Common Name: Asian bittersweet, Oriental bittersweet
Scientific name: Celastrus orbiculatus
Identification: Asian bittersweet is a perennial, twining woody vine that loses its leaves annually and has male and female flowers on separate plants (i.e., it is dioecous). Stems can grow up to 60’ long with older stems reaching up to 4” in diameter with slightly ridged dark to medium brown bark. Leaves are 2-5” long, glossy, and oblong to round with a pointed or rounded tip, and are toothed along the leaf edges. Leaves are arranged alternately along the stem. Clusters of small green flowers (¼– ⅓” in diameter) form where the leaf meets the stem, blooming in May to June. Fruit are spherical, ⅓” in diameter and develop between July and October. Asian bittersweet fruit are green when young, then ripen to yellow before splitting open at maturity to reveal a red-orange capsule around the seed. Split fruit often remain on plants into winter. (Dirr 1998, Hilty 2007)
Look-alikes: Asian bittersweet is very similar looking to the native and closely related American bittersweet (C. scandens). At maturity, the flowers and fruit all along the stem helps distinguish Asian bittersweet from American bittersweet which only forms flowers and fruit at the end of each stem. Yellow fruit capsules also help distinguish it from American bittersweet, which has orange fruit capsules. Telling the two species apart prior to maturation is very challenging. According to Sarver et al. (2008), the emerging leaves of the invasive species are folded in half along the midrib, while the emerging leaves of the native species curl inward toward the midrib. The two species can hybridize, making identification even harder.
Asian bittersweet has been observed throughout the U.S. and Canadian portions of the Great Lakes Basin. It is reported in every U.S. state east of the Mississippi River with the exception of Florida and is common in the Midwest, New England, and the Mid-Atlantic. USDA reports Asian bittersweet as being hardy to a minimum temperature of -38oF (Zone 3a). Particularly dense populations of Asian bittersweet can be expected in areas where the species has been or still is popular as an ornamental landscape plant.
Additional invasive species distribution data for specific Great Lakes jurisdictions are available via:
Seed is spread over distance by birds. Humans also contribute to its spread by planting mislabeled American bittersweet (Zaya et al. 2017) and using fruiting branches in dried flower arrangements or wreaths displayed or composted outside.
Asian bittersweet occurs most frequently in forest edges, open woodlands, fields, hedgerows, coastal areas, and disturbed lands. However, its tolerance of shade allows it to invade interior forest areas too.
Oriental bittersweet outcompetes native species by growing up and over native vegetation, blocking access to light, girdling trees, and making them more susceptible to ice and storm damage. Oriental bittersweet can establish large populations relatively quickly due to its high seed production and root suckering. Ecologists are also concerned by Oriental bittersweet’s ability to hybridize with American bittersweet, diluting the native species gene pool. Hybrid seedlings show many of the same invasive traits as the Asian species (Pooler et al. 2002). Over time, it is feared that hybridization and competition for resources will dramatically reduce American bittersweet distribution.
Asian bittersweet has historically been valued as an ornamental plant due to its climbing habit, large quantity of bright fruit in winter, and low maintenance requirements. Stems with fruits are also sold as components of dried flower arrangements or winter wreaths. Asian bittersweet was also planted extensively for highway landscaping, wildlife forage, and erosion control. Although invasive species regulations in many states in the U.S. have diminished its popularity, retailers – particularly online retailers – often sell the invasive species mislabeled as the native American bittersweet (Zaya et al. 2017).
None. Asian bittersweet is dioecious and male cultivars do not produce fruit. However, they can still pollinate female Asian bittersweet and American bittersweet plants.
Please see our Landscape Alternatives pages for more information about how the WIGL Collaborative selected alternatives.
|Alternatives for Asian bittersweet
Common name (Latin name)
for arbor, trellis
|American bittersweet (Celastrus scandens)a
‘Bailumn’ AUTUMN REVOLUTION™
|Woodbine, Virgin’s bower (Clematis virginiana)||✔||✔|
|Virginia creeper (Parthenocissus quinquefolia)||~d||✔||✔|
|Dutchman’s pipe (Aristolochia macrophylla)||✔||✔|
|Trumpet honeysuckle (Lonicera sempervirens)||✔||~c||✔|
|American wisteria (Wisteria frutescens)
|Climbing hydrangea (Hydrangea anomala subsp. petiolaris)||~d||✔|
~ = trait is somewhat present but not as pronounced as in check-marked examples
a Asian bittersweet is often mislabeled as its native cousin and sold by nurseries. If purchasing American bittersweet, it is very important to seek a reputable nursery (preferably one that specializes in woody and/or native plants) and ask questions to confirm it is, in fact, native bittersweet.
b This cultivar is capable of self-pollination for fruit production unlike most other bittersweet varieties.
c Trumpet honeysuckle fruit are colorful, but may not last into winter.
d Virginia creeper and climbing hydrangea are clinging vines; they do best on solid surfaces like walls and wooden fences.
Green = native to all or part of the Great Lakes Basin
Yellow = native to North America but not to the Great Lakes
Blue = not native but not invasive
The following is a brief overview of management techniques shown to be effective on Asian bittersweet. For more detailed information on how to use these techniques, please visit our Management and Control page. For technical assistance on managing woody invasive species, please get in touch with a local cooperative invasive species management group.
Timing and spread concerns: Early detection is an advantage in managing any invasive species. Whenever possible, individual plants should be controlled before they are able to fruit in order to prevent spread. If control is undertaken after plants have fruited, it is best not to remove the plants from the site to avoid spreading seed.
Physical control: Asian bittersweet plants can be pulled or dug up as long as the roots are completely removed. However, removal of a large root system can be difficult. Incomplete removal leads to extensive regrowth, which can result an overall increase in the population (Fryer 2011). Due to these concerns, physical removal is not recommended for large or established populations. Mowing of low-growing plants can be effective but only when the mower is set low enough to completely defoliate the plants and is repeated every two weeks during the growing season. A prescribed fire regime can kill seedlings and prevent seeds from germinating; land managers have had success in controlling seedling and small bittersweet stems (<1/8” diameter) with repeated annual prescribed fire in spring (Midwest Invasive Plant Network). However, prescribed fire is not recommended for established bittersweet populations as it tends to trigger extensive regrowth and suckering in mature plants, making infestations worse. If pursuing a combined approach as described below, cutting or mowing is more effective than burning as preparation for herbicide treatment (Pavlovic et al. 2016).
Chemical control and combined approaches: Foliar, cut stump, and stem injection herbicide treatments are effective. Foliar spray may be the most feasible control method for a dense infestation of vines that have not climbed into desirable trees that would be damaged by herbicide. It is effective when plants are actively growing and fully leafed out. It is often most effective when combined with cutting or mowing with foliar herbicide applied to the resulting regrowth later in the season. Cut stump and stem injection treatments can be applied year-round outside of early spring and are also effective. In all cases, herbicide should be selected carefully based on site conditions, and label directions read and followed carefully.
With any treatment, it will be necessary to monitor for and treat regrowth and new seedlings in subsequent years.
- Fryer, J.L. 2011. Celastrus orbiculatus. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. 10/23/19.
- Hilty, J. 2017. Oriental bittersweet. In: Illinois Wildflowers. 10/23/2019.
- Midwest Invasive Plant Network. Invasive Plant Control Database. Oriental bittersweet case study. 10/23/19.
- Pavlovic, NB, Leicht-Young, SA, and Grundel, R. 2016. Oriental bittersweet (Celastrus orbiculatus): Spreading by fire. Forest Ecology and Management 364: 183–194.
- Pooler, MR, Dix, RL, and J Feely. 2002. Interspecific hybridizations between the native bittersweet, Celastrus scandens, and the introduced invasive species, C. orbiculatus. Southeastern Naturalist 1(1): 69-77.
- Sarver, M, Treher, A, Wilson, L, Naczi, R and FB Kuehn. 2008. Oriental bittersweet and American bittersweet. In: Mistaken Identity? Invasive Plants and Their Native Look-alikes. Delaware Department of Agriculture. 24-25.
- Zaya, D, Leicht-Young, S, Pavlovic, N, Hetrea, C, & M Ashley. 2017. Mislabeling of an invasive vine (Celastrus orbiculatus) as a native congener (C. scandens) in horticulture. Invasive Plant Science and Management 10(4):313-321.
Photo Credit: Leslie J. Mehrhoff, UConn, via bugwood.org