Celastrus orbiculatus (Round-leaf Bittersweet)

Plant Info
Also known as: Oriental Bittersweet, Asian Bittersweet
Genus:Celastrus
Family:Celastraceae (Staff-tree)
Life cycle:perennial woody
Origin:Asia
Status:
  • Invasive - ERADICATE!
  • Noxious Weed
  • Prohibited or Restricted species
Habitat:part shade, sun; woodland edges, thickets, old fields
Bloom season:May - June
Plant height:10 to 60-foot vine
Wetland Indicator Status:GP: UPL MW: UPL NCNE: UPL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 5-petals Cluster type: panicle Cluster type: raceme

[photo of flowers] Clusters of up to 7 stalked flowers (frequently 3), forming in the leaf axils of this year's side branches of older woody stems, occasionally also at the tip of a branch. Flowers are ¼ to 1/3 inch across with 5 green to yellowish petals and 5 green sepals. Male and female flowers are typically on separate plants, rarely on the same plant and rarely a plant will have perfect flowers (having both male and female parts). Male flowers have 5 stamens with creamy white tips (anthers); female flowers have a stout style with a 3-lobed stigma at the top. Flowers are on a slender, hairless stalk.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

 [photo of leaves] Leaves are alternate, 2 to 5 inches long and 1½ to 3 inches inches wide, have rounded teeth around the edges, are smooth on the upper surface, and may have sparse hairs along the veins on the underside. The slender leaf stalk is about ¾ inch long.

[photo of leaves] Leaf shape is somewhat variable, nearly round to oval or may be broadest at the tip end. The tip is rounded, or with an abrupt sharp point, or with a short taper to a point. The base is rounded, slightly heart-shaped, or slightly tapering to the stalk. Woody branches are gray-brown to brown with scattered conspicuous white pores (lenticels); the trunk, which can be 4 inches in diameter, has more roughly textured bark. This vine has no tendrils; it twines around trees and other structures for support.

Fruit: Fruit type: berry/drupe Fruit type: capsule/pod

[photo of fruit] Fruit is round, about 1/3 inch across, initially green, the outer casing turning yellow in late summer then splits open to reveal a bright red, 3-sectioned berry-like fruit, each section containing 1 or 2 seeds.

Notes:

This, commonly known as Round-leaf Bittersweet or Oriental Bittersweet, is a Very Bad plant, brought into North America as an ornamental and escaped into the wild. It is a terrible pest plant in the eastern U.S. and was just getting started in Minnesota when we first published this in 2013. Now it's well established and spreading irrespective of its noxious weed status. It spreads by both seeds and rhizomes, suckering like mad and creating incredibly dense walls, blocking nearly all light from whatever used to grow beneath it. The vines wrap themselves around trees and can strangle them, or even bring them down from the sheer weight of its leafy arms.

Incredibly, it is still sold as nursery stock in some areas. It should be banned in the U.S., but there is too much money to be made selling “exotic” plants, so there really is no stopping it. In Minnesota it was initially listed as an Eradication species, meaning the MN Department of Agriculture (MDA) targeted it for extermination while it was still relatively few in number here. That was apparently a lost cause so it was downgraded to “prohibited control noxious weed”, which means it cannot be propagated or sold in the state and is supposed to be controlled to prevent spread, but I fear that is also a hopeless endeavor. Populations have been tracked on the Invasive Plant Atlas and EDDMaps.

When not flowering or fruiting, it is very difficult to distinguish from the native American Bittersweet (Celastrus scandens) but there are a number of differences to aid in a positive ID.

  • When flowering or fruiting, C. orbiculatus has mostly small clusters in the leaf axils of a branch where C. scandens will have one large cluster at the end of a branch.
  • C. orbiculatus flowers are typically greener with narrower petals than C. scandens.
  • The male flowers of C. orbiculatus have creamy white anthers where those of C. scandens are distinctly yellow.
  • The fruits of C. orbiculatus have a yellow casing, where fruits of C. scandens have an orange to red casing.
  • Newer woody stems of C. orbiculatus have obvious white lenticels, where C. scandens lenticels are less conspicuous.
  • C. orbiculatus leaves are generally rounder and proportionately broader than C. scandens , with C. scandens more finely serrated, but this is variable.
  • In early spring when plants are just starting to leaf out, C. orbiculatus leaves are mostly flat or folded in half, opening like a book, where C. scandens will have the leaf edges rolled up like a scroll, though leaves developing later in the season may not be so easily distinguished.

The images on this page show many of these comparisons.

The two species are apparently capable of hybridizing, but whether this actually occurs in the wild is unknown and there is very little information available on this subject. Buyer beware: American Bittersweet is also available in the nursery trade and some vendors advertise selling it, but turns out to be Round-leaf Bittersweet instead. This isn't necessarily intentional, but just shows that those selling it can't always tell the difference, either. Know your source!

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More photos

Photos by K. Chayka and Peter M. Dziuk taken in Ramsey County. Photos by Mark Wheeler taken in Washington County.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Mary K - Douglas County
on: 2016-10-28 08:50:01

Does Oriental Bittersweet leaves turn yellow in the fall? I may have American Bittersweet growing, but the leaves are very round with a pointed end. They have turned yellow for the fall.

Posted by: K. Chayka
on: 2016-10-28 09:13:51

I don't know what color leaves turn in fall, but do not use only the leaf shape to make an ID. Flowers or fruit will tell you for certain.

Posted by: Alexandra B - Minnetrista
on: 2017-08-30 11:07:52

Didn't look super close. but fruit is very orange. did not see a lot of it, it was growing among the sumac near little long lake in sandy soil, on a steep hillside above the road.

Posted by: K. Chayka
on: 2017-08-30 20:49:21

Alexandra, both the invasive Oriental bittersweet and the native American bittersweet have red-orange fruit, but the outer casing of the capsule is orange on the native and yellow on the invasive. Also, the arrangement is different, with the native fruits just at the tips of branches and the invasive in leaf axils as well as the tip. You need to take all those things into account when deciding whether it is the native or not.

Posted by: Taralyn Wesley - North branch
on: 2019-01-25 17:24:27

Hello, i noticed this plant while out collecting natural staining items. Is this plant poisonous? I did gather some up and plan on boiling to bring out the natural stain color. I can give you the whereabouts it was found if you are still trying to eradicate the plants.

Posted by: K. Chayka
on: 2019-01-25 18:39:33

Taralyn, you should contact the Dept of Ag with the location. Since this is an "eradicate" species in MN, someone from the agency has to inspect it first. Email: arrest.the.pest@state.mn.us

Posted by: Sonia Nunez - Minneapolis
on: 2020-05-16 07:09:51

I have a "lovely" vine of this eating my fence and trying to consume all around it. I purchased the house almost two years ago and am trying to cut this (and the Trumpet vine and all rest of the invasive plants in the garden) out, but obviously I'm having a great time in the fight... I am going to drill down in the stumps and put in some herbicide, but any other tips? Do I need to contact the state since this is in my yard?

Posted by: K. Chayka
on: 2020-05-16 07:17:43

Sonia, if you think you have Oriental bittersweet in your yard and would like a positive ID, contact the MN Dept of Ag. See Arrest the pest

Posted by: Mike - Bloomington
on: 2022-07-04 18:07:52

I found what looked like this plant growing very fast and trying to consume a pine tree that I planted five years ago in my native garden. I pulled it out, roots and all, but have no idea where it came from.

Posted by: Jessica Jackson - Moorhead
on: 2023-07-31 14:31:24

I have this growing on my garage. Started about 3 weeks ago already quadruple in size. No idea if this is invasive or not or if I should leave it. I didn't plants it.

Posted by: K Chayka
on: 2023-07-31 17:27:40

Jessica, the non-native bittersweet is highly invasive and there is no question it should be eradicated. However, to-date there have been no reports of it in western MN so it is more likely the native bittersweet, which is found across the state, is what volunteered in your yard. It can be a bit aggressive in cultivation but it's your choice whether to remove it.

Posted by: Marian Fischer - Waseca County, Iosco township
on: 2024-04-05 09:07:39

I suspect the woody sapling I pulled out of my flower border yesterday may be Oriental bittersweet. It's too early in the season to have leaves, but what caught my eye was the incredibly orange roots. When doing an internet search for "woodies" with bright orange roots, Oriental bittersweet came up. The sapling also has alternating leaf nodes. Should I send this sapling anywhere for identification?

Posted by: K Chayka
on: 2024-04-05 09:20:36

Marian, you could email photos to the Dept of Agriculture, who is responsible for invasive species monitoring and control in the state. See their fact sheet for more information.

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