 |
Vancouver Island Beggarticks (Bidens amplissima) in British Columbia (Asteraceae)
Provincial Status: S3
Bidens amplissima, photo by Brian Klinkenberg |
Return to research home page
Visit the E-Flora BC atlas page for this species.
Under the new BC Conservation Framework (currently under development) that denotes provincial responsibility for protection of species at risk in BC, Bidens amplissima is one of the highest scoring species, if not the highest scoring species, for protection in the province (Fraser pers. comm. October, 2007). Bidens amplissima is a rare Pacific Northwest endemic species that is found globally only in coastal areas in British Columbia and adjacent Washington State. More than 85% of its distribution occurs in British Columbia. It is recognized as a species of global importance because of its small global range (Cannings et al. 2005).
In
BC, Bidens amplissima is found on Vancouver Island as far north as Campbell River, and
in the lower mainland in Vancouver, Richmond,
Surrey, Delta, Coquitlam, Pitt Meadows, Aldergrove. It is also found in the Squamish estuary.
Habitat for this species is the narrow alluvial shoreline margins of rivers and ponds, in bogs and willow wetlands, and in the tidal reaches of the Fraser River in British Columbia. At least one station occurs in an old riverbed. In many sites, it occurs with Bidens cernua and Bidens tripartita, with B. amplissima showing preferences for the edges of ponds and lakes, while cernua is often found in standing water. As a shoreline species, it is ecologically tied to seasonally fluctuating water levels, with standing water in winter and spring, light siltation, and substantial summer draw down. In tidal areas, it is found within the tidal reach, where daily inundation and drying occurs.
This species is usually a robust, many branched plant that can reach heights of 4'. Leaves may be either tri-lobed, unlobed or partially lobed. The relatively few large flower heads support several large yellow ray petals, unlike the very similar Bidens tripartita which is usually rayless. When in seed, flower heads resembles burweed. Achene (seed) shape, achene summit shape, and leaf width/length ratio help separate B. amplissima from B. cernua, another similar and closely related species. Flowerheads on Bidens amplissima are hemispherical and do not nod, while those on B. cernua are globular and are generally nodding. Using these traits, re-examination of herbarium specimens led to the discovery that this species is also found in Washington State.
While there are 30 + known stations for this species in BC, most populations consist of only a few individuals. A handful of populations (6) are more substantial, and are comprised of hundreds of individuals. Population numbers for the species at any site vary from year to year based on climatic factors, including winter precipitation and summer temperatures. The species is tied to high winter water levels, and summer draw down that allows seed germination.
Since the preparation of the COSEWIC status report, some populations of this species have been damaged or lost, and others are threatened by development. These losses and threats may indicate a need to elevate the status of this species to Threatened.
Click here for a herbarium specimen comparison of B. amplissima and B. cernua
 |
 |
 |
| Distribution of Vancouver Island Beggarticks in BC. Source: E-Flora BC | Bidens amplissima on Swishwash Island | Bidens amplissima at Jericho Park. |
Acknowledgements:
Preliminary locality information for Bidens amplissima was provided by the British Columbia Conservation Data Centre (BCCDC). Fred Ganders of the University of British Columbia Herbarium (UBC) arranged for specimen loans of this species from other herbaria in Canada and the US, and provided valuable guidance in determining the parameters of the species and the important key characters. His work on Bidens in North America greatly contributed to our understanding of Bidens amplissima. We are grateful to several others who provided site information, disucssions on the species and taxonomic study, and aided with site visits, including, Frank Lomer, Helen Kennedy, Denis Knopp, Jenifer Penny, Jill Sanigan, Lori Daniels, and Hans Roemer. Dave Fraser provided valuable observations on the species, threats to populations, and current status in BC.
Sources:
Cannings, S., M. Anions, R. Rainer and B. Stein. 2005. Our Home and Native Land: Canadian Species of Global Conservation Concern. NatureServe Canada: Ottawa, Ontario.
Environment Canada. 2006. Species at Risk: Vancouver Island Beggarticks. Web site. Accessed 2006. http://www.speciesatrisk.gc.ca/search/speciesDetails_e.cfm?SpeciesID=688
Ganders, Fred, Rose Klinkenberg and Brian Klinkenberg. 2002. British Columbia loses an endemic species: Bidens amplissima (Asteraceae) also occurs in Washington State. Botanical Electronic News, Number 293, July 12, 2002.
Ganders, Fred, Brian Klinkenberg and Rose Klinkenberg. 2003. Taxonomy in Conservation Biology: Investigating the Enigmatic Vancouver Island Beggarticks. Davidsonia 14 (3): 63-70.
Klinkenberg, Brian. 2004. Atlas page for Bidens amplissima. In: E-Flora BC: Electronic Atlas of the Plants of British Columbia. [www.eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver.
Klinkenberg, Brian and Rose Klinkenberg, 2001. Status report on Vancouver Island Beggarticks (Bidens amplissima) in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa.
Page last updated March 2008.