Oriental bittersweet (Celastrus orbiculatus), also known as Asiatic or round-leaved bittersweet, is a shade tolerant woody vine native to eastern China, Korea, and Japan. It grows quickly and will invade forests, open woodlands, grasslands, roadsides, and fencerows. Birds eat its berries and spread the seeds, which further disperses the plant into new areas. Oriental bittersweet will completely cover and shade out native plants. It is even capable of wrapping so tightly around trees that it kills them. As stands of Oriental bittersweet grow denser and invade the canopy level, their weight alone can cause trees to blow over in high winds.
Habitat: Commonly found along forest edges, in open woodlands, and in early successional areas but is shade tolerant and can spread from the edges into forested areas as well.
Hardiness: Zone 4
Mature Shape: Vine that can be up to 60 feet long and 5 inches in diameter; may become shrub-like as it spreads
Leaves: Simple, alternate, 2-5 inches long, finely toothed, glossy, rounded with long tip; leaves turn yellow in the fall and stay on the vine late into the season
Flowers: small, greenish-yellow with 5 petals; grow in clusters at the leaf axils
Fruits: Initially greenish-yellow berries in the summer, turning to red, yellow, and orange in the fall. Fruits grow along the stem of the plant, distinguishing it from native bittersweet.
Flowering Dates: May-early June
American bittersweet (Celastrus scandens) is a native form of bittersweet that grows in the same habitat as Oriental bittersweet. American bittersweet flowers and fruits appear at the tips of the branches rather than along the stems at the leaf axils as in Oriental bittersweet. For more information on differentiating between American and Oriental bittersweet download the USGS American and Oriental Bittersweet Identification guide. Oriental bittersweet poses a threat to native bittersweet as it out-competes and hybridizes with it.
Control Methods
Small patches of Oriental bittersweet can be removed by pulling plants out by the roots and removing them from the area. This should be done before fruiting to prevent distribution of seeds. If fruiting has already occurred it is necessary to put any pulled vines in a bag and leave the bags in the sun to kill the seeds. See our Chemical Control of Unwanted Vegetation article for specific herbicides and application methods.
