The threatening species list describes plants that have become invasive in our area, albeit less aggressively than the plants on either the “Top Threat” or “High Threat” lists. Many of the plants listed below have been used historically for ornamental landscapes, and in some cases are still planted today. We’ve broken the list down into three parts, prioritizing the most commonly planted species. ISN recommends against planting or fostering any of the threatening species in home landscapes, to reduce risk both to our region’s natural areas and to the birds and butterflies that rely on native plants for their survival, as well as to reduce costs to control plants as they spread.
This list will adapt and grow over time, since non-native plants themselves adapt to their new surroundings. On average, one in ten non-native imports naturalizes, and one in one hundred becomes invasive, from which we can draw two critical conclusions — 1) continued importation of non-native species guarantees new future invasive threats, and 2) 90% of the non-native species that have been imported have not shown signs of becoming invasive, leaving a wide array of planting options available to community members. However, ISN strongly recommends the use of regional native plants for ornamental landscapes, and further recommends fostering native plants in degraded areas to enhance natural competition against invasive plants.
| Invasive Plants Common to Ornamental Landscapes |
| Common Name | Latin Name | Type |
|---|---|---|
| amur maple | Acer ginnala | Tree |
| Norway maple | Acer platanoides | Tree |
| chocolate-vine | Akebia auinata | Vine |
| porcelain berry | Ampelopsis brevipedunculata | Vine |
| common barberry | Berberis vulgaris | Shrub |
| butterfly bush | Buddleja davidii | forb |
| lily-of-the-valley | Convallaria majalis | Forb |
| burning bush (aka winged wahoo) |
Euonymus alatus (including “compacta”) | Shrub |
| wintercreeper | Euonymus fortunei | Vine |
| tall fescue | Festuca arundinacea | Grass |
| sweet woodruff | Galium odoratum | Forb |
| English ivy | Hedera helix | Vine |
| orange day lily | Hemerocallis fulva | Forb |
| yellow flag iris | Iris pseudacorus | Forb |
| border privet | Ligustrum obtusifolium | Shrub |
| common privet | Ligustrum vulgare | Shrub |
| forget-me-not | Myosotis scorpioides | Forb |
| Austrian pine | Pinus nigra | Tree |
| Scotch pine | Pinus sylvestris | Tree |
| callery pear | Pyrus calleryana | Tree |
| black jetbead | Rhodotypos scandens | Shrub |
| Japanese spiraea | Spiraea japonica | Forb |
| wayfaring tree | Viburnum lantana | Shrub |
| European highbush cranberry | Viburnum opulus | Shrub |
| bigleaf periwinkle | Vinca major | Vine |
| periwinkle | Vinca minor | Shrub |
| Invasive Plants Occasionally/Historically Planted in Ornamental Landscapes |
| Common Name | Latin Name | Type |
|---|---|---|
| Snow-on-the-Mountain (aka goutweed) |
Aegopodium podagraria | Forb |
| tree-of-heaven | Ailanthus altissima | Tree |
| false indigo | Amorpha fruticosa | Shrub |
| smooth brome | Bromus inermis | Grass |
| celandine | Chelidonium majus | Forb |
| queen-anne’s-lace | Daucus carota | Forb |
| great hairy willow-herb | Epilobium hirsutum | Forb |
| spindle tree | Euonymus europaea | Shrub |
| cypress spurge | Euphorbia cyparissias | Forb |
| meadow fescue | Festuca pratensis | Grass |
| common St. John’s-wort | Hypericum perforatum | Forb |
| kalopanax | Kalopanax septemlobus | Tree |
| golden archangel | Lamiastrum galeobdolon | Forb |
| everlasting pea | Lathyrus latifolius | Forb |
| European fly honeysuckle | Lonicera xylosteum | Shrub |
| birdfoot trefoil | Lotus corniculatus | Forb |
| money plant | Lunaria annua | Forb |
| white mulberry | Morus alba | Tree |
| perilla mint | Perilla frutescens | Forb |
| lady’s thumb | Polygonum persicaria | Forb |
| white poplar | Populus alba | Tree |
| Lombardy poplar | Populus nigra var. italica | Tree |
| rough-fruited cinquefoil | Potentilla recta | Forb |
| sweet cherry | Prunus avium | Tree |
| perfumed cherry | Prunus mahaleb | Tree |
| sawtooth oak | Quercus acutissima | Tree |
| lesser-celandine | Ranunculus ficaria | Forb |
| black locust | Robinia pseudoacacia | Tree |
| white willow | Salix alba | Tree |
| crack willow | Salix fragilis | Tree |
| basket willow | Salix purpurea | Shrub |
| bouncing bet | Saponaria officinalis | Forb |
| common tansy | Tanacetum vulgare | Forb |
| white clover | Trifolium repens | Forb |
| Chinese elm (aka lace bark elm) |
Ulmus parvifolia | Tree |
| Siberian elm | Ulmus pumila | Tree |
| mullein | Verbascum thapsus | Forb |
| Invasive Plants that arrived through agriculture or as weedy tag-alongs |
| Common Name | Latin Name | Type |
|---|---|---|
| velvet leaf | Abutilon theophrasti | Forb |
| quack grass | Agropyron repens | Grass |
| non-native amaranth species | Amaranthus spp. | Forb |
| common burdock | Arctium minus | Forb |
| yellow rocket | Barbarea vulgaris | Forb |
| roving bellflower | Campanula rapunculoides | Forb |
| bitter cress | Cardamine impatiens | Forb |
| spotted knapweed | Centaurea maculosa | Forb |
| mouse-ear chickweed | Cerastium fontanum | Forb |
| lamb’s quarters | Chenopodium album | Forb |
| chicory | Cichorium intybus | Forb |
| field bindweed | Convolvulus arvensis | Forb |
| crown vetch | Coronilla varia | Forb |
| orchard grass | Dactylis glomerata | Grass |
| jimsonweed | Datura stramonium | Forb |
| queen-anne’s-lace | Daucus carota | Forb |
| Chinese yam | Dioscorea oppositifolia | Vine |
| common teasel | Dipsacus fullonum | Forb |
| cut-leaved teasel | Dipsacus laciniatus | Forb |
| Indian strawberry | Duchesnea indica | Forb |
| barnyard grass | Echinochloa crusgalli | Grass |
| white bedstraw | Galium mollugo | Forb |
| avens | Geum urbanum | Forb |
| ground ivy | Glechoma hederacea | Forb |
| motherwort | Leonurus cardiaca | Forb |
| silky bush-clover | Lespedeza cuneata | Forb |
| butter-and-eggs | Linaria vulgaris | Forb |
| white sweet clover | Melilotus alba | Forb |
| yellow sweet clover | Melilotus officinalis | Forb |
| timothy | Phleum pratense | Grass |
| English plantain | Plantago lanceolata | Forb |
| common plantain | Plantago major | Forb |
| Canada bluegrass | Poa compressa | Grass |
| tall or common buttercup | Ranunculus acris | Forb |
| curly dock | Rumex crispus | Forb |
| bladder campion | Silene cucubalus | Forb |
| white catchfly | Silene pratensis (lychnis alba) | Forb |
| bittersweet nightshade | Solanum dulcamara | Forb |
| perennial sow thistle | Sonchus arvensis (s. uliginosus) | Forb |
| common chickweed | Stellaria media | Forb |
| common dandelion | Taraxacum officinale | Forb |
| field hedge parsley | Torilis arvensis | Forb |
| Japanese hedge parsley | Torilis japonica | Forb |
| red clover | Trifolium pratense | Forb |
| cow-vetch | Vicia villosa | Forb |