Species At Risk

Ogden’s Pondweed

(Potamogeton ogdenii)


Ogden’s Pondweed


Ogden’s Pondweed is an underwater plant with branching, thread-like stems. It has narrow, greenish-brown leaves five to seven centimetres long. It looks very similar to other pondweed species and can be hard to identify correctly.

Action we are taking:


In Canada, Ogden’s Pondweed is found only in southeastern Ontario. It was recorded at Murphys Point Provincial Park and Davis Lock on the Rideau Canal between 1970 and 1990. A historical sighting of the species was recorded in Hastings County in 1873. It has been recommended that additional surveys are needed to determine whether this species exists at any other sites in Ontario. Outside of Canada, Ogden’s Pondweed has been identified in Connecticut, New York, Vermont and Massachusetts.


In Ontario, Ogden’s pondweed is found in clear, slow-moving streams, beaver ponds and lakes. It often grows with other species of narrow-leaved pondweeds, which can make identification of this rare plant even more difficult.


The main threats to Ogden’s Pondweed are habitat destruction and competition from invasive aquatic plants such as Eurasian Water-milfoil. Low population numbers make this species more susceptible to extinction. There is still much to learn about the biology of this rare plant, its habitat needs and threats.


Ogden’s Pondweed and its habitat are protected under Ontario’s Endangered Species Act.

What You Can Do to Help Ogden’s Pondweed

  • The Ministry of Natural Resources tracks species at risk such as Ogden’s Pondweed. You can use a handy online form to report your sightings to the Natural Heritage Information Centre. Photographs with specific locations or mapping coordinates are always helpful. nhic.mnr.gov.on.ca
  • Report any illegal activity related to plants and wildlife to 1-877-TIPS-MNR (847-7667).
  • Private land owners have a very important role to play in species at risk recovery. You may be eligible for stewardship programs that support the protection and recovery of species at risk and their habitats.
  • Volunteer with your local nature club or provincial park to participate in surveys or stewardship work focused on species at risk.
  • Invasive species seriously threaten many of Ontario’s species at risk. To learn what you can do to help reduce the threat of invasive species, visit: ontario.ca/invasivespecies ; www.invadingspecies.com ; www.ontarioinvasiveplants.ca ; and, www.invasivespecies.gc.ca .
  • Soil erosion and runoff introduces pollutants such as fertilizers and pesticides to watercourses in Ontario. There are many things that you can do to help reduce these effects and you might even be eligible for funding assistance. For more information on these and other programs, contact the Ontario Soil and Crop Improvement Association or visit www.ontariosoilcrop.org.

Did you know?

Ogden’s Pondweed was named after pondweed specialist Dr. Eugene Ogden.

Did you know?

Pondweeds provide habitat for aquatic invertebrates (a very important group of creatures in the aquatic food chain), food for mammals and waterfowl, and hiding places for amphibians and fish.

Did you know?

Unlike many other plants that reproduce primarily by seeds, Ogden’s Pondweed reproduces mainly by producing special winter buds called “turions.” These buds grow at the ends of stems and fall to the lake bottom, where they spend the winter and start growing new plants in the spring.

The Endangered Species Act

Contact your local ministry office

Often the best source of local information on species at risk is your nearest ministry office. Call with your questions or concerns.