825 Ulmus americanaCommon Names: American elm Family: Ulmaceae (elm Family)
The American elm is a tall and stately vase-shaped tree. The trunk usually divides near the ground and the separate limbs grow upward, arch outward, and end in slender drooping branches. The deciduous leaves are 3-6 in (7.6-15 cm) long with prominent veins, well developed marginal teeth and asymmetrical bases. The flowers appear before the leaves in early spring. They are not showy. The fruits, called "samaras", appear a few weeks later. They are flat and papery with hairy wings around the edges. American elms usually get 60-80 ft (18.3-24.4. m) tall, but can get as tall as 120 ft (36.6 m). The elms can be recognized by their leaves which have asymmetrical, uneven bases.
Several cultivars of American elm have been named, but most are probably extinct now, victims of Dutch elm disease. 'Ascendens' has erect branches that form a tall slender crown; 'Aurea' has yellowish foliage; 'Moline' has a narrow upright habit; 'Pendula' has distinctively pendulous branches; and 'Pyramidata' has a pyramid-shaped form. 'Delaware II', 'American Liberty', and 'Princeton' are said to be at least partially resistant to Dutch elm disease.
American elm, Ulmus americana, is native to North America from Newfoundland to Florida and west to the Rocky Mountains. It was widely grown as an ornamental, shade and avenue tree, but has been killed out in most areas by Dutch elm disease. American elms can still be found in many areas in North America, but it seems only a matter of time before they all will be dead.
CultureAmerican elm is highly susceptible to Dutch elm disease. This is a fungus that grows inside living tissue, causing wilting and eventual death. It is incurable. Dutch elm disease is spread by the elm bark beetle, and the only method of control is spraying chemical insecticides to kill the beetles. Dutch elm disease is indigenous to eastern Asia where the elms there are immune or at least resistant. Dutch elm disease was first noticed in North America around 1930, and quickly spread across the continent, killing millions of American elms. It has destroyed most native elms in Europe and North America. Although live elms are still not uncommon, the disease has not run its course, and more elms die every year. It seems that elm death rates in North America have increased since the 1960's. There is considerable research going on to develop American elms or hybrids that are resistant to Dutch elm disease. So far results have been encouraging, but still no truly immune American elm strain has been found. Light: Full sun Moisture: American elm likes a moist soil and can even tolerate brief periods of flooding. Hardiness: USDA Zones 2 - 9. Propagation: Propagate American elm by seed sown as soon as it is harvested. Named cultivars may be propagated with greenwood tip cuttings taken in spring or summer.
American elm was formerly planted as a street or avenue tree, but it was not very tolerant of smoke and air pollution or of urban conditions in general, and was replaced by more tolerant street trees such as London plane (Platanus X acerfolia) and Japanese zelkova (Zelkova serrata). American elm was once extensively planted as a shade tree or large specimen in parks and estates, but Dutch elm disease has killed most of those. Where Dutch elm disease is not prevalent (Australia, New Zealand and South America), American elm, a statue of symmetrical beauty, is still an outstanding large shade tree.
The wood of American elm is strong, split resistant and durable, and has been used for furniture, paneling, boat construction and crates. The fruits are important wildlife food, especially favored by ruffed grouse, quail and partridge.
There are about 45 species of elms, all from temperate zones in Europe, Asia and North America. Six species occur in eastern North America.
American elms produce large quantities of wind-borne pollen in early spring that contribute to "hay fever" in some people.
Steve Christman 10/14/00; updated 9/29/03