Eastern prairie fringed-orchid COSEWIC assessment and status report: chapter 2

Executive Summary

Eastern Prairie Fringed-orchid
Platanthera leucophaea

Species Information

The Eastern Prairie Fringed-orchid (Platanthera leucophaea) is a tall orchid with alternate lanceolate leaves and a spike of 10-40 creamy-white flowers, each with a prominent fringed petal and a long spur.

Distribution

The species once occurred widely in the northeastern United States, particularly in the southern Great Lakes region and extended northward into southern Ontario.

Habitat

It is a species primarily of mesic prairies, fens and old fields.

Biology

This orchid produces numerous tiny seeds, up to 10,000 per capsule. Seeds must first form an association with a soil fungus that forms mycorrhizae before they can germinate and develop into seedlings. Plants become reproductively mature in approximately 3 to 7 years. A new bud is produced on a fusiform underground tuber in late summer or early fall; from this a stem will grow the following year. Growth begins early in the year and plants usually achieve full size by June. The flowering period in southwestern Ontario extends from about 25 June to 20 July, but this depends on the weather. Capsules ripen in late August and early September.

Plants are adapted to withstand periodic drought and may exist in subterranean, dormant or mycotrophic state (relying on root fungi for nourishment) for one or more years. Following periods of apparent absence lasting several years, the orchid is known to produce dramatic, mass flowerings.

Population Sizes and Trends

With increased search effort since the original report was prepared in 1984, there are now a total of 34 known records for this species with only about 20 populations currently extant (14 extirpated, 13 newly located populations). Most populations are small with the current number of flowering plants documented totalling just over 1000. The population at site 31, once numbering between 1000-1500, is currently nearly extirpated with only a few plants counted in 2000. Not all populations have been surveyed recently for changes in size. Some of the formerly larger populations have declined significantly with those at sites 2 and 3 having decreased in size by 60-80% over the last 20 years.

Limiting Factors and Threats

Habitat has been severely reduced with notable losses over the past decade. Other actual and potential limiting factors include loss of habitat for pollinators, successional change, competition with invasive alien species, human impacts on water tables, deer grazing and natural hybridization.

Special Significance of the Species

This species of orchid is one of the most spectacular and popular in North America. It has a very high profile in the United States due to its listing as a federally threatened species. No Aboriginal uses for this plant have been found in the literature but several other species in the genus are known to have been used for medicinal purposes.

Existing Protection or Other Status Designations

The orchid is recognized as globally imperilled (G2) and was designated in 1989 as threatened under the United States Endangered Species Act of 1973. It is considered as very rare (S2) in Ontario but the species has not been listed under the provincial Endangered Species Act.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of wild species, subspecies, varieties, and nationally significant populations that are considered to be at risk in Canada. Designations are made on all native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fish, lepidopterans, molluscs, vascular plants, lichens, and mosses.

COSEWIC Membership

COSEWIC comprises representatives from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership), three nonjurisdictional members and the co-chairs of the species specialist groups. The committee meets to consider status reports on candidate species.

Definitions

Species
Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X)
A species that no longer exists.

Extirpated (XT)
A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A species facing imminent extirpation or extinction.

Threatened (T)
A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)Footnote1
A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)Footnote2
A species that has been evaluated and found to be not at risk.

Data Deficient (DD)Footnote3
A species for which there is insufficient scientific information to support status designation.

 

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

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