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Invasive Vines Have a Chokehold on a D.C. Park

By Adrian Higgins
Thursday, November 8, 2007

When Robert Woods Bliss and Mildred Barnes Bliss decided to give up their Georgetown mansion and the surrounding gardens and landscape of Dumbarton Oaks, they donated the house and its grounds to Harvard University. They handed the outlying 27 acres -- a stream valley and woodland formed to provide a pastoral counterpoint to the formal garden terraces -- to the National Park Service.

Almost seven decades later, Dumbarton Oaks remains a world-class garden. Beyond its perimeter, however, Dumbarton Oaks Park is almost unrecognizable as a designed landscape. Paths are worn to mud by dog walkers and joggers, weeds clutter the stream bank and the lines between woodland and meadow have been blurred by saplings and other wildlings.

But the most fearsome evidence of the park's decline is in a clearing between the stream and the distant high wall of the Safeway on Wisconsin Avenue: An area of perhaps three acres or more is smothered in unchecked mounds of invasive vines, including giant climbing tear thumb (named for the barbs along its stems), porcelainberry and a species of wild grape. The infestation forms six-foot-high mounds until it reaches a tree or the far walls, where it climbs. The vines have smothered a 100-foot ailanthus tree in the center of the vista.

The scene is a testament to the power of weedy vines left to their own devices for so long. The vastness of the green blanket is strange to behold, and the idea of it is shocking, here in the heart of the capital.

For more than 10 years, park users and supporters have tried to get the Park Service to work with them in restoring Dumbarton Oaks Park, but efforts have stalled. The park is under the jurisdiction of Rock Creek Park but does not receive separate funding despite efforts to get it, said Cindy Cox, deputy superintendent of Rock Creek Park.

"We did a cultural landscape report in 2000 in order to get us started, and we have done stabilization work incrementally since then. We have a preservation maintenance plan, but we haven't taken any huge steps," she said. Cox said there was no endowment to maintain the property when it was donated. "It's such a beautiful place, and all of us cringe to not have it in perfect condition," she said.

Last year, a Washington-based preservation group, the Cultural Landscape Foundation, listed the park as one of 19 historic landscapes at risk of being lost. A sign at the park's entrance announces "restoration in progress" and urges users to stay on the trails. Apart from some snow fencing, there is little evident work underway. If there is reason for optimism, it is that other historic landscapes have been brought back from the brink in recent years. Charles Birnbaum, the foundation's president, noted that neglected portions of New York's Central Park and Boston's Emerald Necklace, both the work of Frederick Law Olmsted, have been redeemed. Dumbarton Oaks is considered the masterpiece of America's pioneering female landscape architect, Beatrix Farrand.

Birnbaum said Dumbarton Oaks Park will need a major storm-water management remedy before the state of the plantings and the many surviving rustic structures is addressed. "And that's a large funding issue," he said. Cox said the park service has stabilized the architectural features, which include dams, arbors and stone benches.

The park's viney moonscape provides a reminder that gardens are among the most fleeting of art forms but that, ironically, some plants linger and thrive as ghosts of the original creation.

At the Fells, the summer estate of statesman John M. Hay and his descendants in Newbury, N.H., a nonprofit group stepped in to save the house and its gardens. In the intervening 13 years, an army of 150 volunteers has reclaimed an impressive rock garden, moss garden, perennial border and other features developed primarily by Hay's son, Clarence, and Clarence's wife, Alice, in the first three decades of the 20th century.

Among the invasive echoes of the Hays' garden were widespread plantings of the perennial bellflower ( Campanula rapunculoides) and a rock garden thug, bloodred cranesbill ( Geranium sanguineum).

The bellflower, in particular, was "all over the site," said Jeff Good, landscape manager. "It likes the sun, the shade, and it's taprooted," making it hard to pull in a garden where pesticides are not used.

His crews also had to tackle woody weeds planted by the Hays as ornamentals, particularly barberries and the burning bush or winged euonymus.

Once the invasives are controlled and gardens restored, a lingering dilemma for stewards of historic gardens is whether to keep original specimens of invasive plants that were planted in a period when invasiveness was far less a consideration than was ornament. The Hay garden has two 70-year-old specimens of winged euonymus, which Good is keeping. At Dumbarton Oaks, garden superintendent Gail Griffin removed the porcelainberry that had been used to decorate the stairs to the Fountain Garden -- too late to stop its frightening spread in the park.

Old plant lists reveal another aspect of our forebears' gardening: The plants at hand were limited compared with the array of perennials, herbs, shrubs, trees and vines now at hand after decades of breeding.

Alcatraz, the 22-acre island in San Francisco Bay, was used as a military prison and then a federal penitentiary before it was closed and the island designated a national recreation area. The Garden Conservancy, working with the National Park Service, has identified five gardens created by inmates and prison officers and is in the fourth year of restoration.

The first year was spent trying to beat back the weeds planted as ornamentals, particularly English ivy first planted to hide concrete railings, Japanese honeysuckle and the Himalayan blackberry brambles that covered the entire island. The brambles are traced to a single bush planted in the garden of the associate warden, said Carola Ashford, project manager for the Garden Conservancy.

The cleanup has allowed plants installed in the 1930s to grow and bloom for the first time in decades, including Mediterranean plants and succulents that survived the Rock's thin soil and harsh conditions. The warden had asked for recommendations from San Francisco area horticultural societies, Ashford said.

Many bulbs have flowered for the first time in years, Ashford said, including crocosmias, freesias, Dutch iris and grape hyacinth. Roses, pelargoniums, fuchsias and various succulents, freed from the brambles, have come back to life like Sleeping Beauty, an alluring prospect for those who one day see a Dumbarton Oaks Park returned to its glory.

"It's interesting how it can be so ephemeral and yet so persevering," Ashford said.

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