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Seaside Alder, a tall shrub found along Scarborough Creek below the Arboretum Visitors Center, is native to four counties on the Delmarva Peninsula of Maryland and Delaware, but is also found in south-central Oklahoma and northwestern Georgia. This unusual distribution is not well understood, but temperature and moisture regimes of the regions are somewhat similar. Recent studies suggest that these three distinct populations may be remnants of a former much larger distribution. Seaside Alder may reach heights of up to 20 meters. It has toothed elliptical to ovate leaves that are dark green above and pale green underneath. It is found on damp and wet soils in wetland habitats along streams, rivers and edges of ponds. This alder species has been used in the Philippines in efforts to reforest eroded lands. It has also been used for a variety of folk remedies and for dyes, insect repellants, insecticides, and possible emergency food.

Seaside Alder develops male catkins in the fall (male catkins have been observed in late August on our specimens). The small pistillate catkins develop near leaf bases. In their native habitat these flowers develop in the fall, while our plants develop the flowers in February and March. Seaside Alder has root nodules with symbiotic nitrogen-fixing bacteria, which convert inorganic nitrogen from the atmosphere to a form that can be used by plants.

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.

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.

Northern Red Oak, a fairly common tree in our deciduous forests, is found along many of the Arboretum trails. As the common name implies, it is most prevalent in northern hardwood forests, but is found throughout Tennessee. Its range extends from the Maritime Provinces and eastern Canada south to Alabama and Georgia, and west to Minnesota, Nebraska and Oklahoma. The lobes of the alternate, dark green leaves are bristle-tipped, a characteristic of other members of the red oak group, and turn brick red in the fall. In poor years, however, the leaves are likely to be red-brown to yellow. The acorns are up to 1 in. long and have a cap covering up to 1/4 of the nut. The bark is lightly to deeply furrowed, frequently with light-colored plates running up and down the trunks between the fissures. The acorns are prime food for squirrels, turkeys, deer, black bears, and other wildlife. Although Northern Red Oak frequently produces large crops of acorns, squirrels and other wildlife may consume 80 to 100% of the acorns in any given year. Northern Red Oak is an important lumber tree, with a wide variety of uses in construction and furniture making.

American Chestnut was a dominant tree in the eastern deciduous forest before the early 1920’s. Sources indicate that as many as one in four trees in our forests may have been American Chestnut. It provided durable lumber, tannins, and edible nuts. The arrival of the Chestnut Blight in the early 1900’s, however, resulted in the virtual elimination of this species by the 1940’s. As Richard Evans discusses in his Tree Facts article “The Lost Chestnuts”, old stumps and root sprouts of American Chestnut were present in Arboretum forests until recently and were the basis for developing and naming the Lost Chestnut trail. These remnants have now mostly disappeared, although root sprouts may still be present in the area.

In a talk at the UTAS annual meeting in November 2011, Bryan Burhans, President and CEO of the American Chestnut Foundation described the Foundation's efforts to develop blight resistant hybrid chestnuts from crosses between American Chestnut and Chinese Chestnut. A principal challenge is to develop hybrids that have the blight resistance of Chinese Chestnut but otherwise possess characteristics of the American Chestnut, including rapid growth, production of large numbers of chestnuts, and the ability to compete successfully in natural forest environments with other native species. Hybrids that are more than 90% American Chestnut are currently being tested at many different locations in the Eastern and Midwestern US, with the understanding that different hybrids that can adapt to different geographic regions and habitats will be needed.

UT researchers have been conducting studies to identify blight resistant strains of American Chestnut and to develop blight resistant hybrids. A number of studies have evaluated performance of American Chestnut planted on abandoned coal strip mines, both to evaluate the resistance of hybrids to Chestnut blight and to determine their potential use for reclamation. A related study at the UT Forest Resources Research and Education Center in Oak Ridge is evaluating the performance of native trees, including American Chestnut, on quarry spoils. The study is examining the effects of overburden preparation, response of trees to nitrogen fertilization and liming, and the success of pioneer vs later successional trees. Effects of the treatments on ecosystem processes such as changes in soil chemistry and photosynthetic rates are being documented.

One of the interesting trees in the Shade Tree Collection at the Arboretum is a Chinese Parasol Tree. In late October and early November, its large leaves (up to 12 in. wide) are bright yellow gradually turning to brown. This native of China, Japan, and southeast Asia, a member of the Cacao (cocoa) family (Sterculiaceae), is planted as an ornamental tree in the Southeastern US and has become naturalized in a few locations. The Chinese Parasol Tree grows rapidly to heights of 30 to 50 ft and develops vigorous sprouts around its base that need to be cut back periodically. This sprouting often results in multiple trunks. The wood has been used to make furniture and coffins. Medicinal uses have included salves and lotions to reduce swelling and treat such conditions as hemorrhoids, carbuncles, and sores.

In July, numerous branched inflorescences bear fragrant yellow/orange/green flowers that attract such pollinators as butterflies and bees.

The relatively smooth, light-colored bark has a greenish tint and has been used for fiber to make cordage and cloth. The female flowers develop into brown pods which split into four sections and are said to resemble parasols.

As you walk from the Program Shelter along the edge of the Arboretum’s Shade Tree Collection in early November, you may notice a tree bearing large globular fruits, many of which have fallen to the ground. As its name indicates, Chinese Quince is a native of Eastern China. Although related to other European and Asian Quinces, it has been placed in a separate genus. It may grow from 10 to more than 40 ft in height and develops a dense, twiggy crown. The alternate, simple, dark green leaves have serrated margins and turn yellow to red in the fall. The attractive fluted bark is flaky and is said to resemble the bark of Sycamore. Chinese Quince has been used to treat such illnesses as asthma, the common cold, and tuberculosis. The hard, dark red wood is used in making a variety of items such as knife handles, wooden bowls, musical instruments, and picture frames.

A member of the Rosaceae plant family, it produces fragrant, pink flowers in the spring — our specimen was in flower at the end of March in 2011. The large (as much as 7 in. long and 4 in. wide), astringent fruits become sweeter after frost and are used for making jams, syrups, and liqueurs.

Ginkgo (or Maidenhair Tree) puts on its spectacular fall display in 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. A beautiful Ginkgo 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 - 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, malodorous 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.

Chestnut Oak, a member of the White Oak group, is a major component of the forest along the Lost Chestnut and the Oak Hickory trails and is frequently found elsewhere at the Arboretum. Chestnut Oak is typically found on dry, rocky sites, often in hilly or mountainous terrain and is also known as Rock Oak or Rock Chestnut Oak. It is not shade tolerant and may form almost pure stands. Its range in the US extends from southern Maine to Georgia, Alabama, and Mississippi and west to southeastern Michigan, southern Indiana and Illinois. In the east, it is best developed in the Appalachians and is uncommon on the coastal plain. The heavy wood is strong and durable and used for lumber and fuel.

Its common name reflects the resemblance of its leaves to American Chestnut - however, Chestnut Oak has rounded teeth around the leaf margin, while the leaves of American Chestnut have sharp teeth. In the fall the dark green leaves turn yellow-brown.

The relatively large, brown acorns (1.5 in long) have a cup that covers less than half of the acorn. Along with other oaks, they contribute to mast production providing an important source of food for wildlife. The dark, deeply ridged bark has a high content of tannins and has been used extensively for the tanning of leather.

Post Oak, a small to medium sized tree, is mostly found along forest edges at the Arboretum. The heavy wood is resistant to decay and has a variety of uses such as railroad ties, mine timbers, and fence posts. Post Oak ranges from southern New England south to Florida and west to Kansas, Oklahoma, and Texas. It is tolerant of drought and is found on dry, sandy to rocky sites but also occurs on moister floodplains. In Texas and Oklahoma, Post Oak and Blackjack Oak are major components of the Cross Timbers - a dense forest of small trees forming the transition zone from forest to prairie grassland.

Its distinctive leathery leaves typically have five lobes, with the terminal three squarish lobes resembling a cross. The upper leaf surface is dark, shiny green in summer, while the lower surface is paler and covered with stellate (star-shaped) hairs. In the fall, leaves turn to a golden or bronze color.

The bark is similar to White Oak but not as flaky in older trees. The light to dark brown acorns are less than 1 in. length, with a cap covering about 1/3 of the nut.

Black Oak is a common and important tree in the deciduous forests of our area, as reflected in the name of the ridge on which the City of Oak Ridge is built. Its range extends throughout much of the Eastern and Midwestern US. Black Oak leaves are quite variable and often difficult to differentiate from other members of the red oak group, such as Northern Red Oak. The leaves are from 4-10 in. long with 7-9 bristle-tipped lobes. Their upper surface is shiny green, while the lower is a paler green. Shade leaves have relatively shallow lobes, while sun leaves are more deeply lobed. As fall progresses, the leaves turn yellow to bronze and then red. Seeds mature over a two-year period, germinating in the spring after they fall. Seeds are an important food for wildlife such as squirrels, deer, and turkey.

The smooth, gray bark of young trees becomes dark gray to black with deep furrows as it matures. The grayish pubescent terminal buds tend to be square in cross section. The inner bark is orange to yellow in color (“pumpkin” color), which is a diagnostic feature for identifying Black Oak. A scaly cap covers 1/3 to 1/2 of the brown acorn at maturity.

Although the seeds contain bitter tannins, these can be leached with water. The powdered acorns have been used as a thickening for stews and as a flour. Acorns have also been roasted as a substitute for coffee. The dense wood is used for furniture, flooring, railroad ties, rough lumber, and fuel.