Bent Spike-rush Great Lakes Plains population
Scientific Name: Eleocharis geniculata
Taxonomy Group: Vascular Plants
COSEWIC Range: Ontario
COSEWIC Assessment Date and Status Change: April 2009
COSEWIC Status: Endangered
COSEWIC Status Criteria: B1ab(ii,iii)+2ab(ii,iii)
COSEWIC Reason for Designation: 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.
COSEWIC History of Status Designation: Designated Endangered in April 2009.
SARA Status: Schedule 1, Endangered
Date of Listing (yyyy-mm-dd): 2011-02-04
Please note that this information is provided for general information purposes only. For the most up to date and accurate list of species listed under the Species at Risk Act, please see the Justice Laws Website.
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.
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.
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.
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.
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.
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.
Provincial and Territorial Protection
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
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.
8 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- Orders (2 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
COSEWIC Annual Report - 2009 (2009-08-28)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.