BC Conservation Data Centre: Conservation Status Report
Packera subnuda var. moresbiensis
Haida Gwaii butterweed
| Scientific Name: | Packera subnuda var. moresbiensis |
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| Scientific Name Synonyms: |
Senecio moresbiensis
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| English Name: | Haida Gwaii butterweed |
| Provincial Status Summary | |
| Status: | S4S5 |
| Date Status Assigned: | March 01, 2020 |
| Date Last Reviewed: | March 01, 2020 |
| Reasons: | There are about 43 populations of Queen Charlotte butterweed reported in BC. This subspecies is widespread on Haida Gwaii and has also been found on extreme northern Vancouver Island and the Central Coast. The long-term presence of browsing deer has resulted in a general decrease in vegetation cover and species richness on Haida Gwaii, but the severity of impacts on reproduction and mortality of Queen Charlotte butterweed is unknown. There is insufficient information available to determine short-term or long-term population trends. |
| Range | |
| Range Extent: | F = 20,000-200,000 square km |
| Range Extent Comments: | This subspecies is endemic to BC and southeast Alaska. The range extent in BC is 27,496 square kilometres, from Haida Gwaii and northern Vancouver Island to the Central Coast on Dewdney Island/Glide Islands and Mount Buxton on Calvert Island. |
| Area of Occupancy (km2): | FG = 126-2,500 |
| Area of Occupancy Comments: | The estimated area of occupancy is at least 100 square kilometres, using a 2km x 2km grid. |
| Occurrences & Population | |
| Number of Occurrences: | C = 21 - 80 |
| Comments: | There are 46 reported populations for this taxon in BC and 32 are located on Haida Gwaii. Populations have also been reported from the central coast at Dewdney Island/Glide Islands and on Mount Buxton on Calvert Island. On northern Vancouver Island, populations were found at Port Hardy, Port McNeill and on the Brooks Peninsula. |
| Number of Occurrences with Good Viability / Ecological Integrity: | CD = 4 - 40 |
| Comments: | The condition of all populations has not been assessed but plants were abundant in many sites and are likely to persist if current conditions prevail. |
| Number of Occurrences Appropriately Protected & Managed: | B = 1 - 3 |
| Comments: | Two populations occur in Ecological Reserves (Dewdney and Glide Islands, Vladamir Krajina) and at least 4 are found in National Parks (Gwaii Haanas). |
| Population Size: | E = 2,500 - 10,000 individuals |
| Comments: | Information on population size was not available for half of the reported occurrences, but the BC population is expected to consist of between 2,600 and 3,200 plants. |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | Moderate, non-imminent threat |
| Comments: | [CD] On Haida Gwaii, the long-term presence of black-tailed deer has had a strong effect on vegetation cover and plant species richness, both of which decreased with increasing length of browsing history. The effect was greatest in the forest edge and among shrub and herb species (Stockton et al. 2005), but the severity of impacts on reproduction and mortality of Queen Charlotte butterweed is unknown. The population of Queen Charlotte butterweed at Port McNeill occurs in wetlands on federal land adjacent to the airport. Maintenance of wetland vegetation by mowing or herbicide application could have a negative impact on populations of Queen Charlotte butterweed, so these activities were discouraged in the environmental site assessment (T. Innis, pers. comm. 2009). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | U = Unknown |
| Comments: | There is insufficient information available to determine short-term trends. |
| Long-Term Trend: | U = Unknown |
| Comments: | There is insufficient information available to determine long-term trends. |
| Other Factors | |
| Intrinsic Vulnerability: | B=Moderately vulnerable |
| Comments: | The fruit is an achene with a small pappus of white bristles,which may be transported by animals or wind. Little is known about the ability of Queen Charlotte butterweed's ability to disperse, but the limited distribution indicates that there may be some barriers to dispersal. |
| Environmental Specificity: | C=Moderate. Generalist or community with some key requirements scarce. |
| Comments: | Habitats include open grass/sedge meadows, mossy slopes, bogs and alpine slopes. According to herbarium records and observations, the plant is often associated with a calcareous substrate (USDA, 2009). |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | Little is known about the plant's life history or demography and further surveys are needed to learn more about its abundance, distribution and population trends. Knowledge of the impact of browsing deer on plants at-risk in heath, rocky slope and other mountain habitats of Gwaii Haanas would allow a more accurate assessment of conservation status. |
| Inventory Needs: | Haida Gwaii has been fairly well-surveyed for this taxon, but other areas on the central coast and Vancouver Island may reveal more sites. |
| Stewardship | |
| Protection: | |
| Management: | |
| Version | |
| Author: | Donovan, M. |
| Date: | May 25, 2010 |
| References | |
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Douglas, G.W. 1996. Endemic Vascular Plants of British Columbia and Immediately Adjacent Regions. Can. Field-Nat. 110(3):387-391.
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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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Stockton, S. A., S. Allombert, A. J. Gaston, and J.L. Martin. 2005. Effects of high deer density on the native flora of coastal temperate rain forests: A natural experiment. Biological Conservation 126:118128
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USDA Forest Service. 2009. Forest Service Alaska Region Sensitive Species List. Assessment and Proposed Revisions to the 2002 List. 47 pp.
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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. 2010. Conservation Status Report: Packera subnuda var. moresbiensis. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 5, 2026).