Cover photo credit: Allen Woodliffe


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 American Hart’s Tongue Fern was already assessed as a species of special concern when the Endangered Species Act took effect in 2008. A reassessment in May 2017 confirmed this status.

Read the assessment report PDF.

What it looks like

The American Hart’s Tongue Fern is a perennial evergreen fern with fronds that grow from a short and stout underground stem. Its blades are strap-shaped with a heart-shaped base and pointed tip, about 12 to 40 centimetres long or longer, and 2 to 4.5 centimetres wide.

Where it lives

American Hart’s Tongue Fern grows on calcareous rocks in deep shade on slopes in deciduous forest. Most Ontario occurrences are in maple-beech forest. Established plants can grow in exposed, rocky crevices and on outcrops, but moist, mossy areas seem to be essential for spore germination and early plant development.

Where it’s been found in Ontario

American Hart’s Tongue Ferns are found at sites in New York, Michigan, Tennessee, Alabama, Ontario, Oaxaca, Chiapas and Hispaniola. Ontario has the bulk of populations north of Mexico. In this province, the fern has been reported at more than 100 sites, mostly on the Niagara Escarpment, with about 75 of these believed to still exist.

map of hart’s-tongue fern range

View a larger version of this map (PDF)

What threatens it

Populations of American Hart’s Tongue Fern in Ontario are relatively secure, making the province an important refuge for the plant in North America.

In Ontario, threats to the species include logging, quarrying, development, competition from invasive plants, trampling on escarpment trails and collecting for transplanting into gardens.

Action we are taking

Special concern species do not receive species or habitat protection, but may be eligible for grants to help with their protection and recovery.

What you can do

Report a sighting

  • Report a sighting of an endangered animal or plant 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.
  • The Carolinian forests of southern Ontario support an amazing diversity of plants and wildlife, including many species at risk. Carolinian Canada is working to help recover species at risk and their habitats.

Report illegal activity

Quick facts

  • American Hart’s Tongue Fern has very specific habitat requirements, making transplantation and artificial propagation difficult.