Species Profile

Ogden's Pondweed

Scientific Name: Potamogeton ogdenii
Taxonomy Group: Vascular Plants
Range: Ontario
Last COSEWIC Assessment: April 2007
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered

Go to advanced search

Quick Links: | Taxonomy | Description | Habitat | Biology | Threats | Protection | Recovery Initiatives | National Recovery Program | Documents

Image of Ogden's Pondweed


Ogden’s Pondweed was first described in 1983 based on specimens gathered in 1970. This is a new species, Potamogeton ogdenii, which likely developed from a cross between P. hillii and P. zosteriformis.



Ogden’s Pondweed is a submerged aquatic plant. The filiform stem is stiff and profusely branched. The greenish brown leaves are long and narrow, measuring 5 to 7 cm in length. Very occasionally, the plant produces dark green fruits that occur in cylindrical spikes measuring 5 to 11 mm in length. In the absence of flowers and fruit, it is difficult to distinguish this annual from other narrow-leaved species of the Potamogeton genus.


Distribution and Population

Ogden’s Pondweed occurs in southern Ontario, western Connecticut, central New York State, central Vermont, and western Massachusetts. There are 19 populations globally, eight of which are considered historic. In Canada, this species has only been observed in three sites in southeast Ontario, where it was last collected in 1987.   Canadian Ogden’s Pondweed populations have been noted in Hastings County (1873), in Murphy’s Point Provincial Park (1974), and at the Davis Lock on the Rideau Canal (1987). Since these sites could not be confirmed in 2005 and 2006, the species' current abundance is not known. However, the existence of suitable environments in the vicinity of the two most recently documented sites suggests that the species probably still occurs in Canada.   Given the overall scarcity of Ogden’s Pondweed in adjacent states, it is unlikely that American populations could help replenish Ontario populations.



Ogden’s Pondweed grows in clear, slow-moving streams, beaver ponds, and lakes. Both Ontario sites are associated with marble bedrock, which means that the water in these aquatic habitats is hard or alkaline.   Since very few sites have been documented in Ontario, little is known about this species’ general habitat trends. However, the unmistakable disappearance of beaver pond habitats in the Murphy’s Point site in recent years has resulted in a reduction of the available habitat. In addition, the presence of invasive aquatic plants in the vicinity of presumed populations suggests a degradation of the quality of this species’ habitat.



Although Ogden’s Pondweed rarely reproduces, the process generally involves the production of winter buds (named hibernacula) or, even more rarely, the production of seeds. Winter buds and seeds are dispersed by water or aquatic birds. Like other aquatic plants, Ogden’s Pondweed is likely a component of the habitats of aquatic invertebrates, as well as food for mammals and aquatic birds, and shelter for amphibians and fish. Very little is known about this recently discovered species.



Potential threats to Canadian populations of Ogden’s Pondweed include the destruction of its habitat (such as the disappearance of beaver ponds) and competition from invasive aquatic plants like the Eurasian water-milfoil.



Federal Protection

The Ogden's Pondweed is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.


Recovery Initiatives

Status of Recovery Planning

Recovery Strategies :

Name Recovery Strategy for Ogden’s Pondweed (Potamogeton ogdenii) in Canada
Status Final posting on SAR registry



PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

9 record(s) found.

COSEWIC Status Reports

  • COSEWIC Assessment and Status Report on the Ogden’s Pondweed (Potamogeton ogdenii) in Canada (2007)

    Ogden’s pondweed (Potamogeton ogdenii) is a submerged, annual aquatic plant with freely branching, compressed and thread-like, rigid stems. The long narrow leaves are greenish-brown. Potamogeton ogdenii is similar to other narrow-leaved members of the genus, such as P. confervoides, P. zosteriformis, P. hillii, P. foliosus, P. friesii, P. strictifolius, P. obtusifolius, and P. pusillus. Ogden’s pondweed was described in 1983 as a new species.

COSEWIC Assessments

Response Statements

  • Response Statement - Ogden's Pondweed (2007)

    This species is an aquatic plant that is globally at risk with low population numbers and only 11 extant sites known worldwide. In Canada, it is known from only 3 sites in southeastern Ontario where it was last collected in 1987. Recent fieldwork has documented the loss of habitat and probable extirpation of one population but failed to relocate the others – one of these is a historic site in a relatively undisturbed region with no specific locality information. The presence of aquatic invasive plants in areas around presumed extant populations suggests a further decline in overall area and quality of habitat for native pondweeds.  However the species, which is easily confused in the field with other similar narrow-leaved pondweeds, may still be present in Canada in suitable habitats in the vicinity of previously known sites.

Recovery Strategies

  • Recovery Strategy for Ogden’s Pondweed (Potamogeton ogdenii) in Canada (2016)

    The Minister of the Environment and the Minister responsible for Parks Canada Agency are the competent ministers for the recovery of Ogden’s Pondweed and have prepared the federal component of this recovery strategy (Part 1), as per section 37 of SARA. SARA section 44 allows the Minister to adopt all or part of an existing plan for the species if it meets the requirements under SARA for content (sub-sections 41(1) or (2)). The Ontario Ministry of Natural Resources (now the Ontario Ministry of Natural Resources and Forestry) led the development of the attached recovery strategy for Ogden’s Pondweed (Part 2) in cooperation with Environment Canada and the Parks Canada Agency.


COSEWIC Annual Reports

  • COSEWIC Annual Report - 2007 (2007)

    2007 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.

Consultation Documents

  • Consultation on Amending the List of Species under the Species at Risk Act - Terrestrial Species (2008)

    As part of its strategy for protecting wildlife species at risk, the Government of Canada proclaimed the Species at Risk Act (SARA) on June 5, 2003. Attached to the Act is Schedule 1, the list of the species that receive protection under SARA, also called the List of Wildlife Species at Risk. Please submit your comments by March 25, 2008 for species undergoing normal consultations and by March 27, 2009 for species undergoing extended consultations.

Recovery Document Posting Plans

  • Environment and Climate Change Canada's Three-Year Recovery Document Posting Plan (2016)

    Environment and Climate Change Canada’s Three-Year Recovery Document Posting Plan identifies the species for which recovery documents will be posted each fiscal year starting in 2014-2015. Posting this three year plan on the Species at Risk Public Registry is intended to provide transparency to partners, stakeholders, and the public about Environment and Climate Change Canada’s plan to develop and post these proposed recovery strategies and management plans. However, both the number of documents and the particular species that are posted in a given year may change slightly due to a variety of circumstances. Last update March 31, 2017