Species At Risk

Pale-bellied Frost Lichen

(Physconia subpallida)


Pale-bellied Frost Lichen
Pale-bellied Frost Lichen occurrences map


Pale-bellied Frost Lichen was named for its pale, sometimes bright white crust-like growth that resembles a dusting of frost on a tree trunk. It is usually found in wooded areas where its light colour can be eye catching against the darker surfaces on which it grows (e.g., trees, boulders). The undersurface of Pale-bellied Frost Lichen is light in colour, in comparison to the undersurfaces of its closest relatives which can be much darker, even black.

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Pale-bellied Frost Lichen only occurs in eastern North America. In Canada, it is limited to southern Ontario where it is currently only known from three locations in Frontenac, Lanark and Renfrew counties. Historical specimens were collected from four additional sites in southern Ontario, although Pale-bellied Frost Lichen has not been observed at these historical sites for over 100 years.


Throughout its range, Pale-bellied Frost Lichen grows on the bark of hardwood trees such as White Ash, Black Walnut, and American Elm. It can also be found growing on fence posts and boulders. In Ontario, Pale-bellied Frost Lichen grows on Hop Hornbeam (also known as Ironwood) trunks at a height of 0.5 to 2 metres in wooded areas.


Pale-bellied Frost Lichen appears to be sensitive to air pollution, particularly high levels of sulphur dioxide. This lichen may be capable of expanding its distribution if air quality continues to improve. In addition to air pollution, land-use practices resulting in an overall loss of suitable forested habitat may have contributed to declines across Ontario. The limited distribution of Pale-bellied Frost Lichen also makes it vulnerable to disturbance events such as fire and ice storms.


Pale-bellied Frost Lichen and its habitat are protected under Ontario’s Endangered Species Act.

What You Can Do to Help the Pale-bellied Frost Lichen

  • The Ministry of Natural Resources tracks species at risk such as the Pale-bellied Frost Lichen. 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.
  • As with many other rare plants and animals, Pale-bellied Frost Lichen is at risk due to the loss of forested areas. You can help by protecting any forests and surrounding natural vegetation on your property.

Did you know?

Fewer than 100 individuals are known from the three locations in Ontario.

Did you know?

Pale-bellied Frost Lichen can reproduce sexually and asexually.

Did you know?

Pale-bellied Frost Lichen is sensitive to air pollution and could be useful as an indicator of air quality.

Did you know?

Pale-bellied Frost Lichen doesn’t use roots to access nutrients from the soil. Instead, it grows on the surface of other plants (e.g., trees) or structures (e.g, rocks, fence posts) and derives nutrients from the air and rain.

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.