Species At Risk

Blunt-lobed Woodsia

(Woodsia obtusa)


Blunt-lobed Woodsia
Blunt-lobed Woodsia occurrences map


Blunt-lobed Woodsia is a small to medium-sized fern that gets its name from the blunt, rounded lobes of its leaves, known as fronds. The twice-divided bright green fronds may reach up to 60 centimetres in length and 15 centimetres in width. They usually have eight to 17 pairs of leaflets. The leaf stalk is straw-coloured and brittle.

Action we are taking:


Blunt-lobed Woodsia is a relatively common species in the eastern United States. However, in Canada, there are only eight known populations, four in eastern Ontario and four in western Quebec. In Ontario, Blunt-lobed Woodsia is concentrated at sites along the Frontenac Axis, all within approximately 20 kilometres of each other.


In Canada, Blunt-lobed Woodsia is found growing on steep chalky rock faces or escarpments on the Precambrian shield. In Ontario, this species grows only in south-facing locations where the microclimate is warmer. Due to relatively shallow soil over bedrock, the trees around the ferns are typically small to moderate in size and widely scattered. Associated tree species are deciduous, including Sugar Maples, Oaks, White Ash and Ironwood.


The main limitation for Blunt-lobed Woodsia appears to be availability of suitable habitat. At one site in particular, Common Buckthorn, an invasive and non-native species, is considered a threat. At another Ontario site, garbage dumping poses a potential threat.

Development and site alteration are not primary threats, as most of the sites are located on steep rock faces not suitable for development.


Blunt-lobed Woodsia receives protection under Ontario’s Endangered Species Act and the federal Species at Risk Act.

What You Can Do to Help Blunt-lobed Woodsia

  • The Ministry of Natural Resources tracks species at risk such as Blunt-lobed Woodsia. 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 recovery. If you find Blunt-lobed Woodsia on your property, 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.

Did you know?

Blunt-lobed Woodsia may live as long as several decades.

Did you know?

Because Blunt-lobed Woodsia typically grows on steep, largely inaccessible slopes, there may be other populations that have not yet been discovered. The finding of one new population in Ontario in 2004, and two new populations in Quebec in 2000 and 2004, supports this possibility.

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.