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

Bald Cypress (Taxodium distichum)

Bald Cypress Summer Bald Cypress Fall Bald Cypress is typically a Coastal Plains tree of the Southeast US found in swamps and along the edges of water bodies. It can also be found in drier habitats and is used as an ornamental tree in a variety of landscapes. Younger trees are pyramidal in shape and may grow up to 150 ft in height. The bases of older trees are usually buttressed. At one time, the largest tree in the Eastern US was a Bald Cypress in Weakley County known as the "Tennessee Titan." It was 175 ft tall, 13 ft in diameter, and estimated to be 1350 years old before it was struck by lightening in 1976.

Bald Cypress 'Knees' Bald Cypress Cones Bald Cypress is a deciduous gymnosperm - its green needle-like leaves occur in two ranks and turn orange to cinnamon-brown in the autumn before being shed. The globe-shaped, green female cones (0.5-1 inch in diameter) have a wrinkled surface composed of approximately 12 non-overlapping scales. At maturity, the cones turn brown and disintegrate to release the seeds.

A unique feature of Bald Cypress is the development of cypress knees, which are outgrowths from the root system that grow upward around the trees on wet sites. Although the function of these knees is unknown, it has been postulated that they facilitate gas exchange in the low oxygen environment of wetland habitats and/or provide support for the shallow-rooted trees. At the Arboretum a number of Bald Cypress trees have been planted in the Marsh Area, along Scarborough Creek, and on the hill across from the Program Shelter. The highly decay-resistant wood is used in the construction of docks, bridges, and buildings, as well as for such purposes as fence posts, boat planking, and caskets.

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American Basswood (Tilia americana)

Although not commonly seen at the Arboretum, American Basswood (also known as American Linden) is found throughout the Eastern deciduous forest. Two varieties occur in Tennessee - T. americana v. americana and T. americana v. heterophylla, the latter having a more southerly distribution and distinctive white pubescence on the undersides of its leaves. Basswood typically grows to heights of 60-80 ft tall, but may reach 100 ft or more.

American Basswood Leaves American Basswood Bark American Basswood Nutlets

It has large (4-8 in. long and 3-5 in. wide), toothed, cordate leaves. The smooth, light-colored bark of young trees becomes darker and deeply furrowed with age. In late spring, the yellowish-white flowers appear in drooping clusters subtended by a distinctive strap-like, papery bract. The fragrant flowers are very attractive to bees which produce a distinctive honey from the abundant nectar - the tree is often called "bee tree." The hard gray-brown fruits (nutlets) hang down from the papery bract and may persist into the winter months. In the fall, the nutrient-rich leaves are considered a "soil improver" in contributing calcium, magnesium, nitrogen and phosphorus to the forest soil.

The light, strong wood has many uses, including luggage, children's toys, yard sticks, furniture, musical instrument soundboards, boxes, and pulp. The inner bark is tough and fibrous and has been used as a source of fiber by Native Americans for cordage, basketry, nets, mats, fabric, clothing, and in canoe construction. Basswood is frequently planted as an ornamental and a street tree. Basswood flowers have been used for a variety of medicinal purposes, such as making a tea to ease symptoms of colds or promote sleep, and as a component of beauty products.

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American Beech (Fagus grandifolia)

American Beech Fall Leaves American Beech is found throughout the forests of eastern North America. During the winter months, it is readily identifiable along our Arboretum trails with its smooth gray bark and golden brown leaves. Beech trees are especially prevalent along the Tulip Poplar Trail, the White Pine trail, and Rockpile Lead. The alternate, serrate (saw-toothed) leaves have straight, parallel veins, each ending at the tip of a tooth on the leaf margin. The leaves frequently persist until the onset of spring when they become dull brown and are shed as the distinctive spear-shaped buds expand.

American Beech American Beech flowers in April, with the fruits (beechnuts) maturing in late summer. The spiny fruit husk (bur) contains two (sometimes three) nuts, which are eaten by many birds and mammals. Beech mast is not abundant every year, but rather it is produced at intervals of 2 to 8 years. Beech wood is used for such purposes as flooring, furniture, plywood, and railroad ties. Its high density and good burning qualities make it a favored firewood. Creosote from Beech wood has a variety of medicinal applications. American colonists used its leaves for mattress stuffing.

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River Birch (Betula nigra)

River Birch Tree A beautiful example of a River Birch cultivar ('Heritage') can be seen next to Scarborough Creek just below the Arboretum entrance. River birch is found throughout the Southeastern U.S. and ranges from southern New York and Pennsylvania, west to Indiana, and south to Texas and Florida. It is found on moist soils along stream banks, floodplains, and swampy bottomlands and can play an important role in stream bank erosion. It grows to heights of 50-75 ft and has alternate, doubly serrate (both fine and coarse teeth) leaf margins that are triangular in shape.

River Birch Bark Its attractive, scaly, beige-colored bark is a conspicuous feature that makes River Birch desirable as a landscape tree. The knotty wood has limited value for lumber but is used for pulp and as firewood. Another native birch found at the Arboretum is Sweet Birch (Betula lenta), which is present at the junction of the North Loop Rd and Backwoods Trail, as well as at other places along our trails.

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Sweet Birch (Betula lenta)

Sweer Birch Sweet Birch (also known as Black Birch or Cherry Birch) is found from Northern New England down the Appalachians to Alabama and Georgia and west to Ohio. In Tennessee, it is found primarily in the mountains and the Valley and Ridge physiographic province. Scattered individuals occur in the Arboretum's deciduous forests - two good examples can be seen at the junction of the Backwoods Trail and the North Forest Loop Road.

Sweet birch gets its common name from the wintergreen smell of its crushed leaves and twigs. Sweet Birch bark was a major source of wintergreen oil (methyl salicylate), which has a number of pharmaceutical, cosmetic, and industrial applications (flavors and fragrances) - it is now produced synthetically for commercial use. Betula lenta is also known as Black Birch because when exposed to air, the wood darkens and was used in the past as an inexpensive substitute for mahogany. The wood is used for a variety of purposes such as face veneer, plywood, cabinetry, hardwood flooring, and pulp. The sap can be fermented to make birch bark beer and vinegar. The sap and decoctions of bark have also been used for a variety of medicinal purposes to treat such conditions as colds, dysentery, and stomach ailments. The twigs purportedly make "the best wilderness toothbrushes." Sweet Birch grows to heights of 50 to 60 ft.

Sweet Birch Leaves Sweet Birch Bark It has alternate, dark green leaves, 2.5 to 6 in. long, and 1.5 to 3 in. wide. The leaves are fine toothed and have an elongated arrowhead shape. The tight dark silver-gray to black bark has horizontal rows of raised reddish brown lines (lenticels). The Virginia Roundleaf Birch found in the Wildflower Garden is considered by some botanists to be a variety of Sweet Birch.

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Virginia Roundleaf Birch (Betula uber)

Virginia Roundleaf Birch at the Arboretum Visitors Center A specimen of Virginia Roundleaf Birch, a rare native tree species, is planted in front of the Arboretum Visitor's Center. The only known native population of this tree is in Smyth County in southwest Virginia. It was first collected in 1914 and then rediscovered in 1975. The U.S. Fish and Wildlife Service listed it as an Endangered Species in 1978, and initiated an extensive recovery program involving collection of seeds which were planted in a variety of sites. The recovery plan was sufficiently successful that in 1994 the status of the species was reclassified from Endangered to Threatened. It can now be found in arboreta and botanical gardens and is available to the public for planting.

Virginia Roundleaf Birch Fruit This species has been considered a variety of Sweet Birch (Betula lenta) by some taxonomists. Sweet Birch is found along Arboretum trails (e.g., at the junction of the North Forest Loop Road Trail and the Backwoods Trail). Virginia Roundleaf Birch is a relatively small tree, reaching a height of 40 ft. The rounded leaves and dark bark have a wintergreen smell when crushed. The small cone-like fruit containing small nutlets are prominent on the tree at the Visitor's Center in the fall.

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Blackgum (Nyssa sylvatica)

Blackgum Leaves Blackgum Fruit Blackgum Bark

Blackgum (also called Black Tupelo or Sourgum), a common tree in our Arboretum forests, is found throughout the eastern U.S. Its scientific name alludes to Nyssa, the Greek water nymph, and sylvatica refers to "of the woodlands." The origin of the common name "Blackgum" is unclear but may refer to the dark blue-purple fruit. Blackgum is mainly found as a lower canopy tree, typically growing to heights of 40 to 60 ft. It has been reported as growing up to100 ft. in height and living to be over 400 years old.

The shiny, alternate leaves are from 2 to 5 in. long and usually elliptic in shape, often wider above the middle with a pointed tip. In the fall the leaves turn red, orange, yellow, or almost purple. The inconspicuous light green flowers provide a good source for honey. Blackgum is usually either predominately male or female, but frequently it has a few perfect flowers. The small, dark blue berry-like fruits (drupes) ripen in the fall. These fleshy fruits have a high content of crude fat, calcium, fiber, and phosphorus and are eaten by a wide variety of birds and other wildlife. Young sprouts are eaten by deer. Branches tend to grow at right angles to the trunk, somewhat resembling the spokes on a wheel, and older branches often droop. The blocky bark is dark and furrowed with vertical ridges.

Blackgum tends to develop cavities in the trunk and is considered to be a good den tree. In the past, the wood has been used for water pipes and ox yokes; the twigs are said to have been used for toothbrushes. The wood has many uses including gunstocks, boxes, crates, pallets, flooring, pulpwood, and railroad ties. Although Blackgum is often used as fuel, it is cross-grained and therefore somewhat difficult to split.

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Black Walnut (Juglans nigra)

Black Walnut Leaves Black Walnut Nuts Black Walnut Bark

Black Walnut, a relatively common tree at the Arboretum, is readily recognized by its large, pinnately compound leaves with 11-23 leaflets, its dark (almost black) ridged to platy bark, and its green (turning to yellow), ball-shaped fruits. It is considered a pioneer species invading fields and other open areas where it grows rapidly.

Black Walnut is an allelopathic plant, producing a chemical compound, hydrojuglone. When hydrojuglone is oxidized in air or soil, it becomes the toxic chemical juglone. This toxin (produced from the leaves, fruits, and roots) accumulates in the soil under the tree, inhibiting the growth of most other plants. A few plants, especially grasses, are unaffected by juglone and can grow under the tree canopy.

Black Walnut is a highly prized wood. Early settlers used it extensively for construction, but today it is primarily used for making furniture and gunstocks. The nuts are used in cooking, the oily husks have been used to make dyes and walnut stain, and the pulverized shells are used in oil drilling, cleaning jet engines, and for making activated charcoal.

The presence of black walnut trees at various sites around the Arboretum often indicates the location of former home sites. The fruits from these trees appear to be somewhat larger than normal, perhaps reflecting a selection by the homeowners of more vigorous cultivars.

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Bloodroot (Sanguinaria canadensis)

Bloodroot One of the harbingers of spring at the Arboretum is Bloodroot, a member of the Poppy family. It blooms in early to mid-March in the wildflower garden adjacent to the Visitors Center. It appears somewhat later along the Oak-Hickory Trail and elsewhere at the Arboretum. When it emerges, the distinctive leaves are clasping the flower stalk, but shortly after emergence, they gradually open up. Typically Bloodroot flowers have 8-12 petals with the upper ones often being somewhat larger than the lower ones - some of the plants in our wildflower garden, however, have almost twice as many petals. The common name Bloodroot is based on the red-orange sap that oozes from the underground rhizome and other parts of the plant when cut. Although the plant has been used for medicinal purposes, the alkaloids in the extracts can be toxic if ingested.

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Boxelder (Acer negundo)

Boxelder Leaves Boxelder Twigs Boxelder Fruit
Boxelder is a relatively common tree along streams and other bottomland habitats but may also be found on drier sites. At the Arboretum it can be seen in several places such as along Old Kerr Hollow Road and near the lower end of Cemetery Ridge Trail. Its range includes much of North America and extends south to the mountains of Mexico and Guatemala. The pinnately compound leaves of Boxelder, typically with 5 to 7 toothed leaflets, distinguish it from other maples. Young trees often have only 3 leaflets and can be confused with poison ivy - however, Boxelder can be distinguished by its opposite leaves, green twigs with reddish brown upper surfaces, and lack of vine-like growth. This small to medium-sized tree (50-75 ft tall) is short-lived with an average age of 60 years. It is dioecious (the male and female flowers are borne on separate trees) and produces abundant fruits in drooping clusters that remain on the trees into the winter months. The winged seeds (samaras) provide food for birds and other wildlife. The brittle wood has limited value - it has been used for making boxes and low quality furniture. Its low heating value makes it a poor source for firewood. Boxelder is tolerant of drought and cold and, in the West, has been used as a street tree and for shelterbelts. Boxelder Bug, an insect associated primarily with female Boxelder trees, does relatively little damage to the trees, but as temperatures become colder in the fall, it may invade houses in large numbers and become an annoying pest.

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Boxwoods (Buxus spp.)

Boxwoods Bed Although Boxwoods are native to parts of Europe, northern Africa, the Mediterranean region, and Asia, they have been used in North America for landscaping since colonial times. There are an estimated 70 to 80 species of boxwood, two of which - Buxus sempervirens (Common Boxwood) and B. microphylla (Littleleaf Boxwood) - have been used extensively to develop many hybrids and cultivars. Boxwoods are evergreen shrubs with opposite leaves that produce small yellow-green male and female flowers in the late spring or early summer. Although the flowers are not conspicuous, they are quite fragrant and attractive to bees. Because Boxwoods respond well to pruning, they are used for hedges, foundation plantings, topiary gardens, bonsai, and many other landscaping purposes. Most boxwood plants used for landscaping are small to large shrubs, but species such as Common Boxwood can grow to heights of 20 ft or more if not subjected to pruning. The wood from such plants is very hard and heavy and has historically been used for cabinet making (hence the name boxwood), engraving blocks for printing, handles for tools and daggers, and parts of musical instruments. A planting of 20 different boxwood hybrids and cultivars adjacent to the Arboretum's Program Shelter is being evaluated by UT researchers.

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Broad Beech Fern (Phegopteris hexagonoptera)

Broad Beech Fern A number of ferns at the Arboretum are not commonly seen along the trails, but may occur in areas not open to the public. One of these, the Broad Beech Fern, is sometimes seen along the South Forest Loop Road and probably occurs at a variety of other sites off the trails. Some of its distinguishing characteristics are: (1) a triangular leaf shape - the leaves are typically as wide at the bases as they are long; (2) the rachis of the leaf (the central stalk) is winged; (3) the compound leaves are bipinnatified (i.e., the primary divisions of the leaf (the pinna) are themselves subdivided into secondary divisions); (4) the lowermost pinna tend to point downward; and (5) the spore-bearing structures (sori), borne on the underside of the leaf, are arranged in two rows near the center of the primary pinna and have no indusia (membranous cover). Broad Beech Fern is found throughout Tennessee, and its range extends throughout the eastern half of the US and north into most of the eastern Canadian Provinces.

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Yellow Buckeye (Aesculus octandra)

Yellow Buckeye Yellow Buckeye produces conspicuous inflorescences of yellow flowers in May. Several large trees can be seen near the Marsh Area of the Arboretum. You will also see many young buckeyes with palmate compound leaves of 5 leaflets along the Tulip Poplar Trail, the Old Kerr Hollow Road, and the Cemetery Ridge Trail.

The common name Buckeye is based on the large brown seed with a large pale scar that looks like the eye of a deer. The Buckeye seeds are poisonous. Other species of the genus Aesculus you may see in the area include Horse Chestnut frequently planted in urban areas, Red Buckeye a small tree or shrub with red flowers, and Ohio Buckeye distinguished by the rank odor of crushed leaves or stems.

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Buttonbush (Cephalanthus occidentalis)

Buttonbush Bush Buttonbush Button Buttonbush Button

In early July, a Buttonbush located along Scarborough Creek near the entrance to the Arboretum displays the impressive white spheres of tightly compressed flowers that give rise to its common name. This shrub, a member of the Madder Family (Rubiaceae), may grow to a height of 20 ft. Its leaves are mainly opposite, but whorls of three leaves may occur just below the inflorescence.

It occurs along the edges of wetland habitats such as stream banks and marshes from Southern Canada south to Florida and west to the Great Plains. It can also be found in New Mexico, Arizona, California and northern Mexico.

Although the leaves are poisonous to cattle, waterfowl and song birds eat the small nutlets, and the shrub provides excellent cover for a variety of birds and wildlife. Buttonbush has been used for medicinal purposes by Native Americans. The bark contains an alkaloid, cephaeline, which is used in medications to induce vomiting, but it also contains cephalanthin, a poison that dissolves blood corpuscles.

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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