Officials ask Minnesotans to watch for invasive plant

Posted at 6:00 AM on December 14, 2010 by Elizabeth Baier

(MPR Photo/ Elizabeth Baier)

A new invasive plant has made its way into the state this year.

It's called the Oriental bittersweet, and it looks much like its cousin, the American bittersweet.

Infestations have been found in the Twin Cities metro area, as well as in southeastern Minnesota, near Winona. Agriculture officials are urging Minnesotans to avoid using the vine as a holiday decoration this season.

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.

What makes the Oriental bittersweet such a threat is its vines, said Monika Chandler, an invasive species coordinator for the Minnesota Department of Agriculture. 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," Chandler said. "They shade the forest floor so that fewer plants can germinate. 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."

The infestation in Winona was confirmed in mid-November, according to Chandler. It's the largest in the state so far. She said 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.

"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.

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

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 Anoka, Dakota, Hennepin and Ramsey counties.