Crooked Run Valley
American elm (Ulmus americana)
Ulmus americana var. floridana (Chapman) Little
Ulmus floridana Chapman
CONFIRMATION STATUS: Confirmed.
TAXONOMY: The currently accepted scientific name for American elm
is Ulmus americana L. Recognized varieties include Ulmus americana var.
americana and Ulmus americana var. floridana, which is restricted to the
coastal plains from eastern North Carolina to central Florida.
NATIVE STATUS: Native, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS: American elm is a
deciduous, fast-growing, long-lived tree which may reach 175 to 200 years
old with some as old as 300 years. In dense forest stands, American elm
may reach 100 to 200 feet (30-36 m) in height and 48 to 60 inches (122-
152 cm) in d.b.h. Heights of 80 feet (24 m) are common on medium sites
but on very wet or very dry soils, the species is often 40 to 60 feet (12-
18 m) tall at maturity. In the forest American elm often develops a clear
bole 50 to 60 feet (15-18 m) in length. Open-grown trees fork 10 to 20
feet (3-6 m) from the ground with several erect limbs forming a wide, arch-
ing crown. The alternate, double-toothed leaves are 2 to 5 inches (5-10 cm)
long and 1 to 3 inches (2.5-7.5 cm) wide. The dark gray bark is deeply fur-
rowed (9,15). The perfect flowers are borne in dense clusters of three or
four fascicles. The fruit is a samara consisting of a compressed nutlet sur-
rounded by a membranous wing. The root system of American elm varies
according to soil moisture and texture. In heavy, wet soils the root system
is widespreading, with most of the roots within 3 to 4 feet (1.0 - 1.2 m) of
the surface. On drier soils, American elm develops a deep taproot.
REGENERATION PROCESSES: American elm seed production may
begin as early as age 15 but is seldom abundant before age 40. When
mature, American elm is a prolific seed producer. Trees as old as 300 years
have been reported to bear seed. In closed stands, seed production is great-
est in the exposed tops of trees. The winged seeds are light and readily
disseminated by the wind. Although most seeds fall within 300 feet (90 m)
of the parent tree, some may be carried 0.25 mile (0.4 km) or more. In
riverbottom stands, the seeds may be carried by the water for miles.
Seeds usually germinate soon after they fall, although some seeds remain
dormant until the following spring. Germination is usually 6 to 12 days but
may extend over a period of 60 days.
American elm will reproduce fairly vigorously by stump sprouts from small
trees. Large trees 150 to 250 years old seldom sprout after cutting. Obser-
vations in undisturbed bottomlands of Minnesota suggest that replacement
of American elm may be by root suckering.
SITE CHARACTERISTICS: American elm is common on wet flats and
bottomlands but is not restricted to these sites. In the southern bottom-
land regions, it commonly occurs on terraces and flats but not in deep
swamps. At higher elevations in the Appalachians it is often limited to the
vicinity of larger streams and rarely occurs at elevations above 2,000 feet
(610 m). In the Lake States and Central States, it is found on plains and
moraine hills as well as the bottomlands and swamp margins. Along the
northeastern edge of its range, it is usually restricted to valleys along water-
ways except where it has been planted on the uplands.
American elm grows best on rich, well-drained loams. Growth is poor on
dry sands and where the summer water table is constantly high. In Michi-
gan, on loam and clay soils, growth is good when the summer water table
drops 8 to 10 feet (2.4-3.0 m) below the surface. In the South, American
elm is common on clay and silty-clay loams on bottomlands and terraces.
Growth is medium on wetter sites and good on well-drained sites. In the
arid western end of its range, American elm is restricted to silt or clay
loams in river bottoms and terraces.
SUCCESSIONAL STATUS: American elm is classed as intermediate
in tolerance among eastern hardwoods. It usually responds well to release.
Once it becomes dominant in a mixed hardwood stand, it is seldom over-
taken by the other species. It can persist for years as an intermediate but
will be replaced by tolerant hardwoods such as sugar maple (Acer sac-
charum) or beech (Fagus grandifolia) if suppressed. Although American
elm is not listed as a key species in the climax types on moist sites, it is
usually one of the associated species.
SEASONAL DEVELOPMENT: The time of flowering, seed ripening, and
seed fall varies by about 100 days between the Gulf Coast and Canada.
The flower buds swell early in February in the South and as late as May in
Canada. The trees are in flower 2 to 3 weeks before the leaves unfold. The
fruit ripens as the leaves unfold or soon afterward. The seed is dispersed as
it ripens and seed fall is usually complete by the middle of March in the
South and by the middle of June in the North.
GENERAL DISTRIBUTION: The typical variety of American elm (var.
americana) is found throughout eastern North America. Its range extends
from southern Newfoundland westward through southern Quebec and
Ontario, northwest through Manitoba into eastern Saskatchewan, then
south on the upper floodplains and protected slopes of the Dakotas. It is
found in the canyons and floodplains of northern and eastern Kansas and
in eastern Oklahoma and central Texas. American elm is common along
the Gulf Coast and east into central Florida.
American elm has suffered greatly since the introduction of Dutch elm
disease from Europe around 1930. Since then the disease has spread over
much of the United States. The disease is caused by the fungus Cerato-
cystis ulmi. Spores of this fungus are carried by American (Hylurgopinus
rufipes) and European bark beetles (Scolytus multistria) from diseased
trees to healthy trees. The beetles breed only in dead, dying, or recently
cut elm wood and winter as larvae under the bark. In the spring, adults
emerge and fly a short distance (usually less than 500 feet [150 m]) to feed
in the twig crothes or small branches in the upper parts of the living trees.
As the beetles feed, the spores are introduced into the tree and the tree be-
comes diseased. After the spores have been introduced into the tree's vas-
cular system, the xylem becomes plugged and a toxin is produced. The
trees wilt on the small branches and eventually on the whole limbs.
SKY MEADOWS DISTRIBUTION:
Tree specimens can be found on trails marked in red.
Appalachian Trail/Old Trail
South Ridge/North Ridge
Rolling Meadows/ Lost Mountain
HABITAT TYPES AND PLANT COMMUNITIES: American elm was
once a primary component of the central broad-leaved forests and bottom-
land hardwood forests of the eastern United States, generally growing in
lower elevations and close to a water source.
Common associates of American elm include balsam fir (Abies balsamea),
silver maple (Acer saccharinum), sycamore (Platanus occidentalis), pin
oak (Quercus palustris), black tupelo (Nyssa sylvatica), white ash (Fraxi-
nus americana), sweetgum (Liquidambar styraciflua), hackberry (Celtis
occidentalis), boxelder (Acer negundo), birch (Betula spp.), and hickory
IMPORTANCE AND USES: Although American elm is not considered a
preferred browse, deer, rabbits, and hares will occasionally browse the
leaves and twigs. The seeds are eaten by a number of small birds. The
flowerbud, flower, and fruit are eaten by mice, squirrels, oppossum, ruffed
grouse, northern bobwhite, and Hungarian partridge.
American elm trees provide thermal cover and nesting sites for a variety
of primary and secondary cavity nesters.
American elm can be planted for erosion protection and as a windbreak.
Its shallow and widespreading roots make it fairly windfirm.
The wood of American elm is coarse-grained, heavy, and strong. It lacks
durability, warps, and splits badly in seasoning. The wood is used in the
manufacture of boxes, baskets, crates, barrels, furniture, agricultural imple-
ments, and caskets. Elm veneer is used for furniture and decorative panels.
American elm is also used for fuel wood.
Before the advent of Dutch elm disease, American elm was prized as a
street ornamental in many cities in North America. The inner bark of
American elm was used in various decoctions by the Native Americans
in the southeastern United States.