American Bittersweet vs Oriental Bittersweet
These species, one native, and one introduced and widely considered invasive, are similar in appearance and easily confused. They can be reliably distinguished by flower and fruit cluster arrangement, and sometimes, by fruit capsule color, leaf shape, or leaf serration pattern. Both species are variable in appearance, and looking at multiple characteristics is important. These species also can potentially hybridize; the rate of hybridization in the wild is unknown.
American Bittersweet (Celastrus scandens) | Oriental Bittersweet (Celastrus orbiculatus) |
A vine with a wide distribution in northeastern and central North America, declining in many areas to due competition from the introduced Celastrus orbiculatus. | Introduced from East Asia, and widely considered an invasive plant. Out-competing the native Celastrus scandens in many areas. |
 Fruits arranged in large terminal clusters, only at the end of each branch. Photo © aarongunnar, CC BY 4.0. |  Fruits arranged in small clusters coming out of each axil, along the entire length of the branch. Photo © Katja Schulz, CC BY 4.0. |
 Leaves much narrower than long. Usually long-acuminate. Photo © Dawn Littleton, CC BY 4.0. |  Leaves nearly as wide as long, look broad and rounded. Can be long-acuminate, but tip is often short and stubby. Photo © Wouter Koch, CC BY 4.0. |
 Serrations on leaf margin are usually more sharply-pointed. Photo © Quinten Wiegersma, CC BY 4.0. |  Serrations on leaf margins are usually more rounded. Photo © andrew_garn, CC BY 4.0. |
 Capsule enclosing fruit is orange to red, averaging darker and more reddish. Photo © Quinten Wiegersma, CC BY 4.0. |  Capsule enclosing fruit is yellow to orange, averaging lighter and more yellowish. Photo © Even Dankowicz, CC BY 4.0. |
References & External Resources
These short lists show only links helpful for ID. For a complete list of references and resources also covering other aspects of ecology, visit the links section of the full article on each plant, which is the first entry here.
