What are invasive species?
Invasive species are plants, animals, and micro-organisms that are found outside of their natural range, and whose presence poses a threat to environmental health, the economy, or society (Government of Canada, 2004).
The Ontario Ministry of Resources and Forestry, in collaboration with Ontario non-profit organizations, is actively working to track and manage existing invasive species, while monitoring for the introduction of new species.
The following is a list of some of the invasive plants that can be found in Ontario today. For more information on these plants and how to manage them, check out our Best Management Practices, Grow Me Instead Guide, and Technical Documents, available through our Resources page.
The Aquatic Invasive Plant BMP (last updated in March 2025) contains identification, lookalikes, biology and life cycle, habitat, distribution, pathways of spread, impacts, and control for the following species:
• Brazilian Waterweed (Egeria densa)
• Curly-leaved Pondweed (Potamogeton crispus)
• European Frog-bit (Hydrocharis morsus-ranae)
• European Lake Sedge (Carex acutiformis)
• European Water Chestnut (Trapa natans)
• Eurasian Water-milfoil (Myriophyllum spicatum)
• Eurasian and Northern Milfoil hybrid (Myriophyllum spicatum × M. sibiricum)
• Fanwort (Cabomba caroliniana)
• Floating Primrose-willow (Ludwigia peploides)*
• Flowering Rush (Butomus umbellatus)
• Hydrilla (Hydrilla verticillata)
• Oxygen Weed (Lagarosiphon major)*
• Parrotfeather (Myriophyllum aquaticum)
• Phragmites (Phragmites australis subsp. australis)
• Purple Loosestrife (Lythrum salicaria)
• Rough Mannagrass (Glyceria maxima)
• Water Ferns – Azolla species
(Azolla filiculoides, A. cristata, A. pinnata)
• Water Hyacinth (Eichhornia crassipes)
• Water Lettuce (Pistia stratiotes)
• Watermosses – Salvinia species (Salvinia molesta, S. auriculata, S. minima, S. natans)
• Water Soldier (Stratiotes aloides)
• Yellow Floating Heart (Nymphoides peltata)*
• Yellow Iris (Iris pseudacorus)
(*) – Species is regulated under the Invasive Species Act (ISA) but is not listed on the Ontario Invasive
Aquatic Plant List.
