Western Prairie Fringed Orchid
Scientific Name: Platanthera praeclara
Other/Previous Names: Western Prairie Fringed-orchid
Taxonomy Group: Vascular Plants
Last COSEWIC Assessment: November 2016
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered
Image of Western Prairie Fringed Orchid
The Western Prairie Fringed-orchid is an erect perennial that grows from a tuber that has thick, fleshy roots. The single stem (rarely two or even three) is 40-88 cm high and does not usually have any branches. Along the stem, there are usually 5-7 leaves that are 9-15 cm long and 1.5-3.5 cm wide, the upper ones being reduced in size. The 5-15 cm long flower spike is 5-9 cm wide and consists of 4-33 white or creamy flowers, each with a distinctly fringed lip (lower petal). The seed capsules, each containing many minute seeds, are 2-2.5 cm long and 4-6 mm wide.
Distribution and Population
The Western Prairie Fringed-orchid occurs from southeastern Manitoba south to Kansas. The species has declined significantly throughout its range. More than 90% of the world's known population of the Western Prairie Fringed-orchid occurs in the Red River Valley of North Dakota, Minnesota, and south-central Manitoba. It is likely the orchid was once more widely distributed in southern Manitoba, but that the number of sites where it occurs declined drastically with the loss of tall-grass prairie habitat. Presently, the Canadian population of Western Prairie Fringed-orchids is restricted to a 48 km2 area around the Manitoba townships of Vita and Stuartburn. During a recent survey, there were at least 8,000-9,000 flowering plants in the Canadian population.
The Western Prairie Fringed-orchid grows in highly calcareous (alkaline), stony soils in tall-grass prairie environments. The soil is wet to moderately wet with the water table at a depth of 0-2 m. The plant can be found in open uncultivated areas and along roadsides.
The Western Prairie White Fringed-orchid overwinters as a tuber with roots and a shoot bud. In spring, the bud begins developing and the young shoot emerges in late May. The tuber elongates and increases in size throughout the growing season. A new shoot bud and tuber will form before winter. The old shoot and tuber usually die. The flower spike appears in the third week of June, and the plants bloom in July. The flowering period lasts for up to three weeks, with each flower lasting as long as 10 days. Not all plants flower every year. Non-flowering plants are shorter, have only 1-3 leaves, and fewer, shorter roots. They do not necessarily survive to mature into flowering plants. A large percentage (40-95%) of any population of this orchid may consist of vegetative plants. The number of flowering individuals seems to increase in the year following a growing season with higher than average rainfall. Flowering plants may be either cross- or self-pollinated and about 30% set seeds. Nocturnal sphinx moths with long proboscises are potential pollinators. A large proportion of these moth species are rare in Manitoba. Seed capsules mature by late August-early September, and the seeds are released through slits in the capsule. Seed release continues even after the plant has dried. Capsule production is erratic, resulting from 0 to more than 80% of the flowers. The seeds are minute and are probably dispersed by wind and water. As with other north temperate orchids, seed germination and early development take place underground. There must be a specific fungus present in order for the seedlings to become established. The Western Prairie Fringed-orchid usually reproduces from seeds, but sometimes the parent plant and tuber form two or even three new tubers, each with its own shoot bud. Plants are usually found alone or in small groups. They may not be as long-lived (up to 30 years) as previously believed, and they can exist in a dormant state in the soil for several years.
This orchid is at the northern edge of its range and is limited by climate. It probably has a low reproductive potential and is sensitive to various periodic climatic effects, particularly precipitation and temperature. Habitat loss is the main factor responsible for population declines. Tall-grass prairie has been cultivated to form agricultural fields. Loss of habitat may also be affecting the populations of the orchid’s pollinators, thereby reducing the plants’ ability to reproduce. Overgrazing, intensive hay mowing, drainage of wet areas, competition with introduced species and fire suppression (which allows shrubby species to become established and crowd out, or shade out, the orchids) also negatively influence the orchids. Road maintenance activities, including ditch clearing and spraying with herbicides, has destroyed some plants.
Federal ProtectionThe Western Prairie Fringed Orchid is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
The Western Prairie Fringed-orchid is protected by the Manitoba Endangered Species Act. Under this Act, it is prohibited to harm individuals of this species or its habitat. This plant occurs within the provincial Tall Grass Prairie Preserve.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Western Prairie Fringed-orchid (Platanthera praeclara) in Canada
Status Final posting on SAR registry
Western Prairie Fringed Orchid Recovery Planner
Nicole Firlotte - Chair/Contact - Government of Manitoba
Phone: 204-945-6998 Send Email
Recovery Progress and Activities
Summary of Progress to Date A National Recovery Strategy was developed in 2006. In 1995, the Canadian Nature Federation produced a recovery plan for western prairie fringed orchid. Identification of remaining occurrences of the orchid and protection of sites supporting the orchid and its tall grass prairie habitat were identified as priorities. Since that time, the Manitoba Tall Grass Prairie Preserve has grown to over 2,000 hectares, containing about 80 percent of the Canadian population of western prairie fringed orchid. Summary of Research/Monitoring Activities Annual counts of flowering plants have taken place since 1992 and show dramatic fluctuations from one year to the next. Researchers have identified two moth species that pollinate the western prairie fringed orchid in Manitoba. Populations of these moths are small and the peak activity of the moths does not overlap completely with peak orchid flowering. Additional work is being done to identify factors limiting moth populations (e.g., availability of plants that moth larvae feed upon), which will lead to the development of habitat management measures that could increase the pollinator population. Researchers also are investigating the possibility that alternate nectar sources may attract moths away from orchids and are measuring the impact of light sources in the area that may reduce moth visits of orchids. Recovery action planning will include research and monitoring as a focus to answer a number of questions about the species and factors influencing it. Summary of Recovery Activities Management activities taking place at the Tall Grass Prairie Preserve, such as controlled burning, light to moderate grazing, and occasional mowing, have all been used to reduce woody growth and litter that might otherwise lead to woody species encroachment and crowd out orchids in the Tallgrass Prairie Preserve. Western prairie fringed orchid is listed as threatened in the United States and an American recovery plan has been developed. Information is exchanged regularly between the United States and Canada through the Western Prairie Fringed Orchid Working Group, a group of individuals from various federal, provincial, and state government and non-government agencies that are working with the orchid. A number of plant and animal species at risk are found in and around the Tall Grass Prairie Preserve. A multiple-species approach to recovery action will be implemented to conserve these species and to ensure that the recovery actions required by one or more species are coordinated to the benefit of all.
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.
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- Recovery Strategies (1 record(s) found.)
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