Two large, impressive trees in the Arboretum’s Conifer Collection are the Japanese Cedars on the hill above the Program Shelter and the Oak Collection. These are not true cedars, but belong to the Cupressaceae family, which also includes junipers, bald cypress, arborvitae, and redwoods. A dwarf form of this tree can be found in the Dwarf and Unusual Conifer Collection. This ancient tree is the National tree of Japan and is also called “Temple Tree” for its use in building the centuries-old Shinto temples. It has a pyramidal, conical shape with somewhat pendulous branches. It is evergreen and grows 50-60 ft high — though old trees as high as 230 ft have been reported.
Japanese Cedar has blue-green, needle-like leaves and a red-brown bark that peels off in vertical strips. The seed cones are globular. It is a forest tree native to Japan (16% of Japanese managed forests are of Japanese Cedar). It has a wide variety of uses in construction and the manufacture of furniture, utensils, and paper. Japanese Cedar is cultivated as an ornamental, landscape tree, and is frequently used for Bonsai.
Eastern Red Cedar/Old Field Juniper
Eastern Red Cedar (also known as Old Field Juniper) is a small to medium sized coniferous tree with scale-like or awl-like leaves and bluish, berry-like fruits. It is widespread throughout the eastern U.S. and adjacent Canada. It invades open areas that have been disturbed by fire or cleared for agriculture. Individual trees may persist in older forests for many years. As you walk the trails at the Arboretum, you may see older Eastern Red Cedar trees that indicate clearing for past land use or smaller trees that have developed in forest openings.
Several different cultivars of Juniperus virginiana can be found in the Juniper Collection near the Program Shelter. The “Cedar barrens” behind Jefferson Middle School in Oak Ridge is an example of an area currently dominated by Eastern Red Cedar.
In late winter, Eastern Red Cedar produces a copious amount of pollen that is a potent allergen. The female cones develop into bluish “berries” with a waxy coating. The fruits provide an important winter food source for birds which disperse the seeds widely. The aromatic wood repels insects and is used for lining cedar chests and as fence posts. The tree also is planted for windbreaks and is used for making pencils and for Christmas Trees in the South. The Forest Resources Center crews utilize these trees for fence posts, bird houses, and kindling in the operations of the Center. Eastern Red Cedar is an alternate host for cedar-apple rust and should not be planted near fruit trees. Berries from a related species, Juniperus communis (Common Juniper), are used to flavor gin.
Hollies (Ilex species)
Hollies are found throughout the world occupying a wide range of habitats. More than 780 native evergreen hollies and 30 native deciduous hollies have been recognized. Although North America is not considered a major center of holly diversity, it does have 23 native hollies, with 7 occurring in Tennessee. Many holly cultivars have been developed and are used extensively in landscaping. Hollies have a rich history of medicinal uses and have been regarded as religious symbols. They are also used widely for wreaths and other holiday decorations.
The Harold L. Elmore Holly Collection at the UT Arboretum is a research and display garden containing over 200 evergreen and deciduous Holly cultivars. Named in honor of the late Harold Elmore, a past president of the University of Tennessee Arboretum Society as well as the Holly Society of America, it is recognized by the Holly Society of America as an official collection of Hollies. As part of this collection, a variety of deciduous hollies have been planted in the Arboretum’s Marsh Area. Other Holly plantings are found along Valley Drive and Shade Tree Lane.
American Holly is found as an understory tree in a variety of habitats throughout the Arboretum. Although it can grow to heights of 50 to 60 feet, most of the trees along the trails are much smaller, reflecting their slow growth rate and the relatively recent disturbance history of our forests. After the leaves have fallen, these trees become more readily visible with their spiny, evergreen leaves. The fruits (4-seeded drupes) are collected along with the leaves for Christmas wreaths and other holiday decorations. The fruits are eaten by birds and small mammals, but can be toxic to humans and pets. The wood is suitable for inlays in cabinet work, handles, carvings, rulers, and scientific instruments. When dyed black to resemble ebony, the wood is used for violin pegs, piano keys, and fingerboards.
Ginkgo (Ginkgo biloba)
Ginkgo (or Maidenhair Tree) puts on its spectacular fall display toward the end of October or early November. For a short period its leaves turn bright yellow, and then almost overnight, they fall to the ground creating a conspicuous leaf shadow under the tree’s spreading branches. Two beautiful Ginkgo trees can be seen across the Arboretum entrance road from the Visitors’ Center, and another is located near the end of Marsh Road as it turns up to the Forest Loop Roads.
Ginkgo is a Gymnosperm (naked seed) — its developing ovules and seeds are not enclosed in an ovary. Its fan-shaped leaves resemble those of Maidenhair Fern (hence its common name) and have dichotomous (forked) venation. Ginkgo is well-represented in the fossil record. For thousands of years it only survived in temple gardens in China, and no wild populations are known to exist. The tree is often referred to as a living fossil.
Ginkgo is dioecious (i.e., meaning two houses) with separate male and female trees. The male trees are most commonly planted because the female trees produce fruits with a strong, unpleasant odor. Ginkgos are hardy trees that are planted in many parts of the U.S. and elsewhere. Extracts from Ginkgo leaves have been used for medicinal purposes for many years.
Persimmon (Diospyros virginiana)
Persimmon is a moderately sized tree growing to 60 feet in height and 2 feet in diameter. It is the most northern member of the Ebony plant family — other members of the family are tropical or subtropical. A number of Persimmon trees are found along Arboretum Drive and on the edge of the Shade Tree Collection. In September/October, these trees may be loaded with orange fruits that become deep purple as they age.
Persimmons are dioecious — meaning that male and female flowers are found on separate trees. The leaves and fruits of the tree are astringent, and have been described as puckery. However, when mature, the fruits lose their astringent tannins and become sweet and delicious. The genus name Diospyros can be translated from the Greek as "food for the gods."
Persimmon is native to the Eastern U.S. — New England to Florida, west to Texas, Iowa, and Kansas. The bark is dark brown to black and is deeply divided into small blocks. The dense wood has been used for such purposes as golf club heads and billiard cues.
Fall Wildflowers 2014
Pignut Hickory (Carya glabra)
Pignut Hickory (Carya glabra) is one of several hickory species found in our Arboretum forests. It is found throughout the Eastern U.S. and north into southern Ontario. It is one of the most common hickories in the Appalachians. The common name was given by early settlers because the abundant nuts provided food for free-ranging hogs. It’s alternate, compound leaves typically have 5 (occasionally 7) glabrous leaflets (i.e., without hairs) that are finely toothed. The pear-shaped to ovoid fruits are about 1" in diameter, with thin husks and nuts that are not ribbed. A distinctive feature of the fruit is that when mature, the husk only splits about half-way along the fruit axis. The bark is relatively tight, has vertically oriented ridges that are rounded, and may be flaky. The nuts, which are high in crude fat and have moderate content of proteins, calcium and phosphorus, are an important food for a variety of mammals, such as squirrels, chipmunks, and black bear, as well as some birds such as turkeys, woodpeckers, pheasants and several songbirds. The strong, hard, tough wood is used for making tool handles, fence posts, sporting goods, agricultural implements, and as fuel wood. Early settlers used thin splits of the wood to make brooms.
Sourwood (Oxydendrum arboreum)
Sourwood is a small to medium-sized tree found along many Arboretum trails. It ranges from Pennsylvania, Ohio, and Indiana, south to northwest Florida, Alabama, Mississippi, and Louisiana. As a member of the Heath Family (Ericaceae), it is related to such plants as blueberries, rhododendrons, and azaleas. The white, bell-shaped flowers are borne in terminal one-sided clusters and appear in late June and July. The fruits mature in late summer and persist on the flower stalks, often into fall and winter. Because the flowers are often near the top of the trees, they may be difficult to see under a forest canopy. The finely toothed leaves, 5-8 in. long, turn a yellow to crimson red in the fall. A good place to observe these trees in bloom is a Sourwood study plot just below the Arboretum’s Elmore Holly Collection.
The ridged and often deeply furrowed bark of Sourwood is readily identified especially in older trees where it becomes distinctly blocky. Trees may grow 50-60 ft high, with trunks that are often bent or leaning. The common name comes from the sour taste of the leaves and twigs. Leaves and bark of Sourwood were used by Native Americans and early settlers to treat a variety of ailments such as mouth ulcers, asthma, indigestion, and kidney and bladder ailments. Sourwood has little timber value, but the heavy wood has been used for handles, fuel wood, and specialty items. Sourwood honey is a favorite of many.
Dawn Redwood (Metasequoia glyptostroboides)
Dawn Redwood is a deciduous conifer with flat, needle-like leaves that turn a copper-colored brown in November. A specimen of this tree, planted in 1965, can be seen in the Arboretum’s Central China Collection near the end of Marsh Road. Dawn Redwood is related to Bald Cypress (Taxodium distichum) of the southeastern U.S. and to California’s Redwood (Sequoia sempervirens) and Giant Sequoia (Sequoiadendron giganteum).
In the early 1940s, a Chinese paleobotantist recognized that fossils initially thought to belong to the genus Sequoia, should be reassigned to a new genus, Metasequoia. In 1945, living individuals of Metasequoia glyptostroboides were found in the Sichuan Province of China. Extensive field surveys in the late 1940s found this “living fossil” present in limited populations in both Sichuan Province and neighboring Hubei Province. Propagation of seeds and cuttings at arboreta in the U.S. and elsewhere resulted in Dawn Redwood becoming available for planting. Although Dawn Redwood does not have wide-spread commercial value, its lumber is similar to that of Coastal Redwood and has been used to make furniture as well as pulp for making plyboard and composite materials.
Metasequoia is a fast growing tree — some of the oldest U.S. trees (planted in 1948) have attained diameters of over 1 meter. Dawn Redwood can be distinguished from Bald Cypress by several characteristics — the buds develop on the underside of the branches not along the tops; the leaves are opposite, not alternate; the base of the trunk is fluted and buttressed; and the branches have rounded depressions below their junction with the trunk. The light brown pollen cones are borne on long stalks appearing in early spring; the inconspicuous female cones are borne singly.
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.
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.