EU'CALYP'TUS (Neo-Lat., from Gk. ea, well + KaXe7-r6s, kutypfos, covered, from KaNtIrrtiv, kalyp(ein, to cover). A genus of trees and shrubs of the natural order Myrlacem, embracing about 150 species, all lout four or five of which are natives of Australia. and Tasmania only. The few exceptional species are found from the Malay Pe ninsula southward through the East Indies. The are of striking appearance and, with related species of the same family, arc- quite character istic of the Australian forests. They have entire, leathery leaves that contain considerable volatile oil. Vim!) the young shoots of many species t he leaves are opposite, and have their upper and tower disposed as In ordinary plants.
On the older twigs the leaves are arranged alter nately upon the stem; each leaf is unsym metrical with respect to its median vein, and is so placed on the stem as to present its edge toward the sun, a protective device to prevent excessive transpiration in the hot climate in which the trees abound. Eucalyptus trees are among the most valuable plants of the Australian forests. Their timber is so varied as to meet almost every requirement, some kinds surpass ing most timbers in their great utility. On some species is noted the occurrence of considerable quantities of manna, a hard, brittle, sweet sub stance containing a form of sugar known as melitose. ,Ilany species yield a kind of kino, an astringent resin. which is used in medicine and various manufactures. Tannin is a product of the hark of others, and from the leaves an oil is distilled that has many pharmaeentieal and other uses, while from still others, called 'stringy barks,' are obtained fibres used for cordage, paper manufacture, and thatch for buildings. Eucalyp tus trees have attained a more or less deserved reputation for planting in malarial districts. They are rapid growing, and present a large leaf surface through which enormous quantities of water are given off to the air. It is probable that their beneficial action is to be attributed to their drying the soil in this way rather than to any volatile substances given off by the leaves. Whatever their action, these trees have been advantageously introduced into the Roman Cam pagna, Cape of Good Hope, the lake region of Algiers, and elsewhere, in regions formerly noted for the presence of malaria. The species first planted with this object in view was Eucalyptus Globulus (for illustration, see Plate of EDEL wEiss ) , but Eucalyptus robosta and Eucalyptus urnigera are said to be better adapted to this purpose. Among the more conspicuous of the
many timber-trees belonging to this genus is the Jarrah wood (Elecalyptus maryinata). This tree often attains a height of 80 feet without lateral branches, and at that height has a di ameter of five feet. The timber is heavy, very hard, and is especially adapted to wharf. ship, and other marine uses, it being rated very highly on account of its resistance to the attacks of the ship•orm and other borers. Its immunity is believed to be due to the large amount of astringent resin in the timber, rather than to the hardness of the wood. Eucalyptus amygda lbw is perhaps tne largest, or at least the tallest, tree known. Trees 400 feet tall are reported as rather frequent, and one measured in southeast Australia was 471 feet in height. Another had a diameter of over 20 feet at the base, which was considerably buttressed, 12 feet at 13 feet from the ground, and five feet at a height of 210 feet. The timber of this species is extensively in carpentry, as it is easily worked and does not warp readily. The tree is of rapid growth; spe cimens in southern France attained a height of 50 feet in eight years. The blue gum (Eucalyp tus Globulus) is a tree of rapid growth, attain ing a height of 350 feet, and furnishes timber equal to the best oak or ash. It is extensively used for outdoor carpentry. telegraph poles, rail way ties, etc. The tree is moderately hardy, thriving well in the south of Europe, in India, California, and Florian. It is less hardy than Eucalyptus riminalis, which latter has proved able to withstand the cooler temperatures of Cali fornia considerably north of Sacramento. Trees of this species at the Chico Forestry Station of California attained a height of 80 feet in less than 12 yea rs, and were a foot in diameter. The leaves of Eucalyptus Globules are extensitycly used for the oil they It is ob tained by distillation, is a valuable antiseptic, has a peculiar camphor-like odor, and is exten sively used in medicine and various arts. The principal constituent of the oil is eucalyptol, which is used as a diuretic, stimulant, and anti septic, being administered in certain forms of Intermittent fevers and in the dressing of wounds. The oil obtained from Eucalyptus olcosa is similar in most of its properties and uses to the oil of eajeput, which is obtained from Mela leuea Leuca dend