Chicago Botanic Garden

Plant Science — Conservation

Invasive Plants in the Chicago Region



Plants with a dash under the "alternatives" column are not commonly used ornamentally. You can find more information on alternatives at Illinois' Best Plants or

Species Common Name Status Alternatives
Alternanthera philoxeroides Alligator weed R ______
Azolla spp. Water fern R Lemna minor (lesser duck weed)
Butomus umbellatus Flowering rush R Juncus effusus (common rush), Sagittaria, Schoenoplectus americanus (bulrush)
Cabomba caroliniana Fanwort R ______
Eichhornia crassipes Water hyacinth R ______
Egeria densa Brazilian elodea R Elodea canadensis (water weed)
Hydrilla verticillata Hydrilla, water thyme R ______
Hydrocharis morsus-ranae European frog-bit R Native Nuphar (yellow pond lily) and Nymphaea (waterlily)
Ipomoea aquatica Water spinach R Justicia americana (American water willow)
Myriophyllum aquaticum Parrot feather R Elodea canadensis (water weed)
Myriophyllum spicatum Eurasian watermilfoil R Elodea canadensis (water weed)
Najus minor Toothed water weed R ______
Nasturtium officinale Watercress R ______
Nymphoides peltata Yellow floatingheart R Native Nuphar (yellow pond lily)and Nymphaea (waterlily)
Pistia stratiotes Water lettuce R ______
Potamogeton crispus Curlyleaf pondweed R ______
Salvinia minima Water fern R ______
Salvinia molesta Aquarium water moss R ______
Trapa natans European water chestnut R ______

Chicago Botanic Garden Conservation Science Department Status:

R = Remove as soon as possible, including all cultivars, and/or do not add to collection in future;
P = Phase out (species that pose a lesser invasive risk, form significant structural features in landscape, and will be time-consuming to replace will be phased out over a five- to ten-year period);
E = Evaluate species and cultivars, then remove invasive taxa;
W = Watch list (taxa not posing a serious invasive risk in the Chicago area currently, but may do so in the future).