A new National Park Service plant survey of the George Washington Memorial Parkway has documented 298 new vascular plants in Virginia, Maryland and Washington, D.C., bringing the known plants of the parkway to 1,313 taxa, representing 1,284 species. Seventeen may be the first records for Virginia, and 21 are the first records for Fairfax County.  

The survey includes trees, shrubs, vines, herbaceous plants, grasses, sedges, rushes and others. In the Mount Vernon area, it includes plants in the Belle Haven picnic area, Fort Hunt Park, the Dyke Marsh Wildlife Preserve and other sites along the parkway.

Brent Steury, NPS natural resources program manager and Mount Vernon resident, published the survey in Banisteria, the journal of the Virginia Natural History Society. 

In addition to the totals, Steury determined that 15 of the newly-documented taxa are listed by Virginia as rare in the state. Prior to this survey, only plants in Great Falls Park had been published. The study’s purpose was to inventory sites on the entire parkway not previously surveyed.  

Vascular plants transport water and food internally through tissues, like the “strings” of celery or the veins of leaves. “Plants are important because they produce oxygen, sequester carbon and are the base food for most biodiversity,” Steury said.

Twenty-nine percent of all plants along the parkway are not native, Steury found. These plants, usually called invasives, were most likely introduced by people, both intentionally and unintentionally.

“A big part of this study was to determine which species planted in the landscape are escaping into the environment,” Steury explained. He cites as examples, porcelainberry, English ivy and Japanese honeysuckle that have spread into natural areas.  

Invasive plants, have few controls or lack natural controls such an insects and disease to keep them in balance. Many invasives can out-compete native plants, form a monoculture, reduce biodiversity and destroy native habitats. Unlike invasives, native plants evolve over thousands of years with other species and provide habitat and food for wildlife species with which they have co-evolved. 

Several local groups and individuals are trying to control invasive plants on national park lands. The Mount Vernon Council of Citizen Association’s (MVCCA) Environment and Recreation Committee, the Friends of Dyke Marsh's “Weed Warriors”, and National Park Service staff over the last several years have attacked plants like bush honeysuckle, English ivy, garlic mustard, porcelain berry and multiflora rose. Teams have been working recently to remove bamboo from the west side of the Parkway near the overlook near Morningside Lane.

“People should not plant invasive species in their yards and could become a weed warrior to fight invasive species that have already escaped into GWMP natural areas,” advised Steury.

The George Washington Memorial Parkway, built as a memorial to the nation’s first President, consists of 7,374 acres in Virginia, Maryland and D.C. from Interstate 495 near McLean to the Mount Vernon Estate. It has Potomac River vistas, historic sites, natural areas and formal gardens.

The plant survey is titled “Additions to the Vascular Flora of the George Washington Memorial Parkway, Virginia, Maryland and the District of Columbia.”

Christina deMariano with the National Park Service and members of the Friends of Dyke Marsh work on invasive plants in the Dyke Marsh Wildlife Preserve every Thursday from 10 a.m. to 12 p.m. and welcome volunteers. Contact Christina at 703-289-2545 or Christina_Demariano@nps.gov for details.