Invasive Bittersweet (Black Diamond) Traditional Cache

This Bittersweet is obviously invasive, which makes it more likely to be the unwanted Oriental kind, but not necessarily so. They hybridize! It’s very hard to tell the difference, especially at this time of year. BYOP.

This from: Minnesota Department of Natural Resources:

Oriental Bittersweet Description:

Appearance: Deciduous vine that grows up to 66 ft. long. Vines climb by winding around a tree or other support structure.

Leaves: Alternate, simple, vary in shape from oblong to almost round. Leaf size is also variable from 2-5" long to 1.4-2" wide. Leaf margins have rounded teeth.

Flowers: There are separate male and female plants. Flowering occurs in the spring and flowers are arranged in clusters of 2-7 at the leaf axils. Each flower has 5 petals and 5 sepals. Flowers are small and greenish-yellow.

Fruit: Fruits are round and change in color from green to bright red with a yellow capsule as they mature. Typical female plants can produce up to 370 fruits which ripen in the fall.

Roots: Underground rhizomes spread and can send up new plants.

To distinguish from the native vine, American bittersweet (Celastrus scandens):

    •    American bittersweet has orange capsules around red fruits, Oriental bittersweet has yellow capsules around red fruits.

    •    American bittersweet flowers and fruits are only found at the terminal ends of stems, Oriental bittersweet flowers and fruits are found all along the stem at leaf axils.

    •    Leaf shape is highly variable and not a good characteristic for distinguishing American vs. Oriental bittersweet.

Ecological Threat:

    •    Highly invasive in forests in the Eastern US. Vines girdle trees as they climb to dominate the canopy and shade the understory, reducing and preventing the growth of other plant species. Oriental bittersweet still has a limited distribution in Minnesota at this time. By detecting Oriental bittersweet populations early and rapidly treating infestations in Minnesota, we may be able reduce the impact this species has in Minnesota.

    •    At times, the weight of Oriental bittersweet vines in the canopy can break trees, especially with the additional weight of snow and ice.

    •    Oriental bittersweet outcompetes and displaces American bittersweet (which is native to Minnesota) to the point that Connecticut now lists the formerly common American bittersweet as a species of concern. Additionally, by hybridizing with American bittersweet, Oriental bittersweet causes further loss of American bittersweet populations.

    •    Oriental bittersweet is a MDA Prohibited Noxious Weed (Eradicate List) in Minnesota meaning that above and below ground parts of the plant must be destroyed.  Additionally no transportation, propagation, or sale of Oriental bittersweet and its cultivars (including 'Diana', 'Hercules', 'Indian Mix', 'Indian Brave', and 'Indian Maiden') is allowed. Report Oriental bittersweet by emailing "Arrest the Pest" arrest.the.pest@state.mn.us or calling 651-201-6684 (metro) or 1-888-545-6684 (toll-free)

Control Methods:

Prevention:

Oriental bittersweet has a limited distribution within Minnesota so there is still a chance to prevent it from spreading throughout the state. People move seed by using fruiting stems in flower arrangements. Oriental bittersweet is sometimes mistakenly labeled as American bittersweet then sold and planted. Avoid planting Oriental bittersweet.

Mechanical:

For small populations, pull or dig up plants. Regular, weekly mowing will control Oriental bittersweet, but less frequent mowing may result in suckering from the roots

Chemical:

Cut stems and apply herbicide (such as glyphosate or triclopyr) to the cut stem.

Native Substitutes:

    •    American (climbing) bittersweet (Celastrus scandens) and its cultivars

 This from: Great Lakes Science Center in Ann Arbor, MI

American and Oriental Bittersweet Identification

Invasive species are one of the greatest threats to native ecosystems. They can crowd out native species and change the natural nutrient cycling processes that take place in ecosystems.

There is a lot of interesting and helpful information at their link:<https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev3_017307.pdf>

Unfortunately I couldn’t copy the fascinating page 2, that shows pictures and characteristics, with arrows, how to separate the Oriental (unwanted) version from the American (desired) one.

Worst Invasive Plants from "the Spruce" 

False/American bittersweet (Celastrus scandens):

if you have false bittersweet on your landscape, you are fortunate: it's a great fall foliage plant

it is not destructive

nor is it an invasive plant.

Oriental bittersweet (Celastrus orbiculatus):

Oriental bittersweet, while beautiful, is destructive and difficult to eradicate, being one of the worst of North America's exotic invasive plants

like Japanese knotweed, it spreads underground via rhizomes

The cache is a tied in, camoed, “small” pill bottle, that has to be pushed hard to open and close.Please keep track of the contents, including the 2 rubber bands. The second one to make a neck on the baggie, so it’s easier to pull out of the bottle. No tweezers, please. Don't forget: BYOP!