Download Sericocarpus rigidus

BC’s Coast Region: Species & Ecosystems of Conservation Concern
White-top Aster (Sericocarpus rigidus)
Global: G3 Provincial: S2 COSEWIC: SC, BC List: Red
Notes on Sericocarpus rigidus:
A member of the family
Asteraceae (“asters,
sunfklowers”), this is the only
member of the genus
Sericocarpus in Canada. Whitetop aster is also referred to as
“Columbian whitetop aster”
and was formerly known under
the scientific name Aster
curtus. BC’s population
represent approximately 15%
of the global range of this
species.
Juvenile (owlet)
Plant Anatomy
Description
Height 10-30 cm. This perennial herb has upright unbranched, hairless stems which emerge from a network of creeping
rhizomes. The 3 cm long, toothless leaves are arranged alternately along the
stem and taper at both ends with no apparent stalk. The flowers are densely
clustered into 5-20 heads at the top of each stem. Each flower head contains
1-3 long white tufted ray flowers approximately 2 mm in length interspersed
with 9-21 tiny light yellow tubular disk flowers with purplish anthers. The
narrow clasping bracts (modified leaves), below the flower head are white
below with light green tips. The single-seeded fruits possess a tuft of hairlike bristles which assist in dispersal, rather like the fluff on a dandelion.
A number of aster species occur on the Coast Region. The
immature flower heads of the more common California
aster, a co-occurring species have similar features at certain stages of
flowering that could be confused through casual observation with white-top
aster. For the most part however the flowers and leaves of S. rigidus are
quite unique.
Look’s Like?
California Aster
BC’s Coast Region: Species & Ecosystems of Conservation Concern
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Elevations: 10-240 m. In the Pacific Northwest this species is found on the west side of the Cascades in
disjunct populations from the Willamette Valley in Oregon north through the Puget Lowlands of
Washington State and on Southern Vancouver Island. The 22 recorded locations in the Coast Region range from Victoria to
Nanaimo with one population in Port Alberni and another on Hornby Island. Sites with some of the highest concentrations
include Trial Island, Observatory Hill, Woodley Range and Mill Hill.
Distribution
Coast Region
occurrence
range in relation
to associated
forest districts
White-top Aster (Sericocarpus rigidus), known range of population occurrences (red-dotted line) for the Coast Region
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White-top aster prefers
open to lightly-shaded
areas. Plants are often found in edge areas where
openings occur as well as under Garry oak or
Douglas-fir open woodland canopies. This species
often occurs in openings among patches of
snowberry species, along with common camas,
woolly sunflower, yarrow and various species of
grass and sedge. Established plants can tolerate
shading from shrub or tree cover for several years.
Sites can also be dominated by introduced grasses
and often have Scotch broom.
Habitat Preferences
Critical Features
This species is strongly
associated with the open, well drained shallow soil
meadows, bluffs and understories of Garry oak and
coastal Douglas-fir communities. Though somewhat
stress tolerant this species is slow growing,
produces few seeds and does not respond well to
major disturbance.
This species is one of a number of herbaceous plants that occur
in association with Garry oak meadows and upland bluffs.
Seasonal Life Cycle
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Shoots break dormancy from rhizomes November - February, plant fully developed MarchApril, flowering July - September
Maturation of foliage May - September, die-back
to rhizomes occurs September - November
Germination and seedling establishment in the wild appears to be a rare event in BC where seed viability is low and most
seedlings die soon after they germinate. Reproduction is primarily through the underground stems which produce fertile or
sterile shoots at intervals.
Threats
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The preferred ecological associations of this species are geographically limited and subject to urban development and
associated habitat loss
Disturbance, trampling and picking from outdoor recreation activities.
Competition for nutrients and shading from associated vascular plants and subsequently expansion of other more shade
tolerant species.
Fire suppression has led to increased spread and encroachment of competitive plant species (i.e. shrubs) including
native and introduced species.
Grazing from native species (e.g. Columbia Black-tailed deer) and especially introduced species (e.g. Eastern
Cottontail) are contributing to this species decline.
Conservation & Management Objectives
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Apply conservation and management objectives for this species as set out in the “Recovery Strategy for Multi-Species at
Risk in Garry Oak Woodlands in Canada” and the more recent 2009 COSEWIC Assessment and Update Status Report on
the White-top Aster Sericocarpus rigidus in Canada.
Collection activities should be limited and apply practices identified in the Province’s “Voucher Specimen Collection,
Preparation, Identification and Storage Protocol: Plants & Fungi.” Inventory activities should consider approaches and
references identified in E-Flora’s Protocols For Rare Vascular Plant Surveys.
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Specific activities should include:
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Assess actual level and extent of threats to existing populations.
A targeted inventory is needed to determine if undiscovered populations exist elsewhere within the Coast Region.
Conduct outreach to raise awareness of this species and how to identify it to improve distribution knowledge
Monitor existing populations on an ongoing basis to assess viability and reduce potential disturbance from land use
activities.
Where suitable habitat occurs, work with land managers and land owners to ensure development or recreational
activities do not disturb or encroach on sensitive areas.
This species does not produce large quantities of seed. In BC transplants of immature plants have low success. However
transplant of more mature plants and assisted maintenance (watering) appear to increase chances of recolonization
success.
Effective long-term control and reduction in competition from invasive or aggressively spreading vascular plants (e.g.
invasive grasses, Scotch broom, Himalayan blackberry, snowberry species), must form part of strategies to protect and
recover populations. Disturbance to rare plant species and communities must be minimized during control activities.
This species is listed under the Federal Species at Risk Act (SARA) and may be subject to protections and prohibitions
under the BC Wildlife Act. Habitat for this species may also be governed under provincial and federal regulations
including the Fish Protection Act and Federal Fisheries Act as well as Regional and local municipal bylaws.
Content for this Factsheet has been derived from the following sources
B.C. Conservation Data Centre. 2010. [Internet] [Updated May 21 2009] Conservation Status Report: Sericocarpus rigidus. B.C. MoE.
COSEWIC. 2009. COSEWIC Assessment and Update Status Report on the White-top Aster Sericocarpus rigidus in Canada. Committee on the
Status of Endangered Wildlife in Canada. Ottawa. vi + 26 pp.
E-Flora. 2010. [Internet] Electronic Atlas of the Plants of British Columbia
Fairbarns, Matthew. 2010. Aruncus Consulting [Pers. communication].
Garry Oak Ecosystems Recovery Team. 2010. Species at Risk in Garry Oak and Associated Ecosystems in British Columbia. Sericocarpus
rigidus.
Ministry of Environment, Lands and Parks Resources Inventory Branch. 1999. [Internet] Voucher Specimen Collection, Preparation,
Identification and Storage Protocol: Plants & Fungi. Standards for Components of British Columbia’s Biodiversity No. 4b
Parks Canada Agency. 2006. Recovery Strategy for Multi-Species at Risk in Garry Oak Woodlands in Canada. In Species at Risk Act Recovery
Strategy Series. Ottawa: Parks Canada Agency. 58 pps.
Polster, D. et al. 2006.[Internet] Develop with Care: Environmental Guidelines for Urban and Rural Land Development in British Columbia.
Prepared for the BC Ministry of Environment. Victoria (BC).
Proulx, Gilbert et al. 2003. A Field Guide to Species at Risk in the Coast Forest Region of British Columbia. Published by International
Forest Products and BC Ministry of Environment. Victoria (BC).
USDA /NRCS. 2010. [Internet] The PLANTS Database
University of Washington – College of Forest Resources. 2007. [Internet] Native Plants and their Restoration Specifications White-top aster
(Aster curtus).
Prepared by: Pamela Zevit of Adamah Consultants and Matt Fairbarns Aruncus Consulting for the South Coast Conservation Program (SCCP) in
partnership with: International Forest Products (Interfor), Capacity Forestry (CapFor) and the BC Ministry of Environment (BC MoE), E-Flora and
E-Fauna the Electronic Atlas of the Flora and Fauna of BC, Species at Risk & Local Government: A Primer for BC. Funding for this factsheet was
made possible through the Sustainable Forestry Initiative (SFI): http://www.sfiprogram.org/
Every effort has been made to ensure content accuracy. Comments or corrections should be directed to the South Coast Conservation Program:
[email protected]. Content updated August 2010.
Image Credits: White-top Aster: Matt Fairbarns, White-top Aster inset: Rod Gilbert, California Aster: Rod Gilbert, Habitat: Ocean Flynn (Flickr),
Plant anatomy graphic: Gilbert Proulx. Only images sourced from “creative commons” sources (e.g. Wikipedia, Flickr, U.S. Government) can be
used without permission and for non-commercial purposes only. All other images have been contributed for use by the SCCP and its
partners/funders only.
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