Species Profile

American Hart's-tongue Fern

Scientific Name: Asplenium scolopendrium var. americanum
Other/Previous Names: Hart's-tongue Fern ,Asplenium scolopendrium ,Asplenium scolopendrium var. americanum
Taxonomy Group: Vascular Plants
Range: Ontario
Last COSEWIC Assessment: November 2016
Last COSEWIC Designation: Special Concern
SARA Status: Schedule 1, Special Concern

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Quick Links: | Photo | Description | Distribution and Population | Habitat | Biology | Threats | Protection | National Recovery Program | Documents

Image of American Hart's-tongue Fern

American Hart's-tongue Fern Photo 1



The American Hart's-tongue Fern is a perennial evergreen fern that grows from a short and stout rhizome (an underground stem). Its rhizome has cinnamon-colored scales on its surface and has a thickened base. The fronds of the American Hart's-tongue Fern are strap-shaped, 12-42 centimeters long, 2-4.5 centimeters wide and are auriculate (i.e., there is a small projecting lobe or appendage at the base). The basal stalk-like parts of the frond are green, 3-12 centimeters long, and have cinnamon-colored scales. Underneath the blades of the frond are linear-shaped sori, which are clusters of spore producing organs.


Distribution and Population

The American Hart's-tongue Fern occurs only in North America, where it is found at the eastern end of the Upper Peninsula of Michigan, southern Canada and in central New York. There are also disjunct populations of the species in northern Alabama and southcentral Tennessee. In Canada, it occurs in southern Ontario only and is closely associated with the Niagara Escarpment. In Ontario, there are 100 known natural occurrences of the American Hart's-tongue Fern, 72 of which are thought to be extant (plants still exist at these sites). Of these 72 occurrences, 26 were confirmed in 1998-1999. Populations vary in size from a single plant to between 10 000-100 000 plants. Population trend estimates are not available, but a few populations are thought to have declined.



Hart’s-tongue fern is a strict calciphile (needs a basic, i.e., non-acidic, substrate). It is generally found only at sites on or near dolomitic limestone. Plants usually occur in damp crevices and on mossy, rock outcrops. In Ontario, many populations are found on steep, moderately moist slopes that face north to northeast, have calcareous soil derived from limestone bedrock and are under a hardwood canopy cover. Most Ontario sites are along or close to the Niagara Escarpment, or in rocky areas where rivers have cut through the glacial deposits and exposed bedrock composed of limestones and dolomites.



The American Hart's-tongue Fern, like all ferns, undergoes alternation of generation. The plants of one generation, the sporophytes, bear asexual spores which give rise to plants of the next generation, which bear sex organs and are known as gametophytes. Spores can disperse great distances. Sporelings require cool, moist, calcareous environments for development. Bryophytes (mosses, liverworts and hornworts) appear to be needed for sporeling survival. They provide sites for fertilization, germination of the spores and growth of the gametophyte.



The major threats to Hart’s-tongue fern populations in North America are related to human activities. In Ontario, threats include logging, quarrying, development, invasion of exotic plants, and trampling along trails.



Federal Protection

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.



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.

1 record(s) found.

Management Plans

  • Management Plan for the Hart’s-tongue Fern (Asplenium scolopendrium) in Canada (2013)

    Hart’s-tongue Fern is a perennial fern with distinct ‘strap’ or ‘tongue-shaped fronds’. In Canada, this species only occurs in Ontario, where it is generally found along the upper and mid-slope positions of the Niagara Escarpment region. It is listed as Special Concern under Schedule 1 of the Species at Risk Act. The Minister of the Environment is the competent minister under SARA for the management of the Hart’s-tongue Fern and has prepared this management plan, as per section 65 of SARA. It has been prepared in cooperation or consultation with the Government of Ontario. The name of this species changed between the proposed and final versions of this management plan. The species was referred to as ‘American Hart’s-tongue Fern’ in the proposed version, but is now known as ‘Hart’s-tongue Fern’.