Aquatic Plants in Trade

Although relatively harmless when confined to an aquarium or backyard water garden, invasive aquatic plants can cause problems when introduced into a natural waterway. This can happen in several ways, such as when water gardens are flooded by heavy rains or a hobbyist dumps unwanted plants into a local lake. Invasive plants can displace native ones, which are important sources of food and shelter for wildlife. They can also affect water chemistry and flow, block drainage pipes, and hinder commercial and recreational fishing. Impacts like these are becoming widespread in aquatic and wetland habitats throughout North America.

Illinois-Indiana Sea Grant worked with the Indiana Department of Natural Resources, the aquatic plant industry, academia, state agencies, and non-governmental organizations to develop a science-based risk assessment tool for aquatic plants that are found in trade. Using this tool, Indiana designated 28 aquatic plants as prohibited effective January 1, 2012. Following Indiana’s lead, the Illinois Department of Natural Resources added most of these same species to Illinois’ injurious species list. It is now illegal to buy, sell, or transport these species in Indiana and Illinois (see table below).

Retailers and hobbyists can help support the intent of these rules—which is to protect our natural areas from the harm caused by invasive species—by learning how to identify these prohibited plants. Plants at times are sold under an incorrect name or are misidentified, so it’s important that those working with aquatic plants know what to look for. Click on the plant names below for identification tips and to learn more about each species.

State Prohibited Scientific Name Common Name(s)
IL, IN Azolla pinnata mosquito fern
IL, IN Butomus umbellatus flowering rush
IL, IN Caulerpa taxifolia caulerpa or Mediterranean killer algae
IL, IN Egeria densa Brazilian elodea, Brazilian waterweed, anacharis, or egeria
IL, IN Eichhornia azurea anchored water hyacinth
IL, IN Hydrilla verticillata hydrilla or water thyme
IL, IN Hydrocharis morsus-ranae European frogbit or common frogbit
IL, IN Hygrophilia polysperma miramar weed, Indiana swampweed, or hygro
IL, IN Ipomoea aquatic Chinese waterspinach or swamp morning-glory
IL, IN Iris pseudacorus yellow flag or tall yellow iris
IL, IN Lagarosiphon majo oxygen weed or African elodea
IL, IN Limnophila sessiliflora Asian marshweed or ambulia
IL, IN Monochoria hastata Monochoria, arrowleaf, or false pickerelweed
IL, IN Monochoria vaginalis heartshape or flase pickerelweed
IL, IN Myriophyllum aquaticum parrot feather or parrot feather watermilfoil
IL, IN Myriophyllum spicatum Eurasian watermilfoil
IL, IN Najas minor brittle naiad or brittle water nymph
IL, IN Nymphoides peltata yellow floating heart
IL, IN Ottelia alismoides duck lettuce
IL, IN Potamogeton crispus curlyleaf pondweed
IL, IN Sagittaria sagittifolia arrowhead
IL, IN Salvinia auriculata giant salvinia
IL, IN Salvinia biloba giant salvinia
IL, IN Salvinia herzogii giant salvinia
IL, IN Salvinia molesta giant salvinia
IL, IN Sparganium erectum exotic bur-reed
IL Stratiotes aloides water soldier
IL, IN Trapa natans/i> water chestnut
IN Typha angustifolia narrow-leaf cattail

To learn more about invasive aquatic species in our waterways, visit our AIS page.

To learn more about invasive aquatic plants, visit:
University of Florida - Center for Aquatic and Invasive Plants
U.S. Geological Survey - Nonindigenous (Non-native) Aquatic Species

To purchase or download AIS materials on aquatic plants in trade, visit the Prairie Rivers Institute page -


Pat Charlebois
Aquatic Invasive Species Coordinator

Greg Hitzroth
Aquatic Invasive Species Outreach Specialist

Illinois-Indiana Sea Grant
Purdue University
195 Marsteller Street
West Lafayette, IN 47907-2033
University of Illinois Extensio
Sea Grant
Purdue University