University of Tennessee
Forest Resources AgResearch and Education Center
Oak Ridge Forest Cumberland Forest Highland Rim Forest Arboretum

August

There is always something in bloom at the Arboretum! Use our Plants Library to plan a photo shoot or to choose one of the trails to walk. Learn more about the plants at the Arboretum by visiting our Previously Featured Plants list and our Special Seasonal Featured Plants page.


Devil's Walking Stick (Aralia spinosa)

Devil's Walking Stick Flower Devil's Walking Stick Stem As you walk to the end of Marsh Road, look to the right for a dense thicket of Devil’s Walking Stick that exhibits large terminal clusters of creamy white flowers and large compound leaves. This relatively small tree gets its name from the club-shaped branches and the “vicious” prickles along the trunk, especially at the nodes. The prickles only form during the first year of growth, and as the tree matures the older stems gradually lose their prickles.


Devil's Walking Stick Leaf Devil's Walking Stick Fruit Leaves are doubly or triply compound and may be up to 5 feet in length, with individual leaflets 2-4 inches long. The purple to black fruits mature in late summer and early fall and are eaten and dispersed by birds; the foliage may be browsed by deer. Parts of the plant were used by Native Americans and early settlers for a variety of medicinal purposes. Today it is used as an ornamental plant by gardeners. Devil’s Walking Stick is native to the southeast, but has been successfully introduced to many other parts of the eastern U.S. It belongs to the plant family Araliaceae and is in the same genus as wild sarsaparilla (Aralia nudicaulis) which is also native to our area.



Elms (Ulmus spp.)

American Elm (Ulmus americana), has a special place in the history of our country. The Liberty Tree, a large American Elm growing on the Boston Commons in the 1760’s, served as a rallying point for initial protests against the Stamp Act. These protests eventually led to the Revolutionary War.

Beginning in the 1930’s, Dutch Elm Disease, caused by a fungus, greatly reduced the populations of American Elm, once the major shade tree in towns throughout the Midwest and Eastern U.S. Although native to our region few, if any, American Elms are found at the Arboretum. Three other species of elm, however, are found along Arboretum trails.


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 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.

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.

Invasive Shrubs, Vines, and Trees

Invasive plants are non-native species that aggressively invade areas and displace native species. These plants may have been introduced by gardeners or transported from other countries by accident. Examples of invasive shrubs, vines, and trees commonly encountered at the Arboretum are shown below. These species are listed in the “Severe Threat” category by the Tennessee Exotic Pest Plant Council (tneppc.org/invasive_plants) and present management challenges as well as research opportunities. More detailed descriptions of these can be found by clicking on the individual links below.

Autumn Olive

Chinese Privet

Autumn Olive
(Eleagnus umbellata)

Chinese Privet
(Ligustrum sinense)

Multiflora Rose

Mimosa

Multiflora Rose
(Rosa multiflora)

Mimosa
(Albizia julibissin)

Japanese Honeysuckle

Oriental Bittersweet

Japanese Honeysuckle
(Lonicera japonica)

Oriental Bittersweet
(Celastrus orbiculatus)

Tree-of-Heaven

Princess Tree

Tree-of-Heaven
(Ailanthus altissima)

Princess Tree
(Paulownia tomentosa)


View a list of Previously Featured Plants

Please help us preserve our natural heritage!
No collecting of plant materials is permitted at the UT Arboretum.

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