Species Profile

Bent Spike-rush Great Lakes Plains population

Scientific Name: Eleocharis geniculata
Taxonomy Group: Vascular Plants
Range: Ontario
Last COSEWIC Assessment: April 2009
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered


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Quick Links: | Taxonomy | Description | Habitat | Biology | Threats | Protection | Recovery Initiatives | National Recovery Program | Documents

Image of Bent Spike-rush

Taxonomy

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Description

Bent Spike-rush is a small annual, generally 2 to 15 cm tall, but can sometimes reach heights of 20 cm. This tufted plant is composed of numerous slender stalks. Stalks are usually terminated by a single spikelet, approximately 3 to 7 mm long, containing small flowers. This spikelet is composed of hermaphrodite flowers, having both male and female organs, and 1.5 to 2 mm long scales. The plant produces smooth, shiny black dry fruitlets called achenes. Each achene is tipped with a flat and fairly wide tubercle. The black achenes distinguish this species from most other tufted Canadian species of Spike-rush. In Ontario, the species can be confused with Green Spike-rush, with which it sometimes grows. Green Spike-rush, however, has olive-green to brown achenes and a green tubercle. Also, this species is a perennial with underground stems, or stolons, whereas Bent Spike-rush is an annual and lacks stolons.

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Distribution and Population

Bent Spike-rush, which occurs in all tropical areas around the world, is fairly widespread in the southern parts of North America. In Canada, it has been reported from one location in British Columbia, on the east shore of Osoyoos Lake, and from three sites in southwestern Ontario along the northern shore of Lake Erie: Long Point National Wildlife Area, the municipality of Cedar Springs and Rondeau Provincial Park. These occurrences are divided into two distinct populations: the Southern Mountain population, in British Columbia, and the Great Lakes Plains population, in Ontario. Based on the most recent surveys from 2007, the estimated number of mature and fruiting individuals in the Great Lakes Plains population is 300 to 500 at Cedar Springs and 1000 to 2000 at Long Point. The species was discovered in Rondeau Provincial Park in 1934, but was not observed there in 2007 and is most likely extirpated from this site. This site is considered historic. There are few data to assess trends for the Great Lakes Plains population, but the number of individuals at the Cedar Springs site appears to be relatively stable, whereas the population at the Long Point site appears to be declining as available habitat is lost to invasion by Common Reed, an extremely aggressive exotic plant.

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Habitat

Bent Spike-rush is a wetland species found on sand or soil along the edges of ponds and lakes; along canal, river and creek banks; in dunes or other types of depressions; in lagoons and mud flats; and in irrigation ditches and rice fields. In Ontario, this species is found on wet, sandy to muddy soil in open flats or along the edges of ephemeral ponds and wet meadows. These wetlands are flooded throughout much of the year and usually dry during the spring and summer, but sometimes flood again in late summer. Populations at Long Point and Rondeau Provincial Park (historically) are probably somewhat dependent on the fluctuating water levels of Lake Erie. The Cedar Springs site appears to be an abandoned sandpit. The quality of the habitat of the Great Lakes Plains population is declining at all of the known and historical sites because of the very serious invasion of moist open areas by the non-native strain of Common Reed.

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Biology

When conditions are favourable, Bent Spike-rush grows each year from overwintering achenes. Plants grow into early autumn and produce flowers and achenes, then wither and die during the onset of winter. However, not all achenes that are produced germinate the following year. Some remain dormant in the soil, sometimes for many years. Bent Spike-rush depends on this seedbank to maintain the population over the long term, even through years of adverse growing conditions when few or no plants are produced. Annual plants often have wide fluctuations in plant size and numbers and in the numbers of flowers and achenes produced from year to year. In Bent Spike-rush, reproduction is entirely by seed, as there are no means of asexual reproduction in this species. Achenes probably fall close to the plant, but may be moved around the habitat by water flow or animals.

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Threats

In addition to its restriction to a rather specific and geographically limited habitat, Bent Spike-rush is threatened in Canada by several factors, including degradation of this habitat. Rapid invasion into known and potential habitat by Common Reed is a threat to the two known sites of the Great Lakes Plains population, i.e., the Long Point site and the Cedar Springs site. Human-related disturbance is a threat to the Cedar Springs population, as a residential development may be planned for the site. This would likely destroy the Cedar Springs population.

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Protection

Federal Protection

The Bent Spike-rush, Great Lakes Plains population, 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 Great Lakes Plains population of Bent Spike-rush is not protected by any Ontario provincial legislation. One of the sites is located in the Long Point National Wildlife Area, which is federal land protected under the Species at Risk Act. The Rondeau Park site, from which the species is now extirpated, is located in a provincial park.

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.

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Recovery Initiatives

Status of Recovery Planning

Recovery Strategies :

Name Recovery Strategy for the Bent Spike-rush (Eleocharis geniculata) Great Lakes Plains population in Canada
Status Final posting on SAR registry

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Documents

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.

9 record(s) found.

COSEWIC Status Reports

  • COSEWIC Assessment and Status Report on the Bent Spike-rush Eleocharis geniculata in Canada (2009)

    Bent Spike-rush (Eleocharis geniculata) is a small, tufted annual sedge composed of numerous slender stalks (culms). Stalks are usually terminated by a single spikelet composed of bisexual flowers that produce black achenes (small dry fruitlets). Each achene is tipped with a flat and fairly wide tubercle. The black achenes separate this species from most other tufted Canadian species of Eleocharis. Until recently, collections of this species from Osoyoos Lake, British Columbia, had been identified as the Purple Spike-rush (E. atropurpurea), but research has shown this to be in error.

COSEWIC Assessments

  • COSEWIC Assessment - Bent Spike-rush (2009)

    Bent Spike-rush (Eleocharis geniculata) is a small, tufted annual sedge composed of numerous slender stalks (culms). Stalks are usually terminated by a single spikelet composed of bisexual flowers that produce black achenes (small dry fruitlets). Each achene is tipped with a flat and fairly wide tubercle. The black achenes separate this species from most other tufted Canadian species of Eleocharis. Until recently, collections of this species from Osoyoos Lake, British Columbia, had been identified as the Purple Spike-rush (E. atropurpurea), but research has shown this to be in error.

Response Statements

  • Response Statement - Bent Spike-rush, Great Lakes Plains population (2009)

    Only two extant Ontario populations are known for this annual species of the sedge family. The total population consists of possibly fewer than 2500 plants. They occur mainly in sandy wet habitats along ponds and in damp open meadows over an area of only about 2000 square metres. The habitat is declining due to the spread of the invasive, introduced form of Common Reed, an aggressive exotic grass.

Recovery Strategies

  • Recovery Strategy for the Bent Spike-rush (Eleocharis geniculata) Great Lakes Plains population in Canada (2016)

    The Minister of the Environment is the competent minister for the recovery of the Bent Spike-rush and has prepared the federal component of this recovery strategy (Part 1), as per section 37 of SARA. SARA section 44 allows the Minister to adopt all or part of an existing plan for the species if it meets the requirements under SARA for content (sub-sections 41(1) or (2)). The Ontario Ministry of Natural Resources (now the Ontario Ministry of Natural Resources and Forestry) led the development of the attached recovery strategy for the Bent Spike-rush (Part 2) in cooperation with Environment Canada.

Orders

  • Order Acknowledging Receipt of the Assessments Done Pursuant to Subsection 23(1) of the Act (2010)

    Her Excellency the Governor General in Council, on the recommendation of the Minister of the Environment, hereby acknowledges receipt, on the making of this Order, of the Committee on the Status of Endangered Wildlife in Canada’s (COSEWIC) assessments under subsection 23(1) of the Species at Risk Act with respect to the species set out in the annexed schedule.
  • Order Amending Schedule 1 to the Species at Risk Act (2011)

    Her Excellency the Governor General in Council, on the recommendation of the Minister of the Environment, pursuant to section 27 of the Species at Risk Act, hereby makes the annexed Order Amending Schedules 1 to 3 to the Species at Risk Act.

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2009 (2009)

    2009 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.

Consultation Documents

  • Consultation on Amending the List of Species under the Species at Risk Act: Terrestrial Species, December 2009 (2009)

    As part of its strategy for protecting wildlife species at risk, the Government of Canada proclaimed the Species at Risk Act (SARA) on June 5, 2003. Attached to the Act is Schedule 1, the list of the species that receive protection under SARA, also called the List of Wildlife Species at Risk. Please submit your comments by March 1, 2010 for species undergoing normal consultations and by March 1, 2011 for species undergoing extended consultations.

Recovery Document Posting Plans

  • Environment and Climate Change Canada's Three-Year Recovery Document Posting Plan (2016)

    Environment and Climate Change Canada’s Three-Year Recovery Document Posting Plan identifies the species for which recovery documents will be posted each fiscal year starting in 2014-2015. Posting this three year plan on the Species at Risk Public Registry is intended to provide transparency to partners, stakeholders, and the public about Environment and Climate Change Canada’s plan to develop and post these proposed recovery strategies and management plans. However, both the number of documents and the particular species that are posted in a given year may change slightly due to a variety of circumstances. Last update March 17, 2017