ELM (Ulmus, a well marked group of trees and shrubs of the elm family (Ulmaceae) . There are some 18 species widely dis tributed throughout the north temperate zone, except western North America, and found also in the mountains of the tropics.
The common European elm, U. campestris, a doubtful native of England, is found throughout a great part of Europe, north Africa and Asia Minor, whence it ranges east to north Asia and Japan. It grows in woods and hedgerows, especially in southern Britain, and on almost all soils, attaining a height of 6o to ioo, and occasionally 15o ft. The branches are numerous, spreading and often pendulous at the extremities ; the bark is rugged; the leaves ovate, rough, doubly serrate, and, as in other species of Ulmus, unequal at the base. The flowers are small, numerous, in purplish-brown tufts, and each with a fringed basal bract; the bell-shaped calyx surrounds four free stamens; the pistil bears two spreading hairy styles. They appear before the leaves in March and April. The seed-vessels are green, membra nous, one-seeded and deeply cleft. The first i o years the tree usually reaches a height of 25 to 3o ft. The wood, at first brownish white, becomes later brown with a greenish shade. It is close grained, free from knots, without apparent medullary rays, hard and tough, but will not take a polish. All parts of the trunk, includ ing the sapwood, are available in carpentry. The wood has con siderable transverse strength, does not crack when once seasoned, and is remarkably durable under water, or if kept quite dry. Elm wood is used for keels and bilge-planks, the blocks and dead-eyes of rigging, ships' pumps, coffins, wheels, furniture, carved and turned articles, and for general carpenters' work. For ornamental purposes elm trees are frequently planted, and in avenues, are highly effective. In Italy, as in ancient times, it is still customary to train the vine upon the elm.
The cork-barked elm, U. campes tris, var. suberosa, is distinguished chiefly by the thick deeply fis sured bark with which its branches are covered. There are numerous cultivated forms dif fering in size and shape of leaf, and manner of growth.
The Scotch or wych elm, U.
montana, is indigenous to Great Britain and is the common elm in the north ; it usually attains a height of about 5o ft., but among tall-growing trees may reach 120 ft. It has drooping branches, smoother and thinner bark, larger and more tapering leaves, and a far less deeply notched seed-vessel than U. campes tris. The wood is tough and hard when properly seasoned, and, being very flexible when steamed, is well adapted for boat-building. Branches of the wych elm were formerly manufactured into bows, and if forked were employed as divining-rods. The weeping elm is a variety of this species. The Dutch or sand elm is very similar to the wych elm, but produces inferior timber.
In North America there are six native species of elm, all occur ring east of the Rocky Mountains, and chiefly in the eastern United States. Of these the most widely distributed is the Ameri can or white elm (U. americana), which ranges from Newfound land to the Great Lakes and the eastern base of the Rocky Moun tains in Alberta south to Florida and Texas. This handsome tree is the largest American elm, sometimes attaining a height of zoo ft. or 120 ft., with a trunk diameter of 6 ft. to I I ft., often en larged by great buttresses at the base. It sometimes rises as a straight undivided shaft, 6o f t. to 8o ft. in height, before dividing into short spreading branches. Usually it separates at a height of 3o ft. or less into numerous upright limbs which gradually spread to form an inversely conical rounded head of long, slender, grace ful branches, frequently I oo ft. and occasionally 15o ft. in diame ter. In size, vigor and gracefulness it is fully equal to the Euro pean elm (U. campestris) and, like it, is extensively planted for shade and ornament in the northern States and adjacent Canada, especially in New England where it is a characteristic tree of streets and parks. A famous elm on Boston common, supposed to have been in existence before the settlement of Massachusetts, measured 22 ft. in circumference at the time of its destruction by a storm in 1876.
The red or slippery elm (U. fulva) is common in rich soil from Quebec to South Dakota and south to Florida and Texas. It grows 6o ft. to 7o ft. high and 1 ft. to 2 ft. in trunk diameter, with stiff branches, rough leaves and thick, fragrant, mucilaginous bark, much used in spring for chewing by small boys and employed in medicine as a demulcent. Less common are the rock or cork elm (U. racemosa) of the northern States and adjacent Canada, a large tree with corky bark, and the much smaller winged or Wahoo elm (U. alata), likewise with corky bark, found in the southern States. The southern red elm (U. serotina) and the cedar elm (U. crassi f olia), both of limited range in the southern States, differ from the other American elms in flowering in autumn instead of in spring. When of sufficient size, all American elms are of value as timber trees. The total cut of elm lumber, according to the U.S. Department of Commerce, was 8o,000,000 bd.ft. in 1936, valued at $1,958,o0o. In 1919 the cut was 194,000,00o bd.ft. and in 457,000,00o board feet.