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. The 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 Current DISC Invasive Plant List Conclusion Document (January 2024)
DISC Invasive Plant List
Scientific and common names are based on: McAvoy, W.A. 2023. The Flora of Delaware Database. Delaware Division of Fish and Wildlife, Species Conservation and Research Program, Smyrna, Delaware.
| Species | Common Name |
|---|---|
| Acer palmatum | Japanese maple |
| Acer platanoides | Norway maple |
| Acorus calamus | European sweetflag |
| Ailanthus altissima | tree-of-heaven |
| Albizia julibrissin | silktree |
| Alliaria petiolata | garlic mustard |
| Alternanthera philoxeroides | alligatorweed |
| Ampelopsis glandulosa | porcelain-berry |
| Aralia elata | Japanese angelica tree |
| Artemisia vulgaris | mugwort |
| Arthraxon hispidus var. hispidus | joint-head arthraxon |
| Benthamidia japonica | Kousa dogwood |
| Berberis thunbergii | Japanese barberry |
| Broussonetia papyrifera | paper-mulberry |
| Cabomba caroliniana | Carolina fanwort |
| Cardamine impatiens | touch-me-not bittercress |
| Carex kobomugi | Asiatic sand sedge |
| Celasrus orbiculatus | Asian bittersweet |
| Cenchrus purpurascens | Chinese fountaingrass |
| Centaurea stoebe subsp. micranthos | spotted knapweed |
| Cirsium arvense | Canada thistle |
| Clematis terniflora | sweet autumn clematis |
| Commelina communis | Asiatic dayflower |
| Conium maculatum | poison-hemlock |
| Convolvulus arvensis | field bindweed |
| Echinochloa crusgalli var. crusgalli | barnyard grass |
| Egeria densa | Brazilian waterweed |
| Elaeagnus umbellata | autumn olive |
| Eragrostis curvula | weeping lovegrass |
| Euonymus alatus | winged euonymus |
| Euonymus fortunei | winter creeper |
| Fallopia japonica | Japanese knotweed |
| Ficaria verna subsp. verna | lesser celandine |
| Glechoma hederacea | ground ivy |
| Hedera helix | English ivy |
| Hedera hibernica | Atlantic ivy |
| Hemerocallis fulva | orange day-lily |
| Humulus scandens | Japanese hops |
| Hydrilla verticillata | hydrilla |
| Ilex crenata | Japanese holly |
| Iris pseudacorus | yellow flag |
| Koelreuteria paniculata | golden rain tree |
| Lespedeza cuneata | Chinese bushclover |
| Leucojum aestivum | summer snowflake |
| Ligustrum obtusifolium var. obtusifolium | border privet |
| Ligustrum sinense | Chinese privet |
| Ligustrum vulgare | common privet |
| Lonicera japonica | Japanese honeysuckle |
| Lonicera maackii | Amur honeysuckle |
| Lonicera morrowii | Morrow’s honeysuckle |
| Lonicera tatarica | Tartarian honeysuckle |
| Ludwigia grandiflora | erect water primrose seedbox |
| Ludwigia peploides var. glabrescens | creeping water primrose seedbox |
| Lysimachia nummularia | creeping jenny |
| Lythrum salicaria | purple loosestrife |
| Microstegium vimineum | Japanese stilt-grass |
| Miscanthus sinensis | Chinese silvergrass |
| Morus alba | white mulberry |
| Murdannia keisak | marsh dewflower |
| Myriophyllum aquaticum | parrot’s-feather water-milfoil |
| Myriophyllum spicatum | Eurasian water-milfoil |
| Narcissus pseudonarcissus | daffodil |
| Oplismenus undulatifolius | wavyleaf basketgrass |
| Pachysandra terminalis | Japanese pachysandra |
| Paulownia tomentosa | princess-tree |
| Perilla frutescens | perilla |
| Persicaria longiseta | longbristle smartweed |
| Persicaria perfoliata | mile-a-minute-vine |
| Phalaris arundinacea | reed canary-grass |
| Phellodendron amurense | Amur cork tree |
| Phragmites australis subsp. australis | European reed |
| Phyllostachys aurea | golden bamboo |
| Pinus thunbergiana | Japanese black pine |
| Prunus avium | sweet cherry |
| Prunus subhirtella | weeping Higan cherry |
| Pueraria montana var. lobata | kudzu |
| Pyrus calleryana | Bradford pear |
| Quercus acutissima | sawtooth oak |
| Reynoutria japonica var. japonica | Japanese knotweed |
| Rhamnus davurica | lance-leaf buckthorn |
| Rhodotypos scandens | black jetbead |
| Robinia pseudoacacia | white flowered locust |
| Rosa multiflora | multiflora rose |
| Rubus parvifolius | three-leaf blackberry |
| Rubus phoenicolasius | wineberry |
| Schoenoplectiella mucronata | alien bulrush |
| Stellaria media | common chickweed |
| Tripidium ravennae | Ravenna grass |
| Typha angustifolia | narrowleaf cattail |
| Urtica dioica subsp. dioica | stinging nettle |
| Viburnum dilatatum | linden viburnum |
| Viburnum plicatum | doublefile viburnum |
| Viburnum setigerum | tea viburnum |
| Viburnum sieboldii | Siebold’s viburnum |
| Vinca minor | common periwinkle |
| Vitex rotundifolia | beach vitex |
| Wisteria sinensis | Chinese wisteria |
DISC Invasive Plant Watch List
Scientific and common names are based on: McAvoy, W.A. 2023. The Flora of Delaware Database. Delaware Division of Fish and Wildlife, Species Conservation and Research Program, Smyrna, Delaware.
| Species | Common Name |
|---|---|
| Abies firma | Momi fir |
| Akebia quinata | five-leaf akebia |
| Buddleja davidii | butterfly bush |
| Corydalis incisa | purple corydalis |
| Deutzia crenata var. crenata | Deutzia |
| Fatoua villosa | mulberry weed |
| Galanthus nivalis | snowdrop |
| Lespedeza thunbergii | Thunberg’s bushcover |
| Lilium lancifolium | tiger lily |
| Lotus corniculatus | birds-foot trefoil |
| Mahonia bealei | Chinese mahonia |
| Malus toringo | Toringo crabapple |
| Pistia stratiotes | water-lettuce |
| Pourthiaea villosa | Asian photinia |
| Spirea japonica | Japanese spirea |
| Trapa natans | water chestnut |