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Elms (Ulmus spp.)

Four native species of Elms are found in East Tennessee - American Elm, Winged Elm, Slippery Elm, and Rock Elm. Beginning in the 1930's, Dutch Elm Disease, caused by a fungus, has greatly reduced the populations of these trees. American Elm, once the major shade tree in towns throughout the Midwest and East, has been virtually eliminated by this pathogen. Three species of elm found along Arboretum trails are briefly described below.

Winged Elm Winged Elm (Ulmus alata) is a relatively small tree growing to heights of 40-50 ft. Distinguishing characteristics include relatively small (1 - 3 inches long), narrow, coarsely toothed leaves and thin, corky ridges along many of its branches - the wings that are the basis for its common name. Winged elm is found along the lower parts of Cemetery Ridge Trail.

Slippery Elm Slippery Elm (Ulmus rubra) is fairly common along Old Kerr Hollow Road. The leaves are up to 7 inches long, and their upper surface is rough, feeling like sandpaper. Its common name refers to the fact that its inner bark has a very slippery, mucilaginous sap. If you scratch a leaf petiole and run a finger along the split, you can feel its slipperiness. Slippery Elm grows to heights of 60-70 ft.

Rock Elm Rock Elm (Ulmus thomasii) is present along the upper portions of Cemetery Ridge Trail and the South Forest Loop Road. Its leaves are relatively smooth in texture and 2-4 in. long. Rock Elm is also called Cork Elm because of the irregular corky wings that develop on older branches. It can grow to heights of 100 ft. Although present in East Tennessee, Rock Elm is more common in middle Tennessee. In our area, it is typically found on relatively dry, rocky sites.

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University of Tennessee - Forest Resources AgResearch and Education Center
901 South Illinois Avenue, Oak Ridge, Tennessee 37830 · Telephone: 865-483-3571 · Email: UTforest@utk.edu