship, bridge and house building, telegraph poles, railroad ties, implements, furniture, etc. To obtain it the trees are frequently ring-barked about the beginning of the warm season so as to exhaust the sap as much as possible. After standing until the end of the dry season they are felled. Some of the species are among the largest living trees of the world. Specimens exceeding 450 feet in height and with a girth of 50 feet are occasionally reported.
Few species are hardy, but many are culti vated for ornament where they can be given shelter from cold winds, or where, like other tender ornamental plants, they can be removed to a house during the winter. In California a majority of the species thrive in the open air and are valued for their striking habits of growth, their foliage, etc. They are readily propagated from seeds sown in light, sandy soil. The seedlings should be transplanted when about four inches tall and again at rather frequent intervals, to ensure the formation of fibrous roots near the surface, thus to secure them a start when transplanted to final quarters. Transplanting should always be done in cool, moist, cloudy weather. When once established they demand no further attention than ordinary pruning and training.
Among the best-known species are the fol.
lowing: Eucalyptus globules, the blue-gum, which often exceeds 300 feet in height, has bluish or grayish smooth bark, except at the base. It is noted for its rapid growth, the un pleasantly flavored nectar of its blossoms, which is very attractive to bees, and its ability to withstand long periods of drought. It is the most frequently planted species in California, where it is also becoming naturalized by means of its seeds. It is also planted to some extent in Florida and other Gulf States, and is said to survive a temperature as low as 20° F. It is
one of the most valuable of timber trees and is one of the chief sources of oil of eucalyptus. A somewhat hardier species (E. viminalis), popu larly known as manna gum, attains about the same size, but has either dark-colored persistent bark or light-colored deciduous bark. In Cali fornia, where it also is spreading like the former, it has withstood lower temperatures and made phenomenal growths, in some instances exceeding 70 feet in height and 3 feet in girth in 12 years. It is valuable for its nectar, of which bees are very fond, but its timber is less valuable than that of the preceding species, be ing less strong. It•is frequently used for fenc ing, shingles and other purposes where strain is not expected. Perhaps the most valued is E. marginata, the jarrah tree or wood, which often attains heights exceeding 70 feet without the development of any limbs, and at that height often has a girth of 15 feet. It is not hardy. Its wood is especially valued for wharf and ship building, since it is not attacked by the teredo or shipworm. It is also highly esteemed for underground work, such as ties and telegraph poles, and, being easily worked and polished, is popular for house finishing and furniture. The largest species is probably E. amygdalina, the peppermint-tree, which is also noted for its abundant yield of oil. Its timber is not strong, but is largely used for staves, shingles, build ing, etc. E. robusta, the swamp-mahogany gum, is perhaps the species most frequently planted in swampy places. Its timber is re m....1cably durable and is used, like that of E. marginata, but is somewhat less esteemed. It is one of the finest of avenue trees, and one of the best for bees because of its abundant nectar and profuse bloom.
In medicine, oil of eucalyptus is used for its antiseptic and stimulating properties. It is very widely used in affections of the nose, mouth and bronchi, and in diseases of the bladder and urethra. It makes a very agreeable and efficient drug to add to antiseptic mouth-washes and is useful internally as an intestinal anti-fermenta tive. Trees of eucalyptus have been planted, especially in low marshy places, with a belief in their beneficial effects against malaria. It is frequently asserted that they have a direct action on malaria. By the aid they furnish in converting marshes into dry land they also help to prevent the development of mosquitoes, some forms of which are known to be the chief agents in the spread of malarial disease. (See MALARIA; VOLATILE OILS). Consult Bailey, of American Horticulture' (1914) ; Mueller, (Eucalyptographia) ; Bentham, Australiensis' (Vol. III) ; Pepper, 'Eucalyptus in Algeria and Tunisia, from an Hygienic and Climatological Point of View' (Proceedings of the American Philosophical Society, Vol.
XXXV, pp. 39-56) ; Cooper, Culture Xxxv, pp. 39-56) ; Cooper, Culture and Eucalyptus Trees.'