American Elm (Ulmus americana)

The American elm (Ulmus americana) is the most iconic and economically important elm in North America. Before Dutch Elm Disease arrived in 1930, it formed the canopy of nearly every street and park in the eastern half of the continent. By the 1990s, an estimated 75% of mature American elms had been killed by the disease, transforming entire urban landscapes.

Identification

Mature size: 60–100 feet tall, with crown spreads of 60–80 feet.

Form: The signature feature is a vase-shaped or fountain-like crown — a single trunk that splits into 3–6 main scaffold branches at 10–20 feet, each arching outward and upward to form an interlocking canopy. This shape made American elms ideal as street trees lining boulevards.

Leaves: 3–6 inches long, alternate, oval to oblong, with sharply double-serrated margins and an asymmetrical base (one side of the leaf attaches lower than the other on the petiole). Surface dark green and slightly rough above, paler and downy below. Yellow fall color.

Bark: Light gray with deep furrows separating broad, flat-topped ridges. Inner bark shows alternating brown and white layers when sliced (a useful field check).

Flowers and fruit: Small inconspicuous flowers in early spring before leaf-out. Distinctive papery, oval, single-seeded samaras (winged seeds) about 1/2 inch across, ripening and dropping in late spring.

Twigs: Slender, zigzag, reddish-brown.

Native range and habitat

American elm is native to most of the eastern United States and southern Canada, from Nova Scotia to Saskatchewan and south to Florida and Texas. It tolerates a wide range of soils but does best on moist, well-drained bottomland soils along rivers and floodplains. It tolerates floods, droughts, urban conditions, and a wide pH range — one reason it became the dominant urban shade tree of the late 1800s and early 1900s.

Historical significance

By 1900, American elm had become the street tree of choice across the eastern United States and Canada. Cities like New Haven, Philadelphia, Detroit, and Toronto featured continuous "cathedral elm" canopies along major boulevards. Estimates put the total population in the United States in 1930 at over 77 million trees.

After DED arrived, that population collapsed. By 1990, an estimated 75% of mature American elms had died. Cities like Detroit and Minneapolis lost virtually their entire street-tree canopies within a few decades. Some isolated mature trees (the "survivor elms") are now genetic resources for breeding programs.

Susceptibility to Dutch Elm Disease

American elm is highly susceptible to Ophiostoma novo-ulmi. Unprotected mature trees in disease-pressure areas typically die within 1–3 years of infection. The trees co-evolved with no related pathogens, so their natural defenses are minimal.

Several rare survivor genotypes have been identified and developed into modern resistant cultivars:

'Princeton' — selected pre-DED for its form, later found to be resistant

'Valley Forge' — released by the US National Arboretum in 1995, exceptional resistance

'New Harmony' — released 2007, near-immune in field trials

'Jefferson' — released 2004, narrow upright form

'St. Croix' — Minnesota survivor, released 2009

For full cultivar details, see What Cultivars Are Resistant to Dutch Elm Disease?.

Management considerations

A mature American elm should be assumed susceptible unless it is a documented resistant cultivar. Preventive fungicide injection programs can protect high-value specimens for decades — see Treatment & Management.

For new plantings, choose a documented resistant cultivar. Pure unselected American elm is no longer a sound landscape choice in DED areas.

Other uses

American elm wood is hard, heavy, and interlocked-grained, historically used for wagon-wheel hubs, barrel staves, and chair seats. The interlocked grain makes it resist splitting but also difficult to work — it's now mostly a niche wood for specialty uses. The bark was used by Indigenous peoples for canoes, containers, and shelter coverings.

Related pages

Elm Species: A Complete Guide

How to Identify an Elm Tree

What Cultivars Are Resistant to Dutch Elm Disease?

Will Dutch Elm Disease Make Elms Extinct?

Where Did Dutch Elm Disease Come From?

References

Bey, C. F. (1990). "Ulmus americana L., American elm." In Silvics of North America: Hardwoods (Agric. Handb. 654), USDA Forest Service.

Townsend, A. M., Bentz, S. E., & Douglass, L. W. (2005). "Evaluation of 19 American elm clones for tolerance to Dutch elm disease." Journal of Environmental Horticulture, 23(1), 21–24.

Slavicek, J. M., et al. (2009). "Genetic improvement of American elm for restoration of riparian and floodplain ecosystems." Native Plants Journal, 10(2), 78–84.