Scientific Name: Centaurium muehlenbergii
Taxonomy Group: Vascular Plants
COSEWIC Range: British Columbia
COSEWIC Assessment Date and Status Change: April 2008
COSEWIC Status: Endangered
COSEWIC Status Criteria: B1ab(iii)+2ab(iii)
COSEWIC Reason for Designation: This small annual plant occurs in only three small areas of mainly wet habitat in southwestern British Columbia. Its total Canadian population consists of fewer than 1000 plants. These are highly disjunct from the main range of the species that extends from Oregon to California and Nevada. The species is at continued risk from such factors as the spread of invasive plants and human activities including trampling in areas used for recreational activities.
COSEWIC History of Status Designation: Designated Endangered in April 2008.
SARA Status: Schedule 1, Endangered
Date of Listing (yyyy-mm-dd): 2010-02-23
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.
Muhlenberg’s Centaury is a small annual herb. It typically grows to 4 to 8 cm in Canada. The leaves are arranged on the stem in pairs opposite each other. The small flowers are pink or white. The fruit is a thin capsule containing numerous small brown seeds 0.5 mm long.
Distribution and Population
The range of Muhlenberg’s Centaury extends from southwestern British Columbia south to Oregon, Idaho, Nevada and California. Previously present in southern Washington, it is now reported as extirpated from that state in spite of the fact that it was collected from the San Juan Islands in 1992. Only three extant populations are known in Canada, all of them on or near southeastern Vancouver Island: one in Oak Bay (metropolitan Victoria); a second on one of the Chatham Islands opposite Victoria (Gulf Islands); and the third, discovered in 2003, near Nanaimo. This recent discovery is probably not a new population but an existing one that had previously been missed due to the extremely small number of plants. In Canada, the total population size of Muhlenberg’s Centaury is currently estimated to be between 500 and 1000 plants. The majority of these are located at a single site (Oak Bay). There is no evidence of population declines in the last 10 years, and populations appear to be more or less stable.
In Canada, Muhlenberg’s Centaury is limited to a small area on the southeastern coast of Vancouver Island. This area is strongly influenced by the rain shadow cast by the Vancouver Island Ranges and the Olympic Mountains, and it has a sub-Mediterranean climate characterized by warm, dry summers and mild, wet winters. Muhlenberg’s Centaury is found in various types of moist, open habitats, ranging from vernal pools (seasonally flooded meadows) and seeps to the margins of a coastal saltmarsh. This small annual appears to prefer sites that are wet in the spring but very dry for a large part of the summer. Increasing urbanization round Victoria, combined with the draining of wetlands for agricultural uses and development, has altered the ecology of the region to such an extent that the area suitable for this species has been significantly reduced from historical levels.
There is little information available on the biology of Muhlenberg’s Centaury. The pollination system is unknown, although it is known that other species in the genus can be fertilized by their own pollen and by pollen from flowers that are not closely related. This annual of moist habitats flowers in summer, from June to August, and produces numerous small seeds that remain dormant through the winter and germinate the following year. Some seeds probably remain dormant for longer than a year, forming a persistent seed bank, which would enable the species to recover after periods of unfavourable environmental conditions. Finally, Muhlenberg’s Centaury appears to be a poor competitor and may be susceptible to competition from invasive species, especially introduced grasses.
In British Columbia, the main threat to Muhlenberg’s Centaury is habitat loss due to urbanization. Southeastern Vancouver Island, to which the Canadian populations are restricted, is currently experiencing one of the most rapid rates of urban expansion in North America. Aside from habitat loss, the species is at continued risk from such factors as the spread of invasive plants and human activities, including trampling by people, bicycles and dogs as well as all-terrain vehicle traffic in areas used for recreational activities. Finally, disturbance of the soil by Canada geese could be having negative impacts on Muhlenberg’s Centaury. Canada goose populations have been undergoing exponential growth on southeastern Vancouver Island and adjacent islands since the 1960s. As they graze on vegetation these birds churn up large areas of the soil with their beaks, and this behaviour may be having negative impacts on the growth of Muhlenberg’s Centaury.
The Muhlenberg's Centaury 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.
In British Columbia, Muhlenberg’s Centaury is not protected under any provincial statute. One of the populations is located in a municipal park, which provides some measure of protection.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Muhlenberg’s Centaury (Centaurium muehlenbergii) in Canada
Status Final posting on SAR registry
Garry Oak Ecosystems Recovery Team
Conan Webb - Chair/Contact - Parks Canada
Phone: 250-478-5153 Send Email
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.
7 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.)
COSEWIC Status Reports
Response Statement - Muhlenberg's Centaury (2008-11-26)This small annual plant occurs in only three small areas of mainly wet habitat in southwestern British Columbia. Its total Canadian population consists of fewer than 1000 plants. These are highly disjunct from the main range of the species that extends from Oregon to California and Nevada. The species is at continued risk from such factors as the spread of invasive plants and human activities including trampling in areas used for recreational activities.
COSEWIC Annual Reports
COSEWIC Annual Report - 2007 - 2008 (2008-08-28)2008 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.