Short-rayed Alkali Aster
Scientific Name: Symphyotrichum frondosum
Taxonomy Group: Vascular Plants
COSEWIC Range: British Columbia
COSEWIC Assessment Date and Status Change: April 2006
COSEWIC Status: Endangered
COSEWIC Status Criteria: B1ab(ii,iii,iv,v)+2ab(ii,iii,iv,v)
COSEWIC Reason for Designation: An annual herb of lake shorelines present at only a few remaining sites in restricted habitats. The small populations are subject to disruption from such activities as trampling, beach management, spread of invasive plants and potential development of a major facility at one of the primary sites.
COSEWIC History of Status Designation: Designated Endangered in April 2006.
SARA Status: Schedule 1, Endangered
Date of Listing (yyyy-mm-dd): 2007-12-13
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.
The Short-rayed Alkali Aster is a small annual herb, 5 to 60 cm tall, with many branches. It usually grows flat on the ground but can be erect. Its small flowers are clustered in numerous flower heads, and the heads resemble individual flowers. The heads have small green leaves, called bracts, arranged at the base of the head in a receptacle. The centre of the flower head is composed of small yellow flowers, similar to a daisy, and is surrounded by white or pink threadlike flowers. Plants are generally submersed until late summer, with flowering occurring in August and early September, when the water draws down. A similar species, the rayless alkali aster, can be distinguished from the Short-rayed Alkali Aster by its lack of ray petals dividing the heads.
Distribution and Population
The Short-rayed Alkali Aster is known from Mexico, the United States and Canada. In the United States, it is found in California, Arizona, New Mexico, Nevada, Colorado, Idaho, Montana, Utah, Oregon, Washington and Wyoming. In Canada, it is known only from British Columbia, primarily in the southern Okanagan Valley. The species has been confirmed at four locations: the shores of Osoyoos Lake, the shores of Vaseux Lake, the shores of Skaha Lake and the shores of Max Lake (Penticton). The Osoyoos Lake site supports four sub-populations: one confirmed sub-population, one extirpated sub-population and two unconfirmed sub-populations. An ephemeral disjunct population was reported from Surrey, along the shore of the Fraser River. This site is now extirpated, but this indicates that the species most likely occurs upstream in the Fraser-Thompson drainage basin. Since the abundance of the Short-rayed Alkali Aster fluctuates with annual climatic variation and water levels, observations from single years do not provide a true picture of the species. In addition, the limited data available for each of the four known locations are insufficient to allow trends for this population to be determined.
In Canada, the Short-rayed Alkali Aster has been reported primarily from lakeshore habitats in moist drawdown zones of sandy beaches and the perimeters of alkali lakes and ponds in the southern Okanagan Valley, in British Columbia. In these sites, the water draws down in the late summer and early fall, exposing shallowly sloping moist sites suitable for flowering and seed dispersal. As with other beach sites, heavy beach use and beach maintenance at certain sites have no doubt resulted in habitat degradation.
There is little information on the biology of the Short-rayed Alkali Aster. Based on a few observations, flowering time in British Columbia is from late July to early October. The species appears to be capable of self-fertilization. The adaptability of this aster is unknown; however, three populations occur on heavily used and managed beaches. While it is more abundant in the less trampled areas, it clearly can persist even with some trampling. This shoreline species is also adapted to fluctuating water levels and late summer drawdown. This species can resist high pH and high salinity, but it prefers moist habitats. The dispersal mechanisms of the Short-rayed Alkali Aster are unknown, but dispersal likely occurs by water, waterfowl and wind, in common with other aster species. The observation of a disjunct population in Surrey suggests that long-distance dispersal occurs.
Currently, beach management activities represent a major threat to this species at three sites. These activities, which are carried out in order to maintain the beach for swimming, include roto-tilling, sand sifting, lawn mowing and beach cleaning. Heavy beach use is another major threat to these small populations. Use of the beach habitat by swimmers, boaters and children (digging in the sand, boat launching and storage, trampling and compaction) has a direct impact on this species’ habitat. Invasive plants may pose another serious threat. Finally, like all smaller and fragmented populations of a rare species, populations of the Short-rayed Alkali Aster face the problems inherent in these situations, including the potential for catastrophic loss.
The Short-rayed Alkali Aster 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, the Short-rayed Alkali Aster is not protected under any provincial statute. However, two populations occur, entirely or in part, within provincial parks, where they are protected. Under the British Columbia Parks Act, picking the species is prohibited in a provincial park.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Short-rayed Alkali Aster (Symphyotrichum frondosum) in Canada
Status Final posting on SAR registry
Team for Short-rayed Alkali Aster
Brenda Costanzo - Chair/Contact - Government of BC
Phone: 250-387-9611 Fax: 250-356-9145 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 Statements - Short-rayed Alkali Aster (2006-11-29)An annual herb of lake shorelines present at only a few remaining sites in restricted habitats. The small populations are subject to disruption from such activities as trampling, beach management, spread of invasive plants and potential development of a major facility at one of the primary sites.
COSEWIC Annual Reports
COSEWIC Annual Report - 2006 (2006-08-30)2006 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.