Species Profile

Scarlet Ammannia

Scientific Name: Ammannia robusta
Taxonomy Group: Vascular Plants
COSEWIC Range: British Columbia, Ontario
COSEWIC Assessment Date and Status Change: May 2001
COSEWIC Status: Endangered
COSEWIC Status Criteria: B1+2cde+3d
COSEWIC Reason for Designation: Annual shoreline aquatic found at fewer than five remaining sites and occupying very small areas of habitat where it exhibits fluctuating population sizes and numbers due to dependence on low water levels and at continued risk from shoreline development, recreational activities and natural or artificial maintenance of high water levels.
COSEWIC History of Status Designation: Designated Endangered in April 1999. Status re-examined and confirmed in May 2001.
SARA Status: Schedule 1, Endangered
Date of Listing (yyyy-mm-dd): 2003-06-05

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.

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Quick Links: | Photo | Description | Distribution and Population | Habitat | Biology | Threats | Protection | Recovery Initiatives | National Recovery Program | Documents

Image of Scarlet Ammannia

Scarlet Ammannia Photo 1



The Scarlet Ammannia is an annual, shoreline aquatic plant that reaches 5-100 cm in height. The glabrous (hairless) stem may be erect or slightly bent over and can be either simple or branched. The 1.5-8 cm long leaves are opposite and oblong to oblong-lanceolate (tapering to a point at both ends) in shape. One to three small, pale lavender flowers with light yellow anthers occur at the base of the leaves. The sessile (stemless) fruits are about 4-6 mm long.


Distribution and Population

The plant occurs in Mexico and throughout central U.S.A. In Canada, it occurs at very few sites restricted to a small area. It is found in the Osoyoos Lake area of southcentral British Columbia, and in Essex County in extreme southwestern Ontario. Four British Columbian sites have been recorded: one at Haynes Point, two in the Osoyoos Indian Reserve, and one at Veronica Lake. Only two of these sites (one population at Veronica Lake and two in the Osoyoos Indian Reserve) were still extant during a 1994/95 survey. Populations at the B.C. sites consisted of 30, 150,000 and 100 plants, respectively. In Ontario, only one of the five known sites had plants (about 50 in number) in 1997.



In British Columbia, the Scarlet Ammannia inhabits moist sandy shorelines, or moist or dry alkaline flats. These sites are submerged in the spring; the plants emerge as the water levels drop in the summer. The Ontario sites are on mudflats, sand beaches, wetland edges, dried pond bottoms, and moist sandy depressions created by dirt bikes.



This plant is generally self-pollinating, although some outcrossing does occur. It is dependent on water level fluctuations for the creation and maintenance of suitable habitat. Because buried seeds survive periods of high water levels and other adverse conditions, visible plants may be absent from a site for several years before conditions again favour growth. However, the species cannot survive sustained high lake levels. Its annual life cycle enables the species to quickly colonize new sites that its seeds have reached.



The Scarlet Ammania is subject to population fluctuations, and the greatest threats to the British Columbia populations are habitat destruction and controlled water level regimes. Habitat destruction has resulted from Provincial Park beach enhancement, shoreline housing and commercial development. The population on Osoyoos private land also depends on lake levels controlled by a dam. In Ontario, high water levels have eliminated or are threatening three populations. Another population is threatened by quarry expansion and encroaching woody vegetation. Housing development and habitat destruction by dirt bikes are threats to another site. A recently discovered population in a bird sanctuary is dependent upon habitat conditions remaining in their current state.



Federal Protection

The Scarlet Ammannia 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

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


Recovery Initiatives

Status of Recovery Planning

Recovery Strategies :

Name Recovery Strategy for the Scarlet Ammannia (Ammannia robusta) 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.

3 record(s) found.

Recovery Strategies

  • Recovery Strategy for the Scarlet Ammannia (Ammannia robusta) in Canada (2015-05-21)

    Under the Accord for the Protection of Species at Risk (1996), the federal, provincial, and territorial governments agreed to work together on legislation, programs, and policies to protect wildlife species at risk throughout Canada. In the spirit of cooperation of the Accord, the Government of British Columbia has given permission to the Government of Canada to adopt the “Recovery Strategy for the scarlet ammannia (Ammannia robusta) in British Columbia and Ontario” under Section 44 of the Species at Risk Act. Environment Canada has included an addition which completes the SARA requirements for this recovery strategy.

Permits and Related Agreements

  • (2006-07-28)

    The activity involves the removal of invasive plants from sites in which three SARA-listed plants occur. Invasive plants, both introduced and native, are the major threat to the habitats and rare plant species at this site. Once key sites are marked, field crews will remove invasive shrubs, trees, and herbaceous plants. Subsequent to this activity, ongoing photographic and plant-response monitoring initiatives will be implemented in order to evaluate the effects of invasive removal activities on the target SAR plants.

Recovery Document Posting Plans

  • Environment and Climate Change Canada's Three-Year Recovery Document Posting Plan (2016-07-06)

    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 December 2, 2021
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