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

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.