The American Elm (Ulmus americana), also known as the white elm, water elm, soft elm, or Florida elm, is a type of elm tree native to eastern North America. It is characterize by a vase-shaped habit, forming a broad, flat-topped or vase-like crown. The trees can live for several hundred years. It is a very hardy species that can withstand low winter temperatures. It adapts well to a range of soil types and is hardy in USDA zones 2 to 9.
In the United States, the American elm is a principal member of major forest cover trees. The species occurs naturally in an assortment of habitats, most notably rich bottomlands, floodplains, stream banks, and swampy ground, although it also often thrives on hillsides, uplands and other well-drained soils. On more elevated terrain, as in the Appalachian Mountains, it is most often found along rivers.
The American Elm has been significantly affected by Dutch Elm Disease (DED), a fungal disease spread by the elm bark beetle. This disease has led to the decline of many American Elms, especially in urban environments where they were once widely planted as street and lawn trees. Efforts have been made to develop disease-resistant cultivars, such as ‘Valley Forge’, ‘Princeton’, and ‘New Harmony’, to reintroduce this majestic tree to urban landscapes.
Identifying Physical Characteristics
- Can grow up to 80 feet tall with a trunk diameter of 2 to 5 feet.
- Older trees develop buttresses that expand their base, adding to their grandeur.
- Its bark is grayish-brown, developing deep, diamond-shaped furrows as it matures.
- Leaves are alternate, simple, and elliptic-ovate with a pointed tip and a coarsely serrated margin. They are green on the upper surface and paler green below.
- The tree’s leaves are unequal at the base, that is one side is lower than the other side of the central leaf vein.
- Flowers are small, wind-pollinated, and inconspicuous, appearing in clusters in early spring before the leaves emerge.
- The fruit is a winged samara, which helps disperse seeds by wind. It matures in spring.
Habitat and Growing Conditions
- Thrives in moist, well-drained soils but adapts to both wet and dry sites.
- Needs full sun or partial shade.
- Not particular about soil pH but prefers a neutral range.
- Tolerates urban conditions and is resistant to fire and deer browsing.
- Has a fibrous root system that makes it easy to transplant.
Interesting Facts about American Elm
- The American Elm is a symbol of resilience and has been associated with significant historical events, such as the location where George Washington took command of the American Continental Army and sites of American resistance to England.
- The American Elm was once the most popular tree for planting in cities across North America, particularly in the 19th and early 20th centuries, due to its majestic shape and excellent shade-providing qualities.
- It can live for several hundred years, with some individual trees reported to be over 650 years old.
- It is highly susceptible to Dutch Elm Disease, a fungal disease spread by the elm bark beetle that has decimated populations of American Elms across North America.
- Despite the devastation caused by Dutch Elm Disease, efforts have been made to develop disease-resistant cultivars, such as ‘Valley Forge’, ‘Princeton’, and ‘New Harmony’, to reintroduce this majestic tree to urban landscapes.
- The wood of the American Elm is very hard and has been used historically for furniture, flooring, and veneer due to its unique appearance and strength.
- It is a fast-growing tree, capable of growing 3 to 6 feet each year, and is adaptable to a wide range of soil types.
- The tree’s leaves are a food source for larvae of butterflies, including the Question Mark, Eastern Comma, Mourning cloak, and Tawny emperor.
- The bark of the American Elm was once used by Native Americans for making canoes, ropes, and other items due to its tough, fibrous nature.
- The American Elm has been used in urban environments due to its tolerance for air pollution and its ability to withstand heat and drought.
Cultivars of American Elm Tree
Princeton Elm (Ulmus americana ‘Princeton’)
- Developed in the 1920s, this cultivar is known for its excellent resistance to Dutch elm disease.
- It has a vase-shaped crown with a dense and symmetrical branching structure, making it a good choice for street plantings.
- Grows to a mature height of 70-80 feet with a spread of 50-60 feet.
Valley Forge Elm (Ulmus americana ‘Valley Forge’)
- Developed by the U.S. National Arboretum, this cultivar is considered one of the most resistant to Dutch elm disease.
- It has a more open and spreading vase-shaped crown than the ‘Princeton’ cultivar.
- Grows to a mature height of 70-80 feet with a spread of 60-70 feet.
Homestead Elm (Ulmus americana ‘Homestead’)
- This cultivar is known for its good resistance to Dutch elm disease and elm yellows, another elm disease.
- It has a vase-shaped crown with a more upright branching habit than some other cultivars.
- Grows to a mature height of 60-70 feet with a spread of 40-50 feet.
Independence Elm (Ulmus americana ‘Independence’)
- This cultivar is another good choice for areas with Dutch elm disease concerns.
- It has a vase-shaped crown with a dense branching structure.
- Grows to a mature height of 70-80 feet with a spread of 50-60 feet.
New Harmony Elm (Ulmus americana ‘New Harmony’)
- This cultivar is known for its resistance to Dutch elm disease, elm yellows, and phloem necrosis, a vascular disease of elms.
- It has a vase-shaped crown with a more upright branching habit than some other cultivars.
- Grows to a mature height of 50-60 feet with a spread of 30-40 feet.
Jacqueline Elm (Ulmus americana ‘Jacqueline’)
- This cultivar is a newer selection that shows promise for resistance to Dutch elm disease and other elm diseases.
- It has a vase-shaped crown with a dense branching structure.
- Grows to a mature height of 70-80 feet with a spread of 50-60 feet.