Cover photo credit: USDA-NRCS PLANTS Database, Britton, N.L., and A. Brown


Special Concern

“Special Concern” means the species lives in the wild in Ontario, is not endangered or threatened, but may become threatened or endangered due to a combination of biological characteristics and identified threats.

Date added to the Species at Risk in Ontario List

The Hill’s Pondweed was already assessed as a species of special concern when the Endangered Species Act took effect in 2008.

What it looks like

Hill’s Pondweed is a submersed aquatic plant with stems up,to one metre long. Its narrowly linear sharp-pointed or bristle-tipped leaves are two to six centimetres long with three to five veins. Flower spikes are dense clusters, up to seven millimetres long, with flowers forming one or two whorls.

Where it lives

Hill’s Pondweed is found in slow-moving streams, ditches, ponds, lakes and wetlands. It grows in clear, cold alkaline waters.

Where it’s been found in Ontario

Hill’s Pondweed grows in northeastern United States and Ontario, ranging from Wisconsin, Michigan and Ontario south to south-central Pennsylvania and western Viriginia, and east to Vermont, Massachusetts and Connecticut. In Ontario, it has been recorded at 26 sites in the Bruce Peninsula, Manitoulin Island, Wellington County and Peel Region. Only about 14 of these are presumed to still support Hill’s Pondweed.

map of hill’s pondweed range

View a larger version of this map (PDF)

What threatens it

The main threats to this plant are water diversion, drainage and pollution.

Action we are taking

Special concern species do not receive species or habitat protection.

What you can do

Report a Sighting

  • The Ministry of Natural Resources and Forestry tracks species at risk. 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.


  • Volunteer with your local nature club or provincial park to participate in surveys or stewardship work focused on species at risk.

Be a good steward

  • Private land owners have a very important role to play in species recovery. You may be eligible for stewardship programs that support the protection and recovery of species at risk and their habitats.

Report illegal activity

  • Report any illegal activity related to plants and wildlife to 1-877-TIPS-MNR (847-7667).

Quick facts

  • Hill’s Pondweed can become abundant in some locations and provide dense cover for amphibians and small fish.
  • This plant flowers in the summer, and its small fruits are eaten by ducks.
  • Hill’s Pondweed seeds float.
  • Hill’s Pondweed was not discovered in Ontario until 1951, but a specimen in the Canadian Museum of Nature was collected in 1901. More historical specimens may be discovered in Canadian collections.