BC Conservation Data Centre: Conservation Status Report
Bidens amplissima
Vancouver Island beggarticks
| Scientific Name: | Bidens amplissima |
|---|---|
| English Name: | Vancouver Island beggarticks |
| Provincial Status Summary | |
| Status: | S3 |
| Date Status Assigned: | March 07, 2001 |
| Date Last Reviewed: | April 30, 2019 |
| Reasons: | Forty-four verified extant occurrences are known for this species in B.C. and at least 10 have good to excellent viability. A total of ca. 100,000 individual plants have been reported. The estimated extent of occurrence is 54,000 square km and the estimated area of occupancy is 236 square km. Both short and long-term habitat and population trends are unknown, but are believed to be relatively stable. The species appears to be a strong disperser and competitor, is able to tolerate some disturbance (e.g. mowing and trampling) and can colonize some non-native habitats, provided plants are not shaded by a canopy cover. However, at most sites, Bidens amplissima covers only a small area and many habitats have not been secured. One of the largest known populations was at least partially destroyed by highway construction. In addition to development, Bidens amplissima is threatened by disturbance that prevents water saturation and draw-down or results in siltation of the wetland habitats where it occurs (Klinkenberg and Klinkenberg 2001). |
| Range | |
| Range Extent: | F = 20,000-200,000 square km |
| Range Extent Comments: | The range extent calculated for this species, using GIS tools, is 54,295 square kilometres. Except for a single historical location on a research station in Brandon, Manitoba, the entire global range of Bidens amplissima occurs in the Pacific Northwest of North America. In BC, the species is known primarily from Vancouver Island and the Lower Fraser Valley on the adjacent mainland. |
| Area of Occupancy (km2): | FG = 126-2,500 |
| Area of Occupancy Comments: | The estimated area of occupany is 228 square kilometres, using a 2 km x 2 km grid. |
| Occurrences & Population | |
| Number of Occurrences: | C = 21 - 80 |
| Comments: | As of January 2009, there were from 42 to 44 presumed extant occurrences for this species. |
| Number of Occurrences with Good Viability / Ecological Integrity: | C = 4 - 12 |
| Comments: | At least 10 occurrences are estimated to have good viability. |
| Number of Occurrences Appropriately Protected & Managed: | A = None |
| Comments: | At least 17 reported populations occur in parks, sanctuaries, wildlife management areas or ecological reserves (Beaver Lake, Glen Lake, Colquitz Creek, King's Pond, Swan Lake, Rithet's Bog, Somass River Delta, Ladysmith Bog, Comox Estuary, Jericho Park, Richmond Nature Park, Iona Island, Woodward Island, Douglas Island, Minnekada, Pitt Lake and Elgin Park). However, plants are not necessarily effectively protected at these sites, where species specific management may be needed. For instance, activities surrounding the bog at Richmond Nature Park and introduced weeping birch are impacting water availability in the bog and may negatively affect the native species there. Two populations, at the Delta Heronry and the Dow/Delta Slough occur in significant fisheries habitat and are protected by federal legislation from development. The Aldergrove DND site (Aldergrove Department of National Defense Property) has no formal protection, but military staff have indicated that they will attempt to protect the plant (Klinkenberg and Klinkenberg 2001). |
| Population Size: | F = 10,000 - 100,000 individuals |
| Comments: | A total of more than 20,000 plants was estimated, with populations ranging from as few as one plant at a given site to more than 12,000 plants at a location discovered in 2008. However, populations of this annual species are highly variable in numbers of individuals, which fluctuate with annual weather conditions and availability of exposed substrate (S. Hartwell, pers. comm. 2008). |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | Moderate and imminent threat |
| Comments: |
Populations of Bidens amplissima in parks, sanctuaries, wildlife management areas or ecological reserves may be protected from major development, but there is no formal protection for the plants, and public use may impact some populations. In addition, park maintenance activities, particularly mowing, does impact the species in Jericho Park, though it does not appear to prevent its occurrence. Rather, it results in tiny flowering plants (Klinkenberg and Klinkenberg 2001). Bidens amplissima occurs in shoreline marsh and meadow habitats that are frequently highly invaded by aggressive species such as purple loosestrife (Lythrum salicaria) or natural invaders of disturbed wetlands such as reed canary grass (Phalaris arundinacea) or cattails (Typha sp.). However, little difference in abundance of B. amplissima was observed between sites where the loosestrife was eradicated using biological controls, and sites where no biological control was underway, or where the control attempts had been unsuccessful. Klinkenberg and Klinkenberg (2001) believe other factors play a more important role (i.e. siltation, water levels, annual winter precipitation) in the success of B. amplissima at a given site. Invasive species are a particular concern during drought years, when lower water levels allow them to move into a site, and adjacent lawn and turf areas can expand (Klinkenberg and Klinkenberg 2006). The shoreline around the ponds at some sites were well used as resting sites by hundreds of ducks and the disturbance caused by waterfowl activity, as well as the siltation resulting from water level fluctuations, may reduce competition from other wetland plant species (Klinkenberg and Klinkenberg 2001). Tickseed beetle (Coreopsis californica calligrapha) reaches high levels of infestation in some years, causing significant defoliation and the failure of some plants to mature and set seed. This was observed at Rithet's Bog and Somenos Garry Oak Protected area in 2004; both of these populations were considerably reduced in size the following year (S. Hartwell, pers. comm. 2009). Prior to 2008, one of the largest and most significant population of Bidens amplissima was at Hull's Field in Langford. Recently, this population was significantly reduced by the construction of a four-lane highway (J.L. Penny pers. comm.). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | F = Decline of 10-30% |
| Comments: | As populations in B.C. have not been regularly monitored, short term trends are mostly unknown. However, anecdotal observations indicate that numbers of plants fluctuate widely from year to year according to weather conditions (e.g. precipitation) (F. Ganders, pers. comm.; F. Lomer, pers. comm.; S. Hartwell, pers. comm.). Annual summer draw-down appears to be beneficial for this species by reducing competition during peak flowering times. In addition, a reduction of about 4,000 plants was sustained at one location in 2007-08. However, in the same year a new location of ca. 12,500 plants was discovered. Presumably the new location has fluctuated but potentially also occurred in high numbers in the past. Thus, the net decline in the total population is ca. 19 percent. |
| Long-Term Trend: | U = Unknown |
| Comments: | There is insufficient information available to determine long-term trends, but this species is able to tolerate some disturbance such as mowing and trampling and can colonize some non-native habitats provided they are under an open canopy. |
| Other Factors | |
| Intrinsic Vulnerability: | C=Not intrinsically vulnerable |
| Comments: | Population numbers fluctuate with annual variations in precipitation, and abundance of the plant on a yearly basis appears to be directly tied to winter and spring precipitation levels, with low numbers of plants following drier winters. Mature plants produce prolific numbers of seeds that are well-designed for dispersal. Under suitable conditions, large numbers of seeds germinate in the spring. Bidens amplissima appears to tolerate mowing and trampling and can be abundant in these areas. Mowing seems only to shorten the height of the plants, as even tiny individuals that had their tops shorn were able to flower. Genetic research suggests that this is a recently evolved species that shows strong similarity to Bidens cernua and Bidens tripartita (Klinkenberg and Klinkenberg 2001). Hybrid swamping is a natural phenomenon in this species, but may represent an intrinsic vulnerability. |
| Environmental Specificity: | C=Moderate. Generalist or community with some key requirements scarce. |
| Comments: | Bidens amplissima is a shoreline species found within a narrow band of habitat around pond and lake edges, wetland openings and along creeks and riverbanks, in sites with high spring water levels, followed by later summer drying. It has a persistent seed bank, variable germination rates depending on the availability of suitable habitat, and shows a distinct preference for silty alluvial soils. This species also occurs in tidal zones where it is inundated twice a day, and dries out between tides. It can withstand periodic seasonal inundation, annually fluctuating water levels, and both freshwater and brackish conditions. It tends to occur in sites where waterfowl are common, and may be dependent upon the presence of duck populations for dispersal, and for nutrient input (Klinkenberg and Klinkenberg 2001). |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: |
In the past, specimens of Bidens amplissima were mis-identified as B. cernua or B. tripartita. After examining the genetics of the species, Ganders et al. (2000) determined that Bidens amplissima may be the product of past hybridization between B. cernua and B. tripartita and that it is highly unlikely that B. frondosa [as speculated by other authors] is involved in its parentage (Ganders et al., 2000). The ecology of this species indicates that metapopulation dynamics are important in the maintenance and persistence of populations throughout its range. Further studies in population demography would be helpful in determining the role of small populations in maintaining this species in B.C. Research into the extent of threat from predation and herbivory is also recommended (Klinkenberg and Klinkenberg 2006). |
| Inventory Needs: | In 2001, extensive inventory was done for a COSEWIC status report and in 2008, three previously unknown populations were reported. Little information on viability is available for at least 14 occurrences and recovery will depend on the discovery of new populations, so further inventory of suitable habitats and monitoring of existing populations on Vancouver Island and in the Lower Mainland is needed. |
| Stewardship | |
| Protection: | At least 17 reported populations occur in parks, sanctuaries, wildlife management areas or ecological reserves, where they receive some level of protection. The majority of plants in the largest and most significant population for the species was destroyed by highway construction and habitats at the remaining locations are not secure. |
| Management: | In 2007, park crews mistakenly planted oak and dogwood trees over the western end of the population at Jericho Beach Park and in 2008, bald cypress trees were mistakenly planted on the south side of the east pond (R. Klinkenberg, pers. comm.). On both occasions, the planted trees were removed, in response to concerns about the potential habitat modification and population declines resulting from overshading. However, a vegetation management plan that will provide overall site requirements for this species as well as site-by-site details for management actions is needed. These include, but are not limited to, control of successional vegetation and invasive species, chemical management and scheduling of park management activities. Because Bidens amplissima is a wetland species, recovery may be achieved, in part, through wetland protection measures and legislation such as the Fisheries Protection Act (Klinkenberg and Klinkenberg 2006). |
| Version | |
| Author: | Donovan, M. |
| Date: | January 14, 2009 |
| References | |
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Douglas, G.W., D. Meidinger, and J. Penny. 2002. Rare Native Vascular Plants of British Columbia, 2nd ed. B.C. Conserv. Data Centre, Terrestrial Inf. Branch, Victoria. 358pp.
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Ganders, F.R., H. Kennedy, and F. Lomer. 2005. Fraser Valley Flora. Unpubl. manuscript in preparation.
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Ganders, F.R., M. Berbee, and M. Pirseyedi. 2000. AITS base sequence phylogeny in Bidens (Asteraceae): Evidence for the continental relatives of Hawaiian and Marquesan Bidens. Syst. Bot. 25(1):122-133.
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Klinkenberg, B., and R. Klinkenberg. 2001. Status Report on Vancouver Island Beggarticks, Bidens amplissima, in Canada. Unpubl. rep. submitted to the Comm. on the Status of Endangered Wildl. in Can. Ottawa. 25pp.
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Klinkenberg, R. and B. Klinkenberg. 2006a. Management Plan for Vancouver Island Beggarticks (Bidens amplissima Green). Draft Report, September 2006. Prepared for British Columbia Ministr. of Environ., Surrey, B.C.
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Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2009. Conservation Status Report: Bidens amplissima. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 7, 2026).