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Native Deciduous Magnolias
(Magnolia acuminata, M. fraseri, M. macrophylla, M. tripetala)

Four species of native deciduous magnolias found in East Tennessee bloom in late April and May. Specimens of all four can be seen at the Arboretum.

Cucumber Tree Cucumber Tree (M. acuimata) is widespread in eastern North America and is one of the more common magnolias found in the Oak Ridge area. It produces greenish-yellow flowers in late April and has leaves 4 to 12 in. long with pointed (acuminate) tips. The fruit is green when young, resembling a cucumber, and turns pink to red in the fall as it matures. The bitter fruits purportedly were used in the past to flavor whiskey. The wood has been used for furniture pallets, crates, and plywood.

Fraser Magnolia Fraser Magnolia (M. fraseri) is found in the Southern Appalachians. Its large leaves (usually 10-15 inches in length, but up to 20 in. long, and 6 in. or more wide) have ear-shaped lobes at their base and are broadest above the middle. Its flowers have creamy white petals and are up to 10 in. across. The trees are often branched at the base.

Big Leaf Magnolia In our area of E. Tennessee, Bigleaf Magnolia (M. macrophylla) Is found most commonly in the Smoky Mountains and on the Cumberland Plateau. It has very large leaves (12-36 in. long, 7-12 in. wide) that are bright green above and fuzzy, silver/gray beneath. The leaves are lobed at the base and widest near the tip. The large ivory colored flowers are 10-20 inches in diameter and appear in late spring/early summer.

Umbrella Magnolia Umbrella Magnolia (M. tripetala) is found throughout E. Tennessee. Its leaves are 10-24 in. long, tapered at the base, and usually widest near the tips. The leaves occur as whorled clusters at the tips of the stem, resembling an umbrella. The creamy white flowers are 6-8 inches in diameter.

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Southern Magnolia (Magnolia grandiflora)

Southern Magnolia By mid-June, Southern Magnolia is in full bloom, although flowers may be seen as early as late April or early May. Some flowers continue to appear throughout the summer. This evergreen tree, native to the southeastern Atlantic coastal plain from southern North Carolina to central Florida and west along the Gulf Coast to Texas, has been planted extensively throughout the Southeast and has escaped into surrounding urban woodlands. Its large (5-8 in. long), elliptic leaves are shiny dark green above, with a velvet rusty surface underneath. When shed in the spring and early summer, the dry, leathery leaves decay very slowly and have been found to be alleopathic (releasing chemicals that inhibit the growth of other plants).

The large, fragrant, creamy white flowers (up to 12 in. diameter), borne at the tips of branches, have many pistils and stamens in a central column, surrounded by undifferentiated sepals and petals (tepals). The flowers are pollinated by beetles. In late summer the erect pinkish fruits mature and, over the winter and the following spring, shed their scarlet seeds. Southern Magnolia typically grows to heights of 50-80 ft with a columnar to rounded shape. The tallest trees reported are over 100 ft high. Several cultivars of Southern Magnolia can be seen near the Visitors Center.

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Umbrella Magnolia (Magnolia tripetala)

Umbrella Magnolia Plant Umbrella Magnolia Bud Umbrella Magnolia Blossom
Umbrella Magnolia is one of several native deciduous magnolias found in our area. A fairly large tree is found next to Scarborough Creek just to the northwest of the Arboretum entrance. Other examples can be seen along Old Kerr Hollow Road and the Tulip Poplar Trail. The large leaves (up to 24 in. long) are widest near the tips, narrowing to the base - two similar species in our region, Fraser Magnolia (M. fraseri) and Big Leaf Magnolia (M. macrophylla), differ in having earlike lobed leaf bases. The common name reflects the arrangement of its leaves clustered at the tips of the branches, resembling an umbrella. The large flowers, pale yellow to creamy white, are pollinated by beetles. Umbrella Magnolia is found throughout the Appalachians and Blue Ridge Mountains from Pennsylvania south to Georgia and Alabama, and west to Arkansas and Mississippi. It frequently occurs in mesic habitats such as along streams and creeks.

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Bigleaf Maple (Acer macrophyllum)

Bigleaf Maple Leaf Bigleaf Maple Branches

The Arboretum's Shade Tree Collection has a variety of interesting maples from around the US and other countries. A specimen of Bigleaf Maple from the Pacific Northwest was planted here in 1965. This species ranges along coastal regions from Vancouver Island and coastal British Columbia south to California. As the name implies, Bigleaf Maple is characterized by large (5-12 in. wide), deeply divided leaves that exude a sticky, milky juice when broken. The bark is grayish-brown becoming shallowly grooved with age. In its native habitat, this tree grows to heights of 100 ft and often supports a thick mat of epiphytic mosses, lichens, and ferns. The wood is used for making furniture, musical instruments, plywood, veneer, pallets, and firewood. The sweet sap can be used to make maple syrup.

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Paperbark Maple (Acer griseum)

Paperbark Maple Leaves Paperbark Maple Bark A recent addition to the Arboretum's tree collection is a young Paperbark Maple planted behind the Visitors Center. It was donated by Ann and Lou Arnold in memory of Dr. Ted Rogers, a long-term supporter of the Arboretum and past President of the UT Arboretum Society. The most striking feature of this species is its exfoliating, papery bark that is brown to reddish brown, peeling away to a cinnamon to orange-brown color. Its opposite, compound, trifoliate leaves are dark green turning to an orange-red color in the fall.

Paperbark Maple Paperbark Maple is a slow growing tree and is used primarily as an ornamental specimen for a variety of landscape settings as well as for Bonsai. Paperbark Maple is a native of central China and grows 20-35 ft in height. It was introduced into the U.S. by E. H. Wilson in 1907 through the Arnold Arboretum.

In the 1990's, the North America-China Plant Exploration Consortium (NACPEC) undertook efforts to collect additional specimens from China to enhance the genetic diversity of the U.S-propagated Paperbark Maples, all of which were apparently derived from the first introduction.

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Purpleblow Maple (Acer truncatum)

Purpleblow Maple Tree A variety of ornamental maples are planted in the Arboretum's Shade Tree Collection. One of these, the Purpleblow Maple (also called Shantung Maple), produces a conspicuous display of greenish-yellow flowers in late March and early April. This tree, native to China, Manchuria, and Korea, grows to heights of 20 to 25 ft., with a broad, rounded crown. Its distinctive green leaves have three prominent sharp lobes with two smaller lobes along the flattened (or truncated) base. The samaras (two-winged, two-seeded fruits) are 1 to 1.5 in. long. The bark of young trees is smooth and often has a purplish hue, but it becomes ridged as the tree matures. In the fall, the leaves turn yellow to orange with prominent dark red leaf veins.

Purpleblow Maple Spring Purpleblow Maple Flower Purpleblow Maple Fall

Several cultivars have been developed with distinctive yellow to red foliage. This tree has a variety of uses. The sweet sap can be collected in the spring - it is less concentrated than the sap of sugar maples, and is used primarily as a drink. The leaves have been used as packing material for apples and root crops, and leaf extracts exhibit antibacterial activity. The dense wood has been used as a fuel.

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Red Maple (Acer rubrum)

Red Maple Red Maple Leaves
Red Maple is found on a wide variety of sites throughout the Arboretum's forests. Its fall foliage presents a brilliant display of color from bright yellow and orange to red. The opposite, palmate leaves are mostly 3-lobed but sometimes have 5 lobes. In the summer, the leaf petioles (leaf stalks) are often red and the undersides of the leaves are pale green to silver. In spring, red maple is one of the earliest trees to bloom (as early as February or March). Its small red flowers produce abundant seeds that are eaten by squirrels, birds, and other wildlife.

Red maple is found throughout the Eastern U.S. and Midwest - from the Maritimes in Canada and New England, to Florida, and west to Texas and Minnesota and states in-between. A number of excellent cultivars are available that are among the most popular landscaping tree species available.

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Red Mulberry (Morus rubra)

Red Mulberry Red Mulberry is a relatively small tree (30-80 ft tall) that can be found along several Arboretum trails — Old Kerr Hollow Road, the Cemetery Ridge Trail, and the Backwoods Trail. A large Red Mulberry tree is present just below the Superintendent’s House along the Valley Road. Red Mulberry is found throughout the Eastern U.S., but it is disappearing in parts of New England and Michigan, possibly due to bacterial disease. It typically occurs as scattered individuals in a variety of moist forest habitats and along fence rows and roads.

The alternate, serrate leaves are ovate to orbicular in shape and vary from being highly dissected and lobed to non-lobed — our trees tend to have few if any lobes. Red Mulberry is commonly dioecious (i.e., with separate male and female trees), but can be monecious with both male and female flowers on the same tree (see photo below).

Red Mulberry Flowers Red Mulberry Fruit In late May and June you can find Red Mulberry fruits ripening. When mature, the black fruits, resembling elongated blackberries, are favorite foods for many birds and small mammals such as squirrels, opossums, and raccoons. The juicy aggregate fruits have been used for jams, pies, and wines. The decay-resistant wood is used for fence posts, furniture, caskets, and farm implements. Native Americans used the bark to make fibrous cloth. They also used the plant to treat dysentery and as a laxative or purgative. Unripe fruits and the milky sap are poisonous. Pollen from Red Mulberry is a severe allergen.

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Mayapple (Podophyllum peltatum)

Mayapple Mayapple is found throughout the Arboretum in small to large patches. It is especially conspicuous along the Oak-Hickory Trail, parts of the Cemetery Ridge Trail, and the Backwoods Trail in the early spring. Flowers will begin opening in mid-April.

Look for plants with two palmate leaves - the white flowers are found at the base of the petioles (stalks) of the two leaves. The pulpy fruit (the "apple") develops as the spring progresses and is the basis for the common name Mayapple. Although the leaves and roots are poisonous, extracts from the roots have been used for a variety of medicinal purposes such as treating jaundice, constipation, and hepatitis. A derivative from this plant has been approved for treatment of some cancers.

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Common Milkweed (Asclepias syriaca)

Milkweed Leaves Fritillary on Milkweed In 2014, the University of Tennesse Arboretum Society established a Monarch Waystation in the Visitors Center Wildflower Garden to help conserve and protect habitat for declining populations of Monarch Butterflies. Common Milkweed is an important element of this habitat, providing food and shelter for Monarch Butterfly caterillars and adults. Common Milkweed is found in fields, along roadsides, and other open, disturbed habitats throughout the eastern U.S. It may grow to heights of 6 feet and has broad green leaves up to 6 inches in length. The pinkish flowers appear in early summer and attract a variety of butterflies, bees and other insects. The greenish fruits turn brown in late summer and release large numbers of fluffy seeds that are dispersed by the wind.

Milkweed Bugs Milkweed Tussock Moth Caterpillars The milky sap contains cardiac glycosides that are poisonous to some insects and birds. Monarch Butterfly caterpillars, however, can feed on Milkweed without ill effect. The glycosides that are incorporated into their bodies discourage predators from feeding on them. In late summer orange and black Milkweed Bugs and Milkweed Tussock Moth Caterpillars are often conspicuous feeding on Milkweed pods and leaves.

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Silk Tree or Mimosa (Albizia julibissin)

Mimosa Mimosa Leaves Mimosa Flower
Silk Tree (commonly known as Mimosa) is found along highway and powerline rights-of-way, forest edges, and other disturbed areas. A native of Asia, it was introduced into North America as an ornamental during the 18th Century and is now considered an invasive plant - it is listed in the category "Severe Threat" by the Tennessee Exotic Pest Plant Council. A few trees occur at the Arboretum, but they have been managed as invasives and do not pose a significant problem. Silk Tree is a member of the bean family (Fabaceae) and has large twice-compound (bipinnate) leaves (up to 20 in. long); light to dark pink, thread-like flowers; and flat bean-like seed pods (5-7 in. long). The flowers attract hummingbirds, bees, and other insects. It is used as an ornamental throughout its range and has soil building properties related to nitrogen-fixing bacteria in its root nodules. Landscape ornamentals are susceptible to Mimosa Wilt which causes leaf yellowing and wilting in early and midsummer and results in death of the plants. Silk Tree produces abundant long-lived seeds, and it sprouts vigorously when cut back - features that promote its invasive character.

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Mistletoe (Phoradendron leucarpum)

Mistletoe Black & White Clumps of Mistletoe resembling large green squirrel nests become conspicuous in the upper branches of deciduous trees after the leaves have fallen. Sprigs of its green leathery leaves and stems and its white berries are a familiar component of the Christmas time tradition of kissing under the Mistletoe. In ancient times it was used by Druid and pre-Christian traditions to decorate houses at the mid-winter and mid-summer solstices. In our area, Mistletoe is found on such trees as oaks, hickories, red maples, and sweetgums.

Mistletoe Mistletoe Although not commonly found at the Arboretum, Mistletoe is frequently seen in Oak Ridge, Clinton, and along the Pellissippi Parkway. It is considered to be semi-parasitic because its modified roots penetrate the bark and vascular tissues of the host tree and access water and minerals for the developing plant, but it does not appear to harm the host. In the winter, Mistletoe clumps consist of a heavily branched system of greenish stems bearing opposite, leathery, leaves containing chlorophyll. While these clumps are heavily shaded by the host tree's canopy during the summer, they are well adapted to photosynthesize after leaf fall - it has even been suggested that they may contribute food to the host tree during the winter months.

Mistletoe bears inconspicuous yellow flowers and white, translucent berries. Birds disperse the seeds in their droppings and by wiping sticky residues of the fruits adhering to their beaks onto other trees. Phoradendron leucarpum occurs throughout much of the eastern US from New Jersey to Florida and as far west as Texas and Illinois. Species of Mistletoe in the western US are parasitic on conifers and can be a significant problem.

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Mountain Laurel (Kalmia latifolia)

Mountain Laurel Mountain Laurel is an evergreen shrub that may attain the size of a small tree. The showy clusters of flowers are normally pink, but fade to white. In May, a beautiful example of Mountain Laurel can be seen in bloom near the Arboretum entrance just below Old Kerr Hollow Road.

Mountain Laurel is found in a variety of habitats in the Eastern U.S., ranging from high-altitude heath balds to dry and rocky forests to floodplains. Other common names for Mountain Laurel include "Sheepsbane" and "Poison Laurel", reflecting the highly poisonous nature of all parts of the plant. It has also been called "Spoonwood" because Native Americans used the roots to make spoons and other small eating utensils. Numerous cultivars have been developed for horticultural uses.

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Multiflora Rose (Rosa multiflora)

Multiflora Rose

From late April through the month of May and often well into June, Multiflora Rose is found flowering in a variety of habitats at the Arboretum. This invasive species has abundant, fragrant white flowers. The shrub is perhaps most conspicuous along the edges of forests, streams, and open areas. Its arching stems can develop into dense thickets, growing over native vegetation and becoming impenetrable due to the stout, recurved thorns along the branches.

Multiflora Rose Flowers The alternate, compound leaves have 5-11 leaflets with characteristic feathery stipules at their bases. The fruits (rose hips) develop in mid-summer and are eaten by a variety of birds and other wildlife, facilitating their dissemination. The UT Forest Resources Center, in cooperation with UT faculty, is presently engaged in the testing of new herbicides to help eradicate this shrub and other invasive, non-native plants.

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Muscadine Grape (Vitis rotundifolia)

Muscadine Vine Muscadine is one of at least three conspicuous grape species found at the Arboretum. The large twisted vines and distinctive leaves of the Muscadine grape are commonly seen along many of the Arboretum's trails. Muscadine grapes flower in June and produce their tasty fruits in September and October (below left photo.) At this time of year, one can see the ripening deep purple to bronze fruit on vines which have climbed small trees or shrubs. The larger vines produce their fruit in the upper forest canopy making them more difficult to see. The fruity odor of the grapes often provides a clue to their presence in the canopy. Plants with a bronze or golden green fruit are commonly called scuppernongs. Muscadine is used in home-made wines and jellies and is an important wildlife food.

Muscadine Grape Fruit Fox Grape Summer Grape

Both Fox grapes and summer grapes are also found along our trails. Fox grapes (above center photo) produce many smaller grapes in elongate bunches. This species has been hybridized with European grapes to provide resistance to a disease introduced from North America that devastated Europe's vineyards in the 1860's. Summer grapes (above right photo) have distinctive lobed leaves. These and the other grape species are a food source for birds and other wildlife.

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