Scientific Name: Symphyotrichum praealtum
Other/Previous Names: Willow Aster,Aster praealtus
Taxonomy Group: Vascular Plants
COSEWIC Range: Ontario
COSEWIC Assessment Date and Status Change: May 2003
COSEWIC Status: Threatened
COSEWIC Status Criteria: Met criteria for Endangered, B1ab(i,iii)+2ab(i,iii), but designated Threatened due to protection within several Windsor Ojibway Prairie Complex sites and adaptability as evidenced in its ability to colonize open disturbed sites within its main area of occurrence around Windsor and therefore not at imminent risk of extirpation.
COSEWIC Reason for Designation: This is a geographically highly restricted species that has undergone range contraction and occurs mainly in fragmented remnant prairie habitats. There are few occurrences and on-going risks from further habitat and population losses due to presence primarily in urbanized centres.
COSEWIC History of Status Designation: Designated Special Concern in April 1999. Status re-examined and designated Threatened in May 2003.
SARA Status: Schedule 1, Threatened
Date of Listing (yyyy-mm-dd): 2005-01-12
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.
Image of Willowleaf Aster
There are two varieties of the Willowleaf Aster. The range of the variety praealtum extends into Canada, while the eastern variety angustior is limited to the eastern United States.
The Willowleaf Aster is a fall-flowering, upright perennial that grows from a rhizome (spreading underground stem). The plant can be up to 1.5 m tall, and has a relatively smooth, waxy stem with many leafy flower clusters. The flower heads have 20 to 35 outer florets with pale blue to violet rays; the 20 to 30 central florets have a yellow centre, and the rays become purple with age. The leaves on the upper portion of the stem are narrow and linear, with a few small teeth along the margins; the lowermost leaves have usually fallen off by the time the plant is in flower. The seeds are contained individually within fruiting bodies called achene. When mature, the dry achene fall off the parent plant, and are likely dispersed by the wind.
Distribution and Population
The Willowleaf Aster is common in the Midwestern United States, and reaches the northeastern extent of its range in southwestern Ontario. It is highly localised in Canada, and occurs mainly in two concentrated areas around Windsor and on Walpole Island. There are 13 localities known for the Willowleaf Aster; at least one of these, and perhaps as many as five, have become extirpated. No population trend information is available.
The Willowleaf Aster is found in prairies, meadows, and areas of dense shrubs or small trees throughout its range. In southwestern Ontario, it grows most often in oak savannahs, but is also found in disturbed areas such as roadsides, along railways, and in abandoned fields.
It is difficult for scientists to determine the number of genetic individuals of Willowleaf Aster at a site because the species grows from rhizomes, and forms potentially large, overlapping clones. This aster will also reproduce by setting seed if there are enough genetically different species in the population. Pollen is transferred between individuals by insects - primarily bees, flies, and butterflies.
Many of the known populations occur within the city of Windsor, or on nearby Walpole Island. These areas have been heavily disturbed by industrial activities, house construction, and agricultural practices, and there is potential for further development. Sites observed in 1982 on Walpole Island have been eliminated by house construction. It is also likely that changing drainage patterns at some sites are having a critical impact.
The Willowleaf 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 Windsor, a number of populations are protected where they occur within the Ojibway Nature Centre, the Ojibway Prairie Nature Reserves, and the Tall-grass Heritage Park.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Willowleaf Aster (Symphyotrichum praealtum) 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.)
- Permits and Related Agreements (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
Response Statements - Willowleaf Aster (2004-04-21)A response statement is a communications document that identifies how the Minister of the Environment intends to respond to the assessment of a wildlife species by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). The document provides a start to the listing and recovery process for those species identified as being at risk, and provides timelines for action to the extent possible.