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What's new in nature
BY CHARLES GARRATT • STAFF WRITER
 | | Nothing but a mass of berries and vines all the way up to the top of the tree, oriental bittersweet takes over and may eventually kill this tree along Route 39 near Warm Springs. The decorative red berries are easy to spot in winter and are often used in wreaths and other holiday decorations. The invasive oriental variety of bittersweet is displacing the native species and killing trees all over the Highlands. While the native bittersweet has berries only at the end of stems, the more prolific oriental variety has berries along the stems (inset). (Recorder photo by Charles Garratt) |
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WARM SPRINGS - Some plants are easier to find in the winter than during the growing season when they are hidden by or blend with the thick foliage of trees and shrubs. Bittersweet stands out particularly well in winter because of its decorative red and orange berries.
In the Highlands, there are two varieties of bittersweet. American bittersweet (Celastrus scandens) is indigenous to eastern North America and is rapidly disappearing from much of its native range. The vine climbing high into trees all over the highlands is the invasive oriental bittersweet (Celastrus orbiculatus), an alien introduced into this country in the 1800's.
It is the beautiful berries that make bittersweet stand out this time of the year and the berries are the reason the oriental variety of the plant arrived here 150 years ago. Oriental bittersweet is still planted by some people for use in wreaths and winter decorations even though it has become invasive in nearly two dozen states.
The oriental variety is favored for decorating because it has more berries than the native bittersweet. The prolific crop of berries and other traits are helping the oriental species to crowd out the native variety.
Unlike the native variety, oriental bittersweet is aggressive and fast growing and will take over trees, eventually killing them. State Forester John Wright points out the heavy load of bittersweet vine also makes trees more susceptible to damage from wind and ice.
Along Routes 39 and 220 near Warm Springs, large patches of oriental bittersweet are visible this time of the year in trees and along fences. This is a good time of the year for landowners to find the vines and mark them for eradication.
The Native American bittersweet should be preserved in the landscape if possible. Identifying a bittersweet as native or oriental can be difficult this time of the year. In general, according to author and nursery owner David Beaulieu, "It is oriental bittersweet vines that threaten to kill your trees; while American bittersweet plants are themselves threatened."
Wright and other forestry experts can help the landowner with positive identification of the bittersweet vines and suggest methods of control. Winter is a good time to locate the vines and mark them for identification and elimination come spring.
Oriental bittersweet kills trees by wrapping the trunk and branches so tightly the tree is effectively girdled according to Beaulieu on his website. If the vine doesn't kill the tree, the thick foliage and rapid growth shade the tree and starve it for sunlight. The heavy vines can also cause the tree to fall during high winds and ice storms.
The National Park Service alien plant program and the state of Virginia both list oriental bittersweet as highly invasive. A drive around the Highlands in the winter quickly shows just how dominate this plant loaded with pretty berries has become.
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