Non-native Plants

What are non-native plants?

Invasive exotic plants are species that aggressively compete with and crowd out native plants. The loss of native plants has a huge impact on the health of the ecosystem. Animals lose food and habitat. Biodiversity declines. Groundwater levels are reduced. Soil becomes less fertile. And you may not be able to enjoy the park the same way if invasive non-native species spread unchecked.

Examples

 

Asiatic bittersweet

NPS

Asiatic bittersweet

A woody vine with bright orange berries, Asiatic bittersweet (Celastrus orbiculatus) is originally from east Asia. It weakens and kills trees and shrubs by strangulation - twining and climbing around them and preventing their absorption of light, air, and sap. Trees heavily matted with bittersweet vines are very susceptible to wind and ice damage. Many afflicted trees stand in Rock Creek Park.

 

Porcelainberry

NPS

Porcelainberry

A northeast Asian vine, porcelainberry (Ampelopsis brevipedunculata) kills native plants in the same ways bittersweet does. It thrives on the fringes of disturbed natural areas like the long boundary of Rock Creek Park in Washington, DC, outcompeting native species for water and nutrients. Its berries, which resemble porcelain beads and thus make it popular with landscapers, change color from white to a series of pastel shades of yellow, lilac, and green before finally turning blue and purple.

 

Bush Honeysuckle

NPS

Bush honeysuckle

Various species of bush honeysuckle (Lonicera spp.) came to America from Europe and Asia beginning in the mid-1800's. Most varieties have white flowers, although some boast pink or crimson blooms and even fragrance. Bush honeysuckles can quickly invade and overtake an area, creating dense stands that threaten native plants by decreasing available light and depleting soil moisture and nutrients.

 

Purple Loosestrife

NPS

Purple loosestrife

Originally from Asia, the tall, showy flower spikes of purple loosestrife (Lythrum salicara) can be found in at least 40 of the United States. Gardeners who enjoy planting it often don't realize how quickly and thoroughly it can damage wetland ecosystems--naturalists consider a single plant an infestation. Nicknamed the "Purple Plague," purple loosestrife is a particular problem at Kenilworth Aquatic Gardens in Washington, DC, the only national park devoted to water plants.

 

Other non-native species

• Autumn olive (Elaeagnus umbellata)
• Beefsteak plant (Perilla frutescens)
• Black swallow-wort (Cynanchum louiseae)
• Chinese privet (Ligustrum sinense)
• Chinese wisteria (Wisteria sinensis)
• Chinese yam (Dioscorea polystachya)
• Chocolate vine (Akebia quinata)
• Common barberry (Berberis vulgaris)
• Common periwinkle (Vinca minor)
• Doublefile viburnum (Viburnum pliicatum f. tomentosum)
• English ivy (Hedera helix)
• European privet (Ligustrum vulgare)
• Garlic mustard (Alliara petiolata)
• Ground-ivy (Glechoma hederacea)
• Holly osmanthus (Osmanthus heterophyllus)
• Incised fumewort (Corydalis incisa)
• Indian strawberry (Duchesnea indica)
• Japanese angelica tree (Aralia elata)
• Japanese barberry (Berberis thunbergii)
• Japanese honeysuckle (Lonicera japonica)
• Japanese hop (Humulus japonicus)
• Japanese knotweed (Polygonum cuspidatum)
• Japanese maple (Acer palmatum)
• Japanese snowball (Viburnum plicatum)
• Japanese snowbell (Styrax japonicus)
• Japanese stiltgrass (Microstegium vimineum)
• Jetbead (Rhodotypos scandens)
• Kudzu (Pueraria montana var. lobata)
• Leatherleaf mahonia (Mahonia bealei)
• Lesser celandine (Ranunculus ficaria)
• Linden arrow-wood (Viburnum dilatatum)
• Mile-a-minute weed (Polygonum perfoliatum)
• Multiflora rose (Rosa multiflora)
• Norway maple (Acer platanoides)
• Orange daylily (Hemerocallis fulva)
• Oriental false hawksbeard (Youngia japonica)
• Pale swallow-wort (Cynanchum rossicum)
• Princess-tree (Paulownia tomentosa)
• Silktree (Albizia julibrissin)
• Sweet cherry (Prunus avium)
• Sweet mock orange (Philadelphus coronarius)
• Tree-of-heaven (Ailanthus altissima)
• Wavyleaf basketgrass (Oplismenus hirtellus ssp. undulatifolius)
• White mulberry (Morus alba)
• Wine raspberry (Rubus phoenicolasius)
• Winged burning-bush (Euonymus alatus)
• Winter creeper (Euonymus fortunei)
• Winter-flowering cherry (Prunus subhirtella)
• Yellow archangel (Lamiastrum galeobdolon)
• Yoshino cherry (Prunus x yedoensis)

 

What can I do to help?

• Volunteer at Rock Creek Park.
• Help one of Rock Creek Park's partner organizations
• Report non-native plant infestations

 

Learn More

• 

  Nature

  Learn more about the natural side of Rock Creek Park

• 

  Animals

  What animals live in the Rock Creek Park?

• 

  Plants

  What grows in Rock Creek Park?