Plants are festive but unwelcome

By Matt Gunderson
Globe Correspondent / December 9, 2010

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Every fall, Oriental bittersweet vines across Massachusetts sprout yellowish pods, festooned with orange and red berries. Over the years, the plant has proven irresistible to homeowners in the Bay State, who often display the vines in chandeliers or on their front doors as wreaths during the holiday season.

But Oriental bittersweet, while apparently harmless, has a darker side, and state and local conservation officials are urging residents not to use the plant or other invasive species in holiday decorations.

Although it has been in Massachusetts for over 100 years, the plant is considered an aggressive invasive species. Bittersweet curls around tree limbs and trunks, infesting, choking, and ultimately killing the trees that are its hosts.

State wildlife officials and local conservation agents worry that Oriental bittersweet, and another, less commonly used, ornamental plant, multiflora rose, will continue to spread across the state if people keep using the plants indiscriminately during the holidays.

Birds eat the berries from doorway holiday wreaths and scatter the seeds, allowing the invasive plants to spread more rapidly. The sale and importation of Oriental bittersweet and multiflora rose are both prohibited by Massachusetts in an effort to contain the problem.

Ted Elliman, vegetation management coordinator for the New England Wild Flower Society, based in Framingham, said bittersweet is already well established in Massachusetts and is spreading northward into Maine.

“I think there are quite a few people out there who aren’t aware of the environmental damage it causes but find it a very attractive plant,’’ Elliman said.

Carol Gumbart, Bolton’s conservation administrator, also said she has seen Oriental bittersweet wreaths on front doors around town this time of year.

Garden stores don’t sell the plant, but Paul Mancusco, a buyer for Mahoney’s Garden Center in Winchester, said customers have requested the vine around the holidays in past years. More recently, he has had fewer inquiries about the plant, making him wonder whether it’s becoming common knowledge that the vine is a habitat killer.

“Maybe people have gotten the message,’’ Mancusco said. “I think word is getting around.’’

Tim Simmons, a restoration ecologist for the Massachusetts Division of Fisheries and Wildlife, said some people are using American winterberry in decorations instead — a native plant with red berries — but that plant is in limited supply.

Simmons said the state’s woes with Oriental bittersweet are getting progressively worse, as the vine radiates out from its points of origin along the coastal regions of Massachusetts. He said he would be hard-pressed to find a city or town in the state that doesn’t have at least some sort of problem with the invasive vine.

“It’s been around so long, it’s in every town and county,’’ said Simmons.

For years, town officials in Groton have battled to keep bittersweet from taking over conservation land on Chicopee Row, the site of a historic barn, said Barbara Ganem, the town’s conservation administrator.

Several trees, their limbs weighing heavily with bittersweet vines, surround the barn, and a committee that oversees the land, the Williams Barn Committee, is mulling different options for getting rid of the plant, including regular cutting and herbicide treatment.

Bolton’s Bower Springs Conservation Area has been fighting back Oriental bittersweet for years, and various groups in town have tried fruitlessly to eradicate the vines, which have killed several trees on the bucolic conservation area near the Harvard town line, said Gumbart.

“We’ve had a variety of people trying to work on that over the years, but it’s a significant problem,’’ said Gumbart. “We really haven’t been able to control it.’’

Local Scout groups have tried to clip the vines back, but the plant has proved too resilient, said Gumbart, and continues to grow back annually. The trees killed by the aggressive vine still stand on the property as a nesting place for birds.

Ganem said the ecological hazards extend beyond trees. The vines create a shroud overhead in tree branches, blocking light to the undergrowth. That prevents many native plants from growing and essentially destroys the ecology of a woodland area, she said.

“It out-competes a lot of native plants that normally grow in a location,’’ said Ganem.

In an effort to contain the problem statewide, the Division of Fisheries and Wildlife focuses its efforts on areas where there are small, newer infestations of Oriental bittersweet or where the vine is threatening a valuable natural resource, said Simmons. Limited resources of the state agency prevent the state from attempting to eliminate the vine from Massachusetts, or places where the vine is already well established, he explained.

“We have to take a much more targeted approach,’’ said Simmons. “Some of the infestations are so large that no one can afford to take them out.’’