The University of Tennessee - Forest Resources Research and Education Center

As one walks the Arboretum trails at this time of year, the fruits of a variety of woody plants and vines can be seen. Our native Dogwood, American Holly and Greenbriar are found along with several non-native, invasive plants, such as Oriental Bittersweet, Chinese privet, and Amur Honeysuckle. Some of these fruits, such as those of the Dogwood provide food for a variety of birds (e.g., robins, cedar waxwings) and small mammals. Six of the more common winter fruits found at the Arboretum are described below.

Left: Flowering Dogwood (Cornus florida)
Right: Oriental Bittersweet (Celastrus orbiculatus)
American Holly Fruit

Left: American Holly (Ilex opaca)
Right: Chinese Privet (Ligustrum sinense)
Amur Honeysuckle Fruit

Left: Amur Honeysuckle (Lonicera maackii)
Right: Greenbriar species (Smilax sp.)

Japanese Nutmeg (Torreya nucifera)

Early to Mid January

A native of Japan, this small evergreen tree belongs to the yew family (Taxaceae). It is one of five species of the genus Torreya, two of which are native to the U.S. (T. californica and T. taxifolia). A good example of Japanese Nutmeg can be seen at the upper end of the Arboretum’s Dwarf Conifer Collection next to the Valley Road. The leaves are two-ranked, and when crushed, they are have a pungent odor.

At this time of year, double rows of the male strobili (pollen cones) are conspicuous along the underside of some of the branches. The male and female cones are often found on separate branches of the same tree. The fruit is a single seed surrounded by a fleshy structure similar to the aril of yews. The nut-like seeds are edible and are pressed for a type of cooking oil.

In Japan this species may reach a height of 75 ft. The wood is highly valued for construction of boards used for the ancient game of Go. The species has been over-harvested in Japan and has become rare.

Seaside Alder (Alnus maritima)

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.

Hinoki Cypress (Chamaecyparis obtusa)

A variety of trees belonging to the plant family Cupressaceae are commonly called "Cypress." At the Arboretum, several plantings in the Conifer Collection and the Dwarf and Unusual Conifer Collection belong to the genus Chamaecyparis and are known as Cypress or False Cypress. The Hinoki Cypress is a native of Japan and Taiwan. It has scale-like leaves borne on spreading branches that are in flattened planes. Dwarf cultivars of this species are commonly used in landscaping. An example of one of these dwarf cultivars is Chamaecyparis obtusa 'Filicoides', which can be seen in the Dwarf and Unusual Conifer Collection.

Sawara Cypress (Chamaecyparis pisifera)

Sawara Cypress, considered a sacred tree in Japan, is a valuable timber species in that country. Although the original species may grow as high as 60 ft, many of the cultivars have been selected to produce dwarf plants that are used extensively in landscaping. A good example present in the Conifer Collection is Golden Threadleaf Sawara Cypress (Chamaecyparis pisifera 'Filifera Aurea Nana'). It has drooping yellow, threadlike foliage and reddish-brown bark that peels on older trees. This cultivar is generally described as a dwarf form, but our specimen is much taller. The Cupressaceae is a large family that includes 18 genera and many familiar plants at the Arboretum such as Junipers, Cedars, and Bald Cypress.

Vernal Witch Hazel (Hamamelis vernalis)

It's always somewhat surprising to find plants in bloom in January, but despite the recent cold temperatures, a shrub next to Scarboro Creek just below the Arboretum Visitors Center blooms late in the month. Vernal Witch Hazel is a native of the Ozark and Ouitchita Mountains. Its very fragrant flowers vary in color from yellow to purplish-red and usually bloom in late January or early February. The common name Witch Hazel purportedly comes from the belief that witchcraft allowed the crooked stems of the shrub to be used for divining water. The flowers of our native American Witch Hazel (Hamamelis virginiana) have 4 yellow strap-shaped petals and are less showy than those of Vernal Witch Hazel. Witch Hazel belongs to the plant family Hamamelidaceae. The only other genus in this family native to the U.S. is Sweetgum (Liquidambar styraciflua).

American Witch Hazel (Hamamelis virginiana)

American Witch Hazel is in bloom next to Scarboro Creek below the Visitors Center. It is distinguished at this time of year by its four yellow, strapped-shaped, crumpled petals that first appear early in January. This tall shrub to small tree is found on a variety of habitats in many parts of middle and east Tennessee. It has forked branches, and its leaves resemble American Hazelnut (Corylus americana). The open, dried, capsule-like fruits can be seen on the flowering branches. Its fragrant foliage, twigs, and bark produce an extract that has been used as an astringent and toiletry. Its fruit is eaten by a variety of birds and other wildlife. Two individuals of a related species, Vernal Witch Hazel (Hamamelis vernalis), are also present next to the Creek. Their reddish to purplish flowers emerge toward the end of January.

Eastern White Pine (Pinus strobus)

Eastern White Pine, a common coniferous tree in our area, can reach heights well over 100 ft. It is easily distinguished from our other native pines by its light green needles borne in clusters (called fascicles) of 5. These flexible needles are 3 to 5 in. long. The resinous, cylindrical cones are 4 to 8 in. long and require 2 yrs to mature. The smooth gray bark of younger trees becomes furrowed with age. Eastern White Pine is widespread in Eastern Canada and the Northeast US, extending down the Appalachians as far as northern Georgia and South Carolina, and is found throughout the upper Midwest and adjacent Canada. In the 17th and 18th centuries, it was heavily logged by the British for ships’ masts. The White Pine Trail above the Arboretum Visitors Center formerly ran through a stand of relatively large, mature examples of this species. Disease and wind damage, however, have eliminated many of these magnificent trees. Read more about the White Pine Trail >>

Norway Spruce (Picea abies)

Norway Spruce, a native tree of north, central, and eastern Europe, has been widely planted in eastern North America and in parts of the Pacific Northwest and Rocky Mountains. A number of examples are present at the Arboretum near the top of the Tulip Poplar Trail and along the upper edge of the sinkhole area near the Program Shelter. This tree may grow to heights of 100 to 200 ft. It has characteristic pendulous branches with orange-brown twigs bearing short (1 to 2.5 cm) blunt-tipped needles. The tan-brown cones, 4 to 7 in. long, are found on branch tips in the upper third of the tree’s canopy. The bark becomes gray scaly as the tree matures. Norway spruce is used for lumber, pulp, musical instruments, Christmas trees, and as an ornamental. Several Norway Spruce research projects have been carried out on the UT Forest Resources Center, including growth and adaptation studies associated with genetic sources and improvement of needle retention for use as cut Christmas trees.

Loblolly Pine (Pinus taeda)

Several large specimens of Loblolly Pine are found near the Arboretum’s Program Shelter, and research plantings that were established in 2003 can be seen along Arboretum Drive. The needles of Loblolly Pine are typically borne in fasicles (bundles) of 3 (sometimes 4) — the yellow-green needles are longer (6-9 in.) than those of Virginia Pine and Shortleaf Pine. The elongate, cylindrical seed cones (6-9 in. long) mature in 2 years and do not persist on the trees as do those of Virginia Pine. Pollen cones appear in April and produce large amounts of pollen. The bark on older trees is dark gray-brown and deeply furrowed.

The native range of Loblolly Pine extends from southern New Jersey, south along the Coastal Plain and Piedmont regions to Florida, and west to eastern Texas. In Tennessee its native range extended only into the southern edge of the state, but it has been widely planted and is commonly seen along highways and in tree plantations in our region. It is an important pulpwood and timber tree throughout much of the Southeast.

Virginia Pine (Pinus virginiana)

Virginia Pine (also known as Scrub Pine) is one of the more common native pines found at the Arboretum. Its twisted, yellowish-green needles are borne in bundles of two, a characteristic that helps distinguish it from Shortleaf Pine which has straight needles in bundles of 2-3. Trunks of older Virginia Pine retain many dead limb stubs below the canopy. The flaky bark is light brownish orange to gray-brown. The seed cones, which require 2 years to mature, have scales with thickened ends bearing slender, stiff prickles. Pollen cones develop in the spring and produce copious amounts of pollen.

Virginia pine, which may grow up to 70 ft in height, is a pioneer species that becomes established in open areas created by fire or other disturbance. The presence of older Virginia Pines in the Arboretum’s deciduous forest reflects a history of forest development on abandoned farmlands. Research at UT on Virginia Pine has included studies of genetic and environmental variability that influence tree growth and productivity.

Deciduous Hollies

Late January to Early February

'Winterberry' (Ilex verticillata) is one of several deciduous hollies present in the Arboretum’s Marsh Area. These are part of the Elmore Holly Collection which is described in detail - including a full list of the collection and a site map.

Although one usually thinks of hollies as being evergreen, a variety of hollies lose their leaves each fall and provide a display of bright colored fruits at this time of year. 'Winterberry' is one of three native deciduous hollies found in East Tennessee - the others being Carolina Holly (Ilex ambigua v. amigua) and Mountain Holly (Ilex ambigua v. montana). Many culivars and hybrids using Winterberry have been developed including the four examples shown below that can be seen in the Marsh Area this winter.

Left: 'Winter Gold' (Ilex verticillata)
Right: 'Bonfire' (Ilex serrata x verticillata)
'Stop Light' Holly

Left: 'Stop Light' (Ilex verticillata)
Right: 'Earlibright' (Ilex verticillata)

Winter Fruits

Japanese Nutmeg (Torreya nucifera)

Seaside Alder (Alnus maritima)

Hinoki Cypress (Chamaecyparis obtusa)

Sawara Cypress (Chamaecyparis pisifera)

Vernal Witch Hazel (Hamamelis vernalis)

American Witch Hazel (Hamamelis virginiana)

Eastern White Pine (Pinus strobus)

Norway Spruce (Picea abies)

Loblolly Pine (Pinus taeda)

Virginia Pine (Pinus virginiana)

Deciduous Hollies