Collier's New Encyclopedia (1921)/Elm
ELM, a genus of trees, consisting of 13 species, all natives of the N. temperate zone. Two species are common in Great Britain (U. campestris and U. montāná), with many varieties. The U. campestris, or common elm, is a fine tree, of rapid and erect growth, and yielding a tall stem, remarkable for the uniformity of its diameter throughout. The average height of a mature tree is 70 or 80 feet, but some reach 150 feet. The wood is brown, hard, of fine grain, and not apt to crack. The tree generally attains maturity in 70 or 80 years. U. montāna (the mountain or wych elm), a native of Scotland, grows to a less height than the English elm, is of slower growth, and yields a much shorter bole, but it is far bolder in its ramification and more hardy. It usually attains to the height of about 50 feet. The timber is strong and elastic, and the tree often yields large protuberances of gnarled wood, finely knotted and veined, and much esteemed for veneering. U. glabra, the smooth-leaved elm, is a species common in some parts of Great Britain. The most ornamental tree of the genus is U. pendula, the weeping elm. The American or white elm (U. americana) is abundant in the Western States, attaining its loftiest stature between lat. 42° and 46°; here it reaches the height of 100 feet, with a trunk 4 or 5 feet in diameter, rising sometimes 60 or 70 feet before it separates into a few primary limbs. The red or slippery elm (U. fulva) is found over a great extent of country in Canada, Missouri, and as far S. as lat. 31°; it attains the height of 50 or 60 feet, with a trunk 15 or 20 inches in diameter; the wood is of better quality than that of the white elm. The leaves and bark yield an abundant mucilage. The wahoo (U. alata), inhabiting from lat. 37° to Florida, Louisiana, and Arkansas, is a small tree, 30 feet high.