Minn. officials concerned about new invasive plant

Oriental bittersweet
A new invasive plant called Oriental bittersweet has made its way into Minnesota. It looks much like its cousin, the American bittersweet. The fruit of the Oriental bittersweet is released from yellow capsules on the vines, while the American is released from orange capsules.
MPR Photo/Elizabeth Baier

A new invasive plant called Oriental bittersweet has made its way into Minnesota this year. Infestations have been found in the Twin Cities metro area, as well as in southeastern Minnesota, near Winona.

The Oriental bittersweet looks much like its cousin, the American bittersweet. Both plants have a bright red fruit that prompts people to collect it this time of year for use in wreaths and other holiday decorations.

But the Oriental bittersweet is bad news for forest areas.

Monika Chandler, an invasive species coordinator for the Minnesota Department of Agriculture, says what makes the Oriental bittersweet such a threat is its vines. They can wrap around trees and strangle them. They also dominate the forest canopy.

"They shade the tree so that the tree doesn't get as much light. They shade the forest floor so that fewer plants can germinate," said Chandler. "And they also can add a lot of weight to the tops of the trees, and break the trees off in cases of high winds and ice storms."

Chandler says the infestation in Winona, the largest in the state so far, was confirmed in mid-November. She says officials with the agriculture department will meet with other agencies early next year to come up with a plan to contain and control this new invasive species.

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Invasive plant
The Oriental bittersweet, an invasive plant, has been found in Minnesota this year. The biggest threat is presents is its vines, which can wrap around trees and strangle them.
MPR Photo/Elizabeth Baier

"We're quite concerned about the Mississippi riverway, and having an invasive vine like this enter the riverway, because then it can really run unchecked in an area like the Mississippi River," she said.

Chandler says the best way to differentiate between the two species is their color. The fruit of the Oriental bittersweet is released from yellow capsules on the vines, while the American is released from orange capsules.

She says the invasive Oriental plant spreads when people transport the vines or seeds, or plant them on their property, mistaking them for the American bittersweet. Since the infestations are still limited, there's a chance to prevent it from spreading throughout the state.

In addition to the Winona infestation, the Minnesota Department of Transportation has been monitoring smaller Oriental bittersweet infestations in in Anoka, Dakota, Hennepin and Ramsey counties.