Plants
Plants on the DISC list included species that are non-native to Delaware, have the potential for widespread dispersal and establishment, can out-compete other species in the same area, and have the potential for rapid growth, high seed or propagule productions and establishment in natural areas. Each species was chosen by a committee of experts in environmental science and botany after an intensive environmental assessment.
The first Delaware Invasive Species Council (DISC) assessment of invasive plants was conducted in 2003, and followed protocol developed by NatureServe. A second assessment was done in 2006, following the same protocol. After the 2006 assessment, DISC developed three invasive categories – widespread and invasive, restricted and invasive, and restricted and potentially invasive. In 2019, DISC recognized that a revision of the 2006 list of invasive plants was needed, and that the NatureServe protocol should be modified to make it more relative to the state of Delaware. This current assessment is based on this modified protocol and intended for educational purposes
The protocols are documented in the Plant Species Assessment Protocol document.
Based on the expert assessments, an I-Rank, or invasive rank was determined based on expert responses denoting the level at which a species is invasive in the identified geographic area, in this case, the state of Delaware. These ranks are categorized by high, medium, low, and insignificant. If a species was ranked as high, medium, or low, they are deemed invasive to some degree by the experts and; therefore, are included in the current iteration of the DISC list of Invasive Plant Species. Species ranked as insignificant, were added to the DISC Watch List and will be reevaluated in two years when the list will again be revised. Additionally, for future revisions to the list, selected species thought to be invasive in Delaware will also be evaluated. In contrast to the 2006 DISC list of invasive plants, the new list includes only two categories – invasive and watch list. Below are the results.
Download the DISC Invasive Plant List Conclusion Document Here
DISC Invasive Plant List
| Species | Common Name |
|---|---|
| Acer palmatum | Japanese maple |
| Acer platanoides | Norway maple |
| Acorus calamus | European sweetflag |
| Ailanthus altissima | Tree of heaven |
| Alliaria petiolata | Garlic mustard |
| Ampelopsis glandulosa | Porcelain berry |
| Berberis thunbergii | Japanese barberry |
| Celasrus orbiculatus | Oriental bittersweet |
| Centaurea stoebe subsp. micranthos | Spotted knapweed |
| Clematis terniflora | Japanese Clematis |
| Elaeagnus umbellata | Autumn olive |
| Eragrostis curvula | Weeping lovegrass |
| Euonymus alatus | Winged euonymus |
| Euonymus fortunei | Wintercreeper |
| Fallopia japonica | Japanese knotweed |
| Ficaria verna | Lesser celandine |
| Hedera helix | English ivy |
| Hemerocallis fulva | Orange daylily |
| Hydrilla verticillata | Hydrilla |
| Iris pseudacorus | Yellow flag iris, Water flag |
| Koelreuteria paniculata | Golden raintree |
| Leucojum aestivum | Summer snowflake |
| Ligustrum vulgare | European privet |
| Lonicera japonica | Japanese honeysuckle |
| Lonicera maackii | Amur honeysuckle |
| Lonicera morrowii | Morrow’s honeysuckle |
| Lonicera tatarica | Tartarian honeysuckle |
| Lysimachia nummularia | Creeping jenny |
| Lythrum salicaria | Purple loosestrife |
| Microstegium vimineum | Japanese stilt grass |
| Miscanthus sinensis | Chinese silvergrass |
| Murdannia keisak | Marsh dewflower |
| Pachysandra terminalis | Japanese pachysandra |
| Persicaria perfoliata | Mile-a-minute |
| Phalaris arundinacea | Reed canarygrass |
| Phragmites australis subsp. australis | European reed |
| Pinus thunbergiana | Japanese black pine |
| Pyrus calleryana | Callery pear |
| Rosa multiflora | Multiflora rose |
| Rubus phoenicolasius | Wineberry |
| Viburnum dilatatum | Linden arrowwood |
| Viburnum sieboldii | Siebold’s viburnum |
| Vinca minor | Lesser periwinkle |
| Wisteria sinensis | Chinese wisteria |
DISC Invasive Plant Watch List
| Species | Common Name |
|---|---|
| Buddleja davidii | Butterfly bush |
| Ilex crenata | Japanese holly |
| Lespedeza thunbergii | Thunberg’s bushcover |
| Lilium lancifolium | Tiger lily |
| Lotus corniculatus | Bird’s foot trefoil |
| Mahonia bealei | Leatherleaf mahonia |
| Quercus acutissima | Sawtooth oak |
| Spirea japonica | Japanese spirea |
| Viburnum plicatum | Japanese snowball |
| Viburnum setigerum | Tea viburnum |