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Platanthera praeclara

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Taxonomy [top]

Kingdom Phylum Class Order Family
PLANTAE TRACHEOPHYTA LILIOPSIDA ORCHIDALES ORCHIDACEAE

Scientific Name: Platanthera praeclara
Species Authority: Sheviak & M.L. Bowles
Common Name(s):
English Western Prairie Fringed Orchid
Taxonomic Notes: Sheviak and Bowles (1986) described Platanthera praeclara by dividing Platanthera leucophaea into two separate morphological species differing significantly in pollination mechanisms and in geographic distribution.  The original name P. leucophaea was retained for the species occupying the upper Mississippi River drainage and the Great Lakes region in an area corresponding to the prairie peninsula.  The species inhabiting the prairies of the Missouri River drainage (west of Mississippi River) - the center of the tallgrass prairie formation - was named P. praeclara.

Assessment Information [top]

Red List Category & Criteria: Endangered A2ac ver 3.1
Year Published: 2008
Date Assessed: 2008-01-01
Assessor(s): Goedeke, T., Sharma, J., Delphey, P. & Marshall Mattson, K.
Reviewer(s): Roberts, D., Trembley, R. & Bowles, M. (IUCN SSC Orchid Red List Authority)
Justification:

Globally, P. praeclara is a rare species and under threat; it is listed here as Endangered based on observed population declines across its range in the past ten years due to habitat loss and degradation. International recognition is warranted due to the:

  • Decline in distribution
  • Vulnerability of habitat to development or agricultural conversion
  • Complexity of reproduction
    • Efficiency/effectiveness of pollinators (Cuthrell 1994, Westwood and Borkowsky 2004).
    • Erratic flowering/persistent vegetative state (Pleasants 1993, 1994; Sieg and King 1995).
    • Dormancy periods (Sather 2004).
    • Low seed set (Westwood and Borkowsky 2004).
    • Fungal associates (Sharma 2002; Sharma et al. 2002; Sharma et al. 2003a, 2003b).
  • Sensitivity to hydrological and climatic changes
    • Sensitivity to drought (Sheviak and Bowles 1986, Sears and Linden 2002, Schwarz 2004, Schwarz and Kiecker 2003, Bly 2004, Pleasants 1994).
    • Sensitivity to flooding/standing water (Alexander 2000, 2001; Sather 2002; Sieg and Wolken 1999).

Geographic Range [top]

Range Description:

P. praeclara was historically distributed throughout the western Central Lowlands and eastern Great Plains within the USA, inclusive of the following states: South Dakota, North Dakota, Oklahoma, Iowa, Kansas, Missouri, Minnesota and Nebraska. Presently, extant populations of P. praeclara are found in 45 counties in six states ranging through nine ecoregion sections. Most recently, the US Fish and Wildlife Service (USFWS) indicates that counties containing extant populations are presently found in the states of Iowa, Kansas, Missouri, Nebraska, North Dakota, and Minnesota, with the latter three states having the bulk of the remaining populations. Largest numbers of flowering individuals occur in Minnesota on land preserves managed by the Minnesota Department of Natural Resources and by The Nature Conservancy.  Other sites of significance occur in North Dakota, where over 90% of known orchids are located within the Sheyenne National Grassland, which is managed by the USDA Forest Service.


In Canada,P. praeclara occurs in one extant metapopulation in the Province of Manitoba, occupying approximately 670 ha. Many of the largest patches of plants are currently located within the Manitoba Tall Grass Prairie Preserve.

Countries:
Native:
Canada (Manitoba); United States (Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population:

Population sizes fluctuate considerably over the years for this taxon.  For example, across 43 sites in Minnesota, total counts declined steadily from 5,133 flowering plants in year 2001 to 1,117 flowering plants in 2006.  Of the five known localities in the state of Kansas, plants were not seen at three sites during 2003 and 2006 (time period for which data are available).  One locality contained two flowering individuals in 2004, but none have been documented since.  At another locality, searches in the last two years have yielded no flowering individuals, there were two or three observed in 2003 and 2004, respectively.  In Missouri, across three known sites, while total count has increased from 21 flowering individuals to 38, no flowering plants were seen recently at one location.  In Nebraska, total counts across all monitored sites at times have declined by up to 60% during the last 6 years.  In Iowa, overall, 90-100% decline has been observed over the past at least 20 years at several localities. While at most localities in North Dakota, declines of up to 80% have been observed over the last seven years, two to three sites have shown increases in the numbers of flowering individuals.


The number of plants occurring in Manitoba is difficult to determine because of dramatic fluctuations in numbers from season to season. A low of 1,818 plants were counted in 1995 and a high of 23,530 were recorded in 2003. Fluctuations in the number of flowering individuals are very common for this species, however, it is the overall decline in the numbers of reproductive individuals at each fragmented location which is of biological concern.  

 

These summaries are based on data supplied by Missouri Department of Conservation, Iowa Department of Natural Resources, Minnesota Department of Natural Resources, North Dakota Natural Heritage Inventory, US Fish and Wildlife Service, and Environment Canada.

Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology:

The ideal habitat for P. praeclara is calcareous prairies and sedge meadows, primarily along swales and in marsh areas (Sieg and King 1995, Schwarz 2005, USFWS 1996). P. praeclara is also found in ditches and along roadsides in unmanaged prairie remnants (Crummy 1993, Environment Canada 2006). The orchids prefer higher, drier slopes of swales and ditches, in full sunlight (Alexander 2000, 2001). However, they require a moist soil and warm climate; they do not readily flower in dry areas or during times of drought (Sears and Linden 2002, Schwarz 2004, Schwarz and Keicker 2003, Wolken et al. 2001). P. praeclara appears to require some sort of prescribed fire or grazing management (Pleasants 1994; Sieg and King 1995; Self 2003, 2004; Self and Anthonisen 2005), although uncertainty remains about the appropriateness of specific techniques and regimes.

 

The reproductive ecology of P. praeclara is very complex:

  • P. praeclara requires pollination by specific pollinators, most notably hawk moths (sphingids) (Cuthrell and Rider 1992, Cuthrell 1994). Hawk moths, however, are not conversely dependant upon the orchids. Thus, pollination success can be greatly influenced by timing of flowering, availability of other flowering species, and range of the pollinator in relation to orchid populations (Pleasants 1993, Pleasants and Moe 1992, Westwood and Borkowsky 2004). Moreover, a decline in pollinator populations, due to habitat loss or application of insecticides for example, could adversely impact the P. praeclara.
  • Has erratic flowering, and plant/seed dormancy periods.
  • Needs suitable symbionts.
  • As populations become smaller and more isolated, reduced genetic vigour and a decline in seedling success are likely to occur (Sharma et al. 2002, Environment Canada 2006).
Systems: Terrestrial

Use and Trade [top]

Use and Trade: P. praeclara displays extremely showy flowers and, therefore, it is subject to illegal collection by plant or orchid enthusiasts or those in the plant trade industry. Evidence of illegal collection has been reported in Canada and the USA(Environment Canada 2006, USFWS 1996). Trade in the species is restricted at the national level in both Canada and the USA.

Threats [top]

Major Threat(s):

The most significant threats to P. praeclara are habitat destruction/loss and habitat degradation/alteration, particularly in the USA. Improper management of the intact habitat is also a significant threat to the species. Large tracts of prairie habitat ideal for the orchids have been lost due to conversion of land for agricultural production, especially row-cropping which results in ploughing (Sharma et al. 2002, Lenz 1996, Fauske and Rider 1996, USFWS 1996). In addition, habitat is increasingly lost under pressure of development as both remnant prairie and grazing lands are converted for housing and commercial uses. Although some habitat conversion has been documented in Canada (Collicutt 1993, Punter in press) in recent years, historical trends are not available.

 

The orchids are also at risk from habitat alteration and degradation, which is induced by anthropogenic factors. Inappropriate land management practices can damage individual plants or create ecological changes that disadvantage entire orchid populations. For example, cattle can damage individual plants by grazing and trampling them (Self and Anthonisen 2005; Alexander 2000, 2001; Fauske and Rider 1996). More problematic are management practices and other alterations to associated ecological systems that disadvantage P. praeclara. For instance, non-application or misapplication of prescribed fire, grazing, or mowing could have a detrimental impact on plant survival, growth, and reproduction (USFWS 1996, Self and Anthonisen 2005, Environment Canada 2006). Similarly, a loss of prairie habitat within the landscape matrix could lead to a decline in pollinators and change local hydrology, thereby altering the surrounding vegetative communities (Sharma et al. 2002, USFWS 1996, Wolken et al. 2001). With more dry conditions, for example, Leafy Spurge (Euphorbia esula) an invasive exotic plant species, commonly invades P. praeclara habitat, often out-competing the orchids (Challey 1992, Crummy 1993, Kirby et al. 2003, Wolken et al. 2001). Other exotic species that are observed in the habitat and could potentially out-compete P. praeclara are St. Johns Wort (Hyperiucum perforatum), Smooth Brome (Bromus inermis), Kentucky Bluegrass (Poa pratensis), Reed Canary Grass (Phalaris arundinacea) and clover species (Trifolium sp.) (Environment Canada 2006).

 

There are other factors that are less well understood, but that may threaten P. praeclara. First, the orchid is subject to grazing by wildlife and insects, from which individual plants can sustain damage (Cuthrell and Rider 1992, Cuthrell 1994, Pleasants 1994, Sieg and O’Brien 1993, Self 2003). While such natural grazing may have been sustainable under historical circumstances (meaning when the species was widely distributed), mounting threats, as well as the orchids complex biology/ecology, makes any reduction in fitness problematic.

 

Second, as the biology and ecology of P. praeclara are increasingly understood, concern increases about the threshold of the species. The life cycle and reproductive biology of this species are very complex. As populations continue to decline, biological traits such as erratic flowering, dormancy periods, the need for suitable symbionts, and the need for particular pollinators may reduce the likelihood of recovering the species over the long-term. Finally, as populations become smaller and more isolated, reduced genetic vigour and a decline in seedling success are likely to occur (Sharma et al. 2002, Environment Canada 2006).

 

Other threats to the orchid include damage or destruction of plants by herbicide used during control campaigns for invasive species, roadway maintenance activities, introduction of new, alien species (primarily grasses on grazing lands), and the collection of plants by hobbyists and commercial plant dealers (Environment Canada 2006, USFWS unpublished). A new, potential threat in Canada is the over-application or improper application of fertilizer, specifically hog manure. Problematic application of hog manure on or near orchid habitat could cause harm to the orchid or affect changes in plant communities thereby disadvantaging the orchid (Environment Canada 2006).

Conservation Actions [top]

Conservation Actions:

USA

P. praeclara is federally listed in the USA as threatened under the Endangered Species Act of 1973. Federally protected since 1989, a recovery plan for the species was published in 1996. The focus of recovery has been on “maintaining the habitat of known populations on native prairie and providing the highest level of protection appropriate for all populations” (USFWS 1996). To accomplish these goals, the USFWS seeks to achieve two recovery criteria:

  1. ensuring that a minimum proportion of plants within several ecological units occur on lands that are protected from being converted to non-grassland; and
  2. that those protected plants are subject to appropriate management (USFWS unpublished).

Because many populations of orchids are found on land in private ownership (USFWS 1996), protection of the orchids has largely been approached and executed on an ad hoc basis by various, interested agencies and organizations in the USA. However, according the USFWS (unpublished) three of nine ecological sections having large, extant populations of P. praeclara are currently protected at some level [The Nature Conservancy levels 4 to 9], or nearly so.  The remaining five ecoregions are still with low or no protection for populations. These lands continue to be vulnerable to conversion for agricultural production or development.

 

In terms of management of adequately protected populations, “the Service has not approved any management plans” or “developed specific management guidelines for the species” (USFWS unpublished). Therefore, criterion number two continues to be difficult to achieve.

 

State level conservation measures:

  • Minnesota: Presently, some 84% of orchid plants are protected at some level in Minnesota, most of which occur on land owned by The Nature Conservancy (Sather 2002, 2004).
  • North Dakota: Over 90% of known orchids in North Dakota are found on the Sheyenne National Grassland, which is managed by the USDA Forest Service. The Nature Conservancy also owns land with orchid populations, as do some private land owners. Orchid populations are monitored in North Dakota; state protection and conservation measures are not reported (Lenz unpublished).
  • Iowa: There are 33 known sites hosting orchid in Iowa, 13 of which are protected through state ownership. Seven sites are protected by some other measure on private lands (Pearson unpublished).
  • Missouri: The three sites are managed by the Missouri Department of Conservation.
  • Nebraska: Of the 116 distinct populations presumed extant in Nebraska, most (about 72%) are privately owned and vulnerable to inappropriate management or outright destruction (USFWS unpublished). Only 20 populations are known to be protected.
  • Kansas: Only one of five extant populations of orchids in Kansas is protected in some way. The species is not protected by Kansas state law (Freeman unpublished).

 

Canada

P. praeclara is listed as endangered under Canada’s federal Species at Risk Act since 2003. It is also listed as endangered by the Province of Manitoba under its Endangered Species Act. The latter law prohibits actions that “destroy, disturb or interfere with the habitat of an endangered species”. While there is a National Recovery Plan for the species, this plan has not been formally adopted on either the federal or provincial level.

 

Manitoba is at the northern fringe of the range for this taxon and, as such, habitat supporting the species in this region is limited. According to Environment Canada (2006), “many of the largest patches of plants are found on [Manitoba Tall Grass Prairie] Preserve land—more than 80% of flowering plants observed in 2005 were found there.” The Preserve protects some 3,000 hectares of tallgrass prairie, including prime orchid habitat in Manitoba (Environment Canada 2006).

 

Although knowledge of the full extent of the orchid’s distribution and occurrence in Manitoba is uncertain, particularly on private lands, known populations on the Preserve are managed and monitored for conservation, as per the National Recovery Plan (Environment Canada 2006).


Citation: Goedeke, T., Sharma, J., Delphey, P. & Marshall Mattson, K. 2008. Platanthera praeclara. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 01 September 2014.
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