| Criteria to Determine Invasive Status
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| Widespread and Invasive |
| Fanwort |
Cabomba caroliniana |
| Asiatic Bittersweet |
Celastrus orbiculatus |
| Autumn Olive |
Elaeagnus umbellata |
| Japanese Honeysuckle |
Lonicera japonica |
| Purple Loosestrife |
Lythrum salicaria |
| Japanese Knotweed |
Polygonum cuspidatum |
| Curly Pondweed |
Potamogeton crispus |
| Common Buckthorn |
Rhamnus cathartica |
| Multiflora Rose |
Rosa multiflora |
| Black Swallowwort |
Vincetoxicum nigrum |
| Restricted and Invasive |
| Tree of Heaven |
Ailanthus altissima |
| Garlic Mustard |
Alliaria petiolata |
| Porcelain-berry |
Ampelopsis brevipedunculata |
| Variable Water-milfoil |
Myriophyllum heterophyllum |
| Lesser Celandine |
Ranunculus ficaria |
| Watercress |
Rorippa nasturtium-aquaticum |
| Wineberry* |
Rubus phoenicolasius |
| White Swallowwort* |
Vincetoxicum rossicum |
| More Information Needed On It's Spread in RI |
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To be considered invasive in Rhode Island a species must:
- Not be indigenous to Rhode Island.
- Have naturalized.
- Have the biological potential for rapid and widespread dispersion and establishment.
- Have the biological potential for dispersing over spatial gaps away from the site of introduction.
- Have the biological potential for existing in high numbers away from intensively managed artificial habitats.
- Be widespread in Rhode Island or at least common in a region or habitat types in the state.
- Have numerous individuals in many populations.
- Be able to out-compete other species in the same natural community.
- Have the potential for rapid reproduction and establishment in natural communities.
- Two other categories indicate whether a species is "Widespread and Invasive" or "Restrictive and Invasive."
- To be considered "Widespread and Invasive," a species must be widespread in Rhode Island with many populations in minimally managed natural habitats.
- To be considered "Restricted and Invasive," a species must be common in at least part of the state or a particular habitat type(s in the state and with some populations in minimally managed natural habitats.
- A final set of criteria may indicate that a species is potentially invasive in Rhode Island: If a species meets the first five criteria but does not, at this time, meet Criteria 6 through 9 (all, it may be included as a "Potentially Invasive Species" if it meets at least one of Criteria 11 through 13. In the past some of these species have been considered invasive in Rhode Island at least in part because they are known to be invasive in other regions and thus expected to be so here.
- Have some populations in Rhode Island that have high numbers of individuals forming dense stands in minimally managed habitats.
- Have the potential, based on its biology and its colonization history in the northeast or elsewhere, to become invasive in Rhode Island.
- Be acknowledged to be invasive in nearby states but its Rhode Island status is unknown or unclear. This may result from a lack of field experience with the species or from difficulty in species determination or taxonomy.
Information adapted from the RIWPS Web Site 
