BC Conservation Data Centre: Conservation Status Report
Cicuta virosa
European water-hemlock
| Scientific Name: | Cicuta virosa |
|---|---|
| English Name: | European water-hemlock |
| Provincial Status Summary | |
| Status: | S4S5 |
| Date Status Assigned: | April 29, 2015 |
| Date Last Reviewed: | April 30, 2019 |
| Reasons: | Cicuta virosa is fairly widespread and abundant in BC. Its range extent is ca. 500, 000 sq km and Area of occupancy at least 100-500 sq km. It occurs in areas of heavy resource extraction and is likely somewhat threatened by those activities but also occurs in areas where it is not at risk. |
| Range | |
| Range Extent: | G = 200,000-2,500,000 square km |
| Range Extent Comments: | Using GIS tools, Cicuta virosa occurs over 561,992.5 sq km in BC. |
| Area of Occupancy (km2): | FG = 126-2,500 |
| Area of Occupancy Comments: | [E] Using GIS tools, the Index of Area of Occupancy in BC is at least 104 sq km (26 X 4 sq km grid cells). |
| Occurrences & Population | |
| Number of Occurrences: | C = 21 - 80 |
| Comments: | Twenty occurrences are documented in British Columbia as of March, 2012. This species is more abundant than the records indicate (C. Bjork, pers. comm. 2012). |
| Number of Occurrences with Good Viability / Ecological Integrity: | U = Unknown |
| Comments: | Most occurrences lack the sort of documentation that would allow a thorough assessment of viability. |
| Number of Occurrences Appropriately Protected & Managed: | A = None |
| Comments: | Two occurrences are documented from lands with some degree of protection: one from Wells Gray Provincial Park, and one from the Parker Lake Ecological Reserve. |
| Population Size: | U = Unknown |
| Comments: | Occurrences with documentation that allows population size to be assessed suggest that populations are normally small in any given year (fewer than 100 individuals). |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | Slightly threatened |
| Comments: | [D] Some of the known populations occur in the boreal northeast of the province, where the dense network of oil and gas exploration roads, pipelines, powerlines and facilities have created a pervasive grid of disturbance and potential and actual pollution sources. Grazing may also have relatively minor deleterious impacts, given the observed tolerance of C. virosa for moderate eutrophication. Invasions of nonnative species, including Phalaris arundinacea, are a potential concern in some locations. Many other locations, however, are not under threat (C. Bjork, pers. comm. 2013). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | U = Unknown |
| Comments: | Baseline data do(es) not exist that would allow an assessment of short-term trends. |
| Long-Term Trend: | U = Unknown |
| Comments: | Baseline data do(es) not exist that would allow an assessment of long-term trends. |
| Other Factors | |
| Intrinsic Vulnerability: | B=Moderately vulnerable |
| Comments: | The small population sizes may make this species susceptible to stochastic negative outcomes of single or few events. |
| Environmental Specificity: | B=Narrow. Specialist or community with key requirements common. |
| Comments: | Requires wetlands, possibly avoiding those of low pH. Favours in particular older beaver ponds, including those with ruptured beaver dams and a successional process toward marsh-like vegetation. |
| Other Rank Considerations: | The morphology of the Cicuta virosa complex is highly variable. Herbarium specimens show a gradient in leaf pinnation patterns, leaflet size and shape, thickness of stems and umbel pedicels, hemispherical vs. spherical umbel shape. Eurasian specimens tend to have a more delicate appearance with more distinctly ternate leaf divisions. Most North American specimens are less delicate in appearance, and have more distinctly pinnate leaf divisions. Additionally, some British Columbia specimens are much stouter and have broader, shorter leaflets. These stouter plants also may differ in having more spherical umbels and possibly also larger fruits. The observed gradient is between Eurasian and less-stout North American plants. The stout British Columbia form may not intergrade. More study may be needed, both in the field and in the herbarium, though the variability may be excessive for splitting into discrete subtaxa. |
| Information Gaps | |
| Research Needs: | Cicuta virosa in British Columbia remains poorly documented as to population size, phenology, exact localities of occurrences and other basic population data. |
| Inventory Needs: | Much potential habitat occurs in large portions of the province, particularly in the northern half. |
| Stewardship | |
| Protection: | |
| Management: | Occurrences of Cicuta virosa should be allowed to remain natural and unmanaged. |
| Version | |
| Author: | Bjork, C., R. Batten & J.L. Penny |
| Date: | October 18, 2013 |
| References | |
| No references available | |
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. 2013. Conservation Status Report: Cicuta virosa. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 8, 2026).