Non-Native Invasive Plants

Other Websites

Mid-Atlantic Early Detection Network—track infestations of non-native invasive plants

Plant Invaders of Mid-Atlantic Natural Areas

Rock Creek Park

Volunteer with Rock Creek Park

Rock Creek Conservancy

Dumbarton Oaks Park Conservancy

Unfortunately, Rock Creek Park is home to more than 200 species of plants that are not native to the eastern United States, yet have made themselves at home in the natural communities of the park.

Explore this page:

Rock Creek Park's Least Wanted

list of commonly seen invasive plants in Rock Creek ParkList of Rock Creek Park's Non-Native Invasive Plants

Click on highlighted plants in the list to see photos and dig deeper. Learn about species that take priority at the park for removal.

non-native invasive plant collagePhoto album of Rock Creek Park's Non-Native Invasive Plants

Click on the title to see a flickr album of Rock Creek Park's "least wanted."

back to top

Non-Native Invasive Plants Harm Natural Communities

Non-native invasive plants are an enormous problem because they can take over habitat needed by native plants. (Read about the ways non-native plants make life difficult for native plants in Ecology Basics.)

Old, hollow trees are good habitat for barred owl nests, but choking vines can topple them prematurely.
Photographer: Julie McCall
Non-native invasive plants often create problems for native animals as well. For instance, many lowland forests at Rock Creek host cavity-nesting owls, woodpeckers and other animals in standing dead trees. In many areas, including some near Dumbarton Oaks, porcelain-berry vines have smothered the vegetation, toppling dead and weak trees, and destroying habitat for cavity-nesting animals.

In Rock Creek Park, non-native invasive plants are most prolific along roads, trails and waterways (where they are probably easily dispersed), and in clearings, meadows, and successional forests. Although some can grow in the forest shade, many prefer more sunlight, and hence are commonly found in sunny or edge habitats (such as the forest edge along trails, providing some sun, some shade). Invasive plants at Rock Creek are possibly the greatest threat to the ecological well-being of the two natural communities where the soils are most fertile and moist, the Basic Mesic Hardwood Forest, and the Tuliptree Small-stream Floodplain Forest. They are least often found in the driest upland forests because most of them prefer fertile soils and moisture.

back to top

Where Do Non-Native Invasive Plants Come From?

Many non-native plants that make good groundcover become weedy headaches well beyond the owners' property lines.
Photographer: Matt Jones
Coming from places as far flung as England, Japan, and Iran, many non-native invasive plants were brought to the United States in the nursery trade as desirable landscaping plants. Unfortunately, many are still sold at local nurseries and planted in gardens and backyards. Ecobit: Go Native

Not all ornamental plants are a problem, but some are prone to spreading beyond the garden borders, such as the ones listed here. Certain characteristics that may make them valuable to gardeners (prolific flowering, colorful clusters of berries, fast-growing groundcover, or hardiness) may also make them aggressive invaders or naturalizers, easily reproducing and thriving in the wild, with competitive advantages over many native plants. Ecobit: Don’t Let Your Ivy Climb

In Rock Creek Park, many non-native invasive plants originated as

  • Historic plantings to beautify D.C.
  • Ornamental plantings from neighboring residential gardens, or from former private estates like Dumbarton Oaks, the Peirce Nursery, and orchards that are now part of the park. Ecobit: Escaped Art
  • Dumping of plant debris by neighbors and landscape contractors
  • Agricultural fields and pastures upstream

Many caught a ride into the park as seeds or plant parts via:

  • Floodwaters
  • Fill dirt used in construction in the park or adjacent areas
  • Tire treads of cars
  • Horses’ hooves, hikers’ boots, dogs’ paws
  • Wind
  • Droppings from birds and other animals who ate their berries
  • Bird feathers, animal coats

Once in the park, they continue to spread!

back to top

Where Do They Grow at Rock Creek Park?

Knowing something about the growing conditions a particular non-native invasive plant can tolerate will help you predict where you might find the plant at Rock Creek Park—and which natural communities it might threaten.

Habitat Preferences for Some Non-Native Invasive Plants at Rock Creek Park

In the following lists, the asterisk* indicates a non-native plant.

Shade tolerant or semi-tolerant:

oriental bittersweet*, autumn-olive*, English ivy*, garlic mustard*, Japanese barberry*, Japanese honeysuckle*, linden arrow-wood*, … and many other non-native plants

back to top of section

Requires more direct sunlight during part or all of its lifecycle:

princess-tree*, tree-of-heaven*, … and many other non-native plants

back to top of section

Tolerates either shade or full sunlight:

Japanese honeysuckle*, Japanese hop*, linden arrow-wood*, porcelain-berry*, winter creeper*

back to top of section

Fire-adapted (can survive or leave surviving offspring after some degree of fire):


back to top of section


Most non-native species in the park

back to top of section

Germinates quickly on disturbed land sites:

princess-tree*, tree-of-heaven*, ...and many other non-native species in the park

back to top of section

Tolerates nutrient-poor, acidic soil:

autumn-olive*, princess-tree*, winged burning-bush*

back to top of section

Prefers nutrient-rich soil:

garlic mustard*, Japanese stiltgrass*, porcelain-berry*, … and many other non-native plants

back to top of section

Flood-tolerant (can survive or leave surviving offspring after some degree of flooding):

Japanese knotweed*, Japanese stiltgrass*, lesser celandine*

back to top of section


autumn-olive*, princess-tree*, tree-of-heaven*, winged burning-bush*

back to top of section

Putting It All Together

Explore the Stewardship & Ecological Threats page of any of Rock Creek Park's natural communities to see which non-native invasive plants are among the biggest troublemakers there. (Find links under Learn More.) Read up on the Physical Setting of that natural community.

Now that you know something about their habitat preferences, can you see why those non-native plants are successfully making inroads in that community?

back to top

What Is the National Park Service Doing?

The Park Service is giving priority to finding and eradicating infestations by "new" species of non-native plants—new to Rock Creek Park, that is. This is part of an Early Detection and Rapid Response strategy, to try to stop the spread of non-native invasives before they get out of hand. The plants targeted are nicknamed EDRR species. Ecobit: Early Detection Rapid Response Plants

Rock Creek Park staff, in collaboration with partners and trained volunteers, are actively removing these and many other non-native invasive plants from previously selected areas. They use a variety of methods of removal.

Civic groups who partner with Rock Creek Park to tackle the very big challenge of non-native invasive plants include: Rock Creek Conservancy, Dumbarton Oaks Park Conservancy, and Casey Trees.

back to top

You Can Make a Difference!

Interested in helping keep Rock Creek Park’s natural communities healthy?

  • When you're visiting Rock Creek Park in Washington, D.C., you can help keep its natural communities healthy by being observant and sharing what you see with park staff. Ecobit: An Extra Set of Eyes
  • Consider volunteering!
      • Find opportunities to volunteer with Rock Creek Park.
      • Team up with Rock Creek Conservancy, a citizen-based, non-profit organization that hosts volunteer restoration and education events for the benefit of the lands and waters of Rock Creek.
      • Team up with Dumbarton Oaks Park Conservancy, a citizen-based, non-profit organization that focuses on the restoration of a 27-acre historic gem in partnership with Rock Creek Park.
      • Take a Non-Native Invasive Plant Removal class at Casey Trees to learn how to identify species of non-native, invasive plants in Washington, D.C.

      Make a difference close to home!

      back to top