Oriental Bittersweet – A Highly Invasive and Aggressive Vine

Oriental Bittersweet is an invasive climbing vine from Asia that can kill trees reducing our bio-diversity.  The Oriental Bittersweet vine will climb other plants, wrapping itself like twine.  Since this is a somewhat rigid woody vine that grips tightly, as the diameter of the tree increases it will crush and girdle itself against the vine.  Additionally, the Oriental Bittersweet will form a thick canopy, shading out the tree it climbed, and many other plants on the forest floor.  This horrible plant was released upon us like so many others, via exotic gardeners in the 1860’s.

 Oriental Bittersweet Facts

• Native to east Asia
• Without any control methods, Oriental Bittersweet will kill mature trees via girdling
• Oriental Bittersweet was introduced to North America as an ornamental plant in the 1860’s, unfortunately.
• The scientific name of Oriental Bittersweet is Celastrus orbiculatus

Other common names of Celastrus orbiculatus

• Asiatic Bittersweet
• Climbing Spindle berry
• Oriental Bittersweet
• Oriental Staff Vine
• Round-leaved bittersweet

How does Oriental Bittersweet kill trees and other vegetation?

The vine will wrap itself tightly around a tree in a coil / spiral manner.  As the vine is woody and tightly wraps itself, it will strangle the tree as the trunk tries to increase in diameter.

Additionally, trees and other vegetation can be killed by lack of sunlight.  The vine will make a thick canopy on top of the tree/shrub, out competing it for sunlight.  The lack of nutrients from photosynthesis will eventually kill the tree.

How does Oriental Bittersweet Spread?

Oriental Bittersweet spreads via rhizomes or seed.  Rhizome roots form thick colonies of the vine.  Because of birds, the seed is spread far and wide.  Also, since the fruits are so attractive, humans unwittingly spread this plant by using it in outdoor fall displays.

How to Control Oriental Bittersweet?

Mechanical Methods

For small infestations, hand pulling can be effective.  When the soil is somewhat moist, put on a pair of leather gloves pull!  Get a firm grip, and if the soil starts ripping up in front of you, keep going and try to get as much of the root as possible.  Roots should be left somewhere to dry, or disposed in the trash.  If you have a fire ring, or can burn them safely – do so.

Repeated cutting or mowing of Oriental Bittersweet can kill a plant.  But it is not a good idea (generally).  This is because when you cut it, the extensive root system will likely sprout new vines.  These aren’t always easy to see and can blend in with other vegetation.

When is it a good idea to cut Oriental Bittersweet?

If you have this plant growing within an isolated flower bed surrounded by lawn, then cutting can work, as there is limited space for new sprouts to escape being mowed.

Also, if you are clearing a forested area or tree of this vine, even if you are not prepared to treat the whole infestation, cutting the vines can have a positive effect for the tree they are strangling!  This is because they won’t leaf out in the Spring and starve the tree of sunlight.

Chemical Control for Oriental Bittersweet

Although I try to avoid herbicide use, I will use it on Oriental Bittersweet.  By cutting stems and painting with a small amount of systemic herbicide, you can kill this plant.  Glysophate (round up) or Stump Killer are effective.  Click here to go to our illustrated guide on killing woody vines, trees and stumps.

Oriental Bittersweet Identification / Physical Description

Oriental Bittersweet is a climbing vine that coils itself around something vertical (often trees/shrubs).  It has the ability to climb trees, fences, shrubs – almost any vegetation.  It can grow to over 90′ tall (30 m), and completely cover and shade out large, mature trees.  Generally though they are 10-60′ tall (3-20 m).

Stalk / Stem

The stalk of Oriental Bittersweet is woody and is found coiling, or growing in a spiral shape up a tree, shrub, fence post.  Additionally it can be found just forming a canopy on top of shorter exposed vegetation.  It can form very dense thickets that are hard to walk through in the forest.

Bark

The bark is rough textured when mature.  When younger, it is somewhat smooth and tan/reddish in color.

Leaves

The leaves are kind of shaped like a  spade (oval/orbicular), often with a prominent tip on the end.  It will be veined, with the veins running 30-45 degrees from the center and mirrored.  The margin/edge of the leaf will be round-serrated, or round-saw toothed.  The upper part of the leaf is a medium shade green, while the underside of the leaf is more pale-green in color.

Flower

Small, somewhat inconspicuous flowers are produced in late Spring to early Summer for about 2 weeks in duration.  They are small white flowers (1/4″-1/2″) with five petals.

The flowers will eventually produce bright red/orange fruits in the Fall that are about the size of a pea.  These are very noticeable as they contrast against the brown/green foliage.  The fruit will also look like it has just ‘burst’ or popped out of its leaf capsule.  As the leaves will still be around the fruit.

Root

The roots of this plant are shallow rhizomes approximately 3/4″ thick (9 mm), and very extensive in size/mass.  I’ve pulled root systems / rhizomes that were 10-20′ long, and branching (at least that is what I’ve observed).  The roots of Oriental Bittersweet are orange / orange-brown in color.

Growing Conditions

Seeing how horrible and invasive this plant is, it is not surprise that it is well equipped for growing almost anywhere.  It will grow in deeply shaded forests, woodland edges, open grass/prairies, along the edges of farm fields, and roadside ditches.

So, Oriental Bittersweet can germinate and grow in full sun or full shade and medium or balanced moisture.  Basically, where ever you can find Bush Honeysuckle or Garlic Mustard other highly invasive species), you can likely find Oriental Bittersweet.

Fauna

Bees pollinate the flowers in the Spring.  The fruits are eaten by a wide variety of birds.  Everything from the Bluebirds/Robins/Cardinals to quail and Turkey, with many others that I’ve not listed.

Pests and diseases

No significant pests or diseases in North America, unfortunately.

Want to learn about more Invasive Plants?  Click Here to see our other detailed write-ups and control methods.

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