Invasive Plants of Rhode Island


Invasive species have come into a region from some other part of the world. However, the term "invasive" means different things to different people. To some, an invasive perennial or woody plant is one that spreads; to others it is a plant that spreads and is also vigorous and difficult to control.

Either concept is valid. The operative word is "spreading" - the plants spread beyond where they are wanted and are difficult to control. The mechanisms by which invasive plants spread include both roots and seeds. Sometimes, spreading roots can be used to advantage to cover rough, denuded areas to control erosion. Unfortunately, in gardens the root-spreading plants will take over and kill species that are less vigorous.

Root-spreading plants can be controlled by cultivating, weeding out seedlings, planting them in containers, and systemic herbicides.

There are lists of invasive plants, but when using these it should be noted that not all species or cultivars of a listed genus are invasive. Each list has its own criteria and all lists should be used only as a guide to be consulted before buying or planting. Also, there are lists of Potentially Invasive Plants and these include plants that are suspect because they are being found in unexpected places relative to known plantings.

How You Can Take Action


Teach your family, friends and neighbors about the negative ecological effects of invasive species.


Be an informed consumer and use native, non-invasive plant species in your home gardens. Also, encourage your local nurseries to offer a wider variety of these plants.


Learn more about non-invasive landscape alternatives, how to control specific invasive plants, and selecting native plants by visiting the websites recommended on this site.

Seek Advice

Ask at your local nursery or contact the URI Gardening Hotline to find out the best ways to remove invasive species from your landscape.

Good Gardening

Prevent seed spread by deadheading flowers, that is, cutting off flowers immediately after they have faded.

Clean Environment

Clean your boat and motor thoroughly after leaving a body of water - this will prevent the spread of aquatic invasive species.

(Adapted from Rhode Island's Natural Heritage Under Siege: Meeting the Challenge of Invasive Species, Publication #4015 of the Rhode Island Agricultural Experiment Station)

Facts about Destruction and Loss

" The two greatest threats to biological diversity around the world are habitat loss/destruction and the presence of invasive species.

" Nearly half of the plants and animals on the U.S. Endangered Species List are at risk because of invasive species.

" Invasive species can enter a region through many routes, including global transport of goods and livestock, nursery and seed trades and other agricultural activities, the shipping industry, aquarium and pet trades, recreational boating, aquaculture, and tourism.

" Loss of biological diversity can mean that ecological processes are changed, affecting such vital activities as food production, the maintenance of water quality, and health care. Lowered biological diversity also decreases our ability to "mine" species for new food crops, medicines, and industrial materials.

" Invasive species are costly: there are annual losses of $137 billion estimated for the U.S. alone. The losses affect agriculture, industry, forestry, commercial fishing, recreation, and water supplies.

(Adapted from Rhode Island's Natural Heritage Under Siege: Meeting the Challenge of Invasive Species, Publication #4015 of the Rhode Island Agricultural Experiment Station)

Useful Websites is the gateway to Federal efforts concerning invasive species. It provides information about the impacts of invasive species, the government's response, species profiles, and links to agencies and organizations that deal with invasive species issues. It is also the website for the National Invasive Species Council.

The National Park Service The National Park Service site offers fact sheets on "Alien Plant Invaders of Natural Areas" and includes detailed information on control and alternative landscape species.

The Nature Conservancy The Nature Conservancy's site, called The Invasive Species Initiative, has an image library and detailed information on many aspects of invasive plant issues.

The New England Wild Flower Society The New England Wild Flower Society site - "Sources of Invasive Plant Information" - has lists of resources for further information.

The Invasive Plant Atlas of New England IPANE (The Invasive Plant Atlas of New England) is a site developed by the University of Connecticut which lists related websites.

The Rhode Island Natural History Survey The Rhode Island Natural History Survey provides ecosystem science and information.

The Rhode Island Wild Plant Society The Rhode Island Wild Plant Society site has a full plant library, including invasive species.

Potentially Invasive (in Connecticut)

Adapted from Non-Native Invasive and Potentially Invasive Vascular Plants in Connecticut, University of Connecticut

Acer ginnala (Amur Maple)
Acer platanoides (Norway Maple)
Acer pseudoplatanus (Sycamore Maple)
Aegopodium podagraria (Goutweed)
Aira caryophyllea (Silver Hairgrass)
Allium vineale (Wild Garlic)
Amorpha fruticosa (False Indigo)
Anthraxon hispidus
Berberis vulgaris (Barberry)
Bromus tectorum (Drooping Brome-grass)
Butomus unbellatus (Flowering-rush)
Cirsium arvense (Canada Thistle)
Callitriche stagnalis
Datura stramonium (Jimsonweed)
Elaeagnus angustifolia (Russian Olive)
Elsholtzia ciliate (Elsholtzia)
Euphorbia esula (Leafy Spurge)
Geranium nepalense (Nepalese Crane's-bill)
Glechoma hederacea (Gill-over-the-ground)
Kochia scoparia (Summer Cypress)
Ligustrum obtusifolium (Border Privet)
Ligustrum ovalifolium (California Privet)
Ligustrum vulgare (European Privet)
Lonicera maackii (Amur Honeysuckle)
Lonicera tatarica (Tatarian Honeysuckle)
Lonicera xylosteum (European Fly-honeysuckle)
Lychnis flos-cuculi (Ragged Robin)
Lysimachia nummularia (Moneywort)
Marsilea quadrifolia (Water Shamrock)
Miscanthus sinensis (Eulalia)
Myosotis scorpioides (Forget-me-not)
Myriophyllum aquaticum (Parrotfeather)
Nelumbo lutea (American Water Lotus)
Najas minor (Eutrophoc Water Nymph)
Ornithogalum umbellatum (Star of Bethlehem)
Paulownia tomentosa (Empress Tree)
Phalaris arundinacea (Reed Canary Grass)
Poa compressa (Canada Bluegrass)
Polygonum cespitosum
Polygonum perfoliatum (Mile-a-minute Vine)
Populus alba (While Poplar)
Pueraria lobata (Kudzu Vine)
Ranunculus ficaria (Lesser Celandine)
Rosa rugosa (Japanese Rose)
Rumex acetosella (Sheep Sorrel)
Silphium perfoliatum (Cup Plant)
Solanum dulcamara (Climbing Nightshade)
Valeriana officinalis (Garden Heliotrope)
Veronicda beccabunga (Brooklime)

Selection of Invasive Species in Rhode Island

From Rhode Island's Natural Heritage Under Siege: Meeting the Challenge of Invasive Species, Publication #4015 of the Rhode Island Agricultural Experiment Station

Acer platanoides (Norway Maple)
Ailanthus altissima (Tree of Heaven)
Alliaria petiolata (Garlic Mustard)
Ampelopsis brevipedunculata (Porcelain-berry)
Berberis thunbergii (Japanese Barberry)
Cabomba caroliniana (Fanwort)
Celastrus orbiculatus (Asiatic Bittersweet)
Centaurea nigra (Black Knapweed)
Elaeagnus umbellata (Autumn Olive)
Euonymus alatus (Burning Bush)
Frangula alnus (Glossy Buckthorn)
Ligustrum species (Privet)
Lonicera japonica (Japanese Honeysuckle)
Lonicera morrowii (Morrow Honeysuckle)
Lonicera tatarica (Tatarian Honeysuckle)
Lonicera x (Bella Bella Honeysuckle)
Lythrum salicaria (Purple Loosestrife)
Myriophyllum heterophyllum (Variable Water-milfoil)
Phragmites australis (Common Reed)
Polygonum cuspidatum (Japanese Knotweed)
Potamogeton crispus (Curly Pondweed)
Rhamnus cathartica (Common Buckthorn)
Rosa multiflora (Multiflora Rose)
Vincetoxicum nigrum (Black Swallowwort)