Rhizomes send up new shoots
Summer fruit, stem, and leaves
Infestation overwhelming spruce trees
Infestation smothering forest trees in Illinois. Photo: Chris Evans, River to River CWMA, Bugwood.org
Oriental bittersweet is a woody vine that escaped cultivation and spread throughout the temperate eastern US. Native to China, Korea, and Japan, Oriental bittersweet was introduced to North America in the mid 1860s as an ornamental. The vines girdle and smother trees and shrubs.
Common names: Oriental bittersweet, Asian bittersweet, climbing spindleberry
Scientific name: Celastrus orbiculatus Thunb.
Related species: C. scandens (native)
Oriental bittersweet is an early detection target species. Information on reporting Oriental bittersweet infestations.
Oriental bittersweet is a deciduous vine that grows up to 66' long. The vines climb by winding around a tree or other support structure. There are whitish, raised lenticels on the vine. The leaves are green then turn yellow in the fall. They are alternate and vary in shape from oblong to almost round. Leaf size is also variable from 2-5" long to 1.4-2" wide. The leaf margins have rounded teeth. There are separate male and female plants. Flowering occurs in the spring and flowers are arranged in clusters of 2-7 at the leaf axils. Each flower has 5 petals and 5 sepals. Fruits are round and change in color from green to bright red with a yellow capsule as they mature. Typical female plants can produce up to 370 fruits which ripen in the fall.
Oriental bittersweet is found in forested areas, field and forest margins, meadows, right-of-ways, fence rows, along waterways and in residential landscapes. This plant thrives in a range of soil types and light levels from full sun to shade.
Oriental bittersweet reproduces by seed and rhizome. The fruits are consumed then dispersed by birds and mammals and ingested seeds have a higher germination rate than seeds that fall to the ground. People move seed by using fruiting stems in flower arrangements. Oriental bittersweet is sometimes mistakenly labeled as American bittersweet then sold and planted.
Oriental bittersweet has spread throughout the temperate eastern US and Canada. The first confirmed Oriental bittersweet infestations in Minnesota were found, reported, and controlled in 2010 by the Minnesota Department of Transportation on their right-of-ways in the Twin Cities area. Tracing back these infestations, we learned that they were planted along fences by persons who thought they had planted American bittersweet. A large infestation of Oriental bittersweet has been confirmed in Winona, Minnesota.
Oriental bittersweet vines twine around trees and other supports resulting in girdled and smothered trees and shrubs. Entire plant communities may be overwhelmed by Oriental bittersweet. In addition, the added weight of the vines covered with snow and ice can break trees and shrubs. Oriental bittersweet outcompetes and displaces our indigenous American bittersweet to the point that Connecticut now lists the formerly common American bittersweet as a species of concern.
Avoid spreading Oriental bittersweet by learning to recognize it and not planting it. Do not collect and use the fruiting stems for ornamental purposes. Remove all infestations from your property. Bag or burn all fruit for disposal.
For all management options, infested sites will need to be monitored and treated repeatedly until the seedbanks are depleted.
Oriental bittersweet is a prohibited noxious weed on the eradicate list. This means that all of the above and below ground parts of the plant must be destroyed, as required by Minnesota Statutes, Section 18.78. Additionally, no transportation, propagation, or sale of these plants is allowed.
Minnesota Department of Agriculture (MDA), 625 Robert Street N, St. Paul, MN 55155-2538, firstname.lastname@example.org