BC Conservation Data Centre: Conservation Status Report
Limnanthes macounii
Macoun's meadow-foam
| Scientific Name: | Limnanthes macounii |
|---|---|
| English Name: | Macoun's meadow-foam |
| Provincial Status Summary | |
| Status: | S3 |
| Date Status Assigned: | April 30, 2025 |
| Date Last Reviewed: | April 30, 2025 |
| Reasons: | Very limited distribution, small area of occupancy, specialized habitat requirements, annual life cycle, and reduction in population size in the past 15 years mainly due to human-caused habitat loss and degradation make Limnanthes macounii vulnerable to extirpation. |
| Range | |
| Range Extent: | D = 1,000-5,000 square km |
| Range Extent Comments: | Limnanthes macounii occurs in a coastal strip that is 200 kilometres long by 20 kilometres wide (in many localities, it is 200 metres wide), but suitable habitat is rare and fragmented within this range (Ceska and Ceska 2003). The northernmost locality is on Hornby Island; the southernmost is in East Sooke Park (Ceska and Ceska 2003). |
| Area of Occupancy (km2): | AC = 1-5 |
| Area of Occupancy Comments: | The subpopulations are mainly small and vary in size from 2 to 200 square metres. The total area of occupancy is less than 2 ha (< 0.02 square kilometres). |
| Occurrences & Population | |
| Number of Occurrences: | C = 21 - 80 |
| Comments: | Limnanthes macounii is known from approximately 31 extant populations and approximately 100 subpopulations in B.C. Subpopulations separated by more than 500 metres were considered distinct occurrences (or populations) by the CDC, over-riding the typical standard of 1 kilometre, since L. macounii has very poor dispersal capability and occurs in small, very discrete habitat units with little possibility of suitable habitat between them (the number of populations in the COSEWIC status report, 34, is larger because the 500 metre separation distance had not yet been applied to the CDC records). The likelihood of finding many new localities is low, particularly in the Victoria area. New localities may be found on infrequently visited or remote Gulf Islands, or on coastlines of Vancouver Island that have not been visited by the Ceskas or other expert botanists (Ceska and Ceska 2003). |
| Number of Occurrences with Good Viability / Ecological Integrity: | C = 4 - 12 |
| Comments: | Eleven populations are estimated to have good viability. Viability was assessed based on a number of factors including, but not restricted to, population size. Changes in subpopulations were documented from 1987 (original observation) and 2003 (last observation) and 13 had increased, 12 were considered stable, 18 had declined and 18 were lost (Ceska and Ceska 2003). Another subpopulation was considered restored (previously considered lost). This total (62) is 40 less than the total number of subpopulations (ca. 100) because 40 subpopulations were not known in 1987 and therefore, there is no trend to report. Eight subpopulations have more than 2000 individuals collectively, and 84 subpopulations have more than 200 individuals collectively. Analyses of population viability is limited by available data, but each of the locations was assessed in terms of population size, including changes in subpopulations, presence of exotic species, and potential for human disturbance. Occurences that had lost subpopulations or the subpopulations were decreasing in size were considered of lower quality than occurrences that had newly discovered subpopulations, keeping in mind total size and allowing for normal fluctuations. |
| Number of Occurrences Appropriately Protected & Managed: | D = 13 - 40 |
| Comments: | One population of Limnanthes macounii occurs in a provincial ecological reserve (Trial Island Ecological Reserve); three populations occur in national parks (two in Fort Rodd Hill National Park and one at the Harling Point Chinese Cemetery Historical Park [private property managed with guidance from Parks Canada]); two populations occur in provincial parks (Ruckle Park on Saltspring Island and Drumbeg Provincial Park on Gabriola Island); three populations occur in regional parks administered by the Capital Regional District (two in East Sooke Park and one in Devonian Park); and four populations occur in municipal parks (Saxe Point, Uplands Park/Cattle Point, and Glencoe Cove) (Ceska and Ceska 2003). Eight populations occur on federal lands other than national parks. Most of these occur on Department of National Defence properties and in areas of light use. An additional three populations occur on Indian Reserves. In total, 24 populations of L. macounii occur in protected areas or federal lands that provide some sort of protection for the species. The 14 populations on federal lands and Indian Reserves would be protected under the Species at Risk Act. However, none of the populations is being managed appropriately for long-term persistence. |
| Population Size: | E = 2,500 - 10,000 individuals |
| Comments: | Ceska and Ceska (2003) reported that the B.C. population of Limnanthes macounii is comprised of approximately 10, 000 mature individuals. This is a conservative estimate that takes into account yearly fluctuations in population size in some of the subpopulations (Ceska and Ceska 2003). |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | Substantial, imminent threat |
| Comments: | Two major threats are currently impacting Limnanthes macounii: residential development and introduced plants. For example, development activities have modified or directly destroyed L. macounii habitat by filling in or draining wet depressions, and by building or paving over top of them. Modification of the hydrology of the sites in which L. macounii grows, such as interruption of seepage, has also caused declines in numbers. Introduced plant species represent a major threat to the persistence of L. macounii (Ceska and Ceska 2003) because they can become dominant components of Limnanthes sites. Non-native shrubs, such as Cytisus scoparium and Ulex europaeus, overshadow L. macounii in wetter areas, while Hedera helix, an introduced vine, out competes L. macounii. This has contributed to the decline and disappearance of two subpopulations (Ceska and Ceska 2003). Basal rosette-forming introduced herbs also are major competition for L. macounii, as are newly introduced species such as Trifolium subterraneum and Soliva sessilis, which have very similar ecology and phenology to L. macounii. The most threatening introduced plant species, however, are introduced grasses, especially perennial grasses that form dense swards or large tussocks. They directly compete with L. macounii for light and nutrients, but they also decrease the area of open soil in wet depressions and seepages. These types of grasses, as well as annual grasses, produce biomass that accumulates in the depressions over time, which makes them drier and less suitable for the growth and reproduction of L. macounii. Soil disturbance, such as trampling by humans and digging by Canada geese, is beneficial to L. macounii because it creates the open soil microhabitats the species requires (Ceska and Ceska 2003). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | D = Decline of 50-70% |
| Comments: | Ceska and Ceska (1988, 2003) reported a decline between 1987 and 2003 based on comparisons of population sizes of known occurrences during that period. From the 52 subpopulations known in 1987, 58% had either been lost or had declined when re-sampled in 2003; 27% of these subpopulations had declined and 31% had disappeared. Only 23% had increased. Most of the populations that are presently declining are small (< 50 plants). In the past 15 years, 5 entire populations have been lost (an additional one has recently been restored by removing competing introduced species), 3 have become overgrown with introduced plants, and 3 have been lost due to human activity. Six new populations were found, which represented a substantial increase in range extent (about 100 kilometres further north). The new populations and increase in range extent are not true expansions but are a result of increased search effort in recent years. |
| Long-Term Trend: | D = Decline of 50-70% |
| Comments: | There has been a substantial decline in the number and size of populations and area of occupancy over time, owing mostly to the loss of preferred habitat due to urban and agricultural development and the invasion of introduced plant species. The first collection of Limnanthes macounii occurred in 1875. Although it is difficult to know how common the species was in the late 1800s (or prior to), as early as 1926, human activities were considered responsible for the loss or decline of Limnanthes macounii from historical collection sites (Ceska and Ceska 1988). The Garry oak ecosystem on southern Vancouver Island, with which Limnanthes macounii is associated, has been reduced to 1-5% of its original extent (Fuchs 2001). Most of the Garry oak ecosystem has been lost to agricultural, industrial, and agricultural development following European settlement (Fuchs 2001), and even the remaining small portion has been significantly altered. Introduced species comprise up to 50% of the vascular plant species in remaining Garry oak ecosystems, and they often dominate the herb layer (Ceska and Ceska 2003). The introduction of non-native perennial grasses to the Garry oak ecosystem, which had very few native perennials prior to invasion, has had the biggest negative impact on L. macounii populations. The introduction of non-native shrubs such as Scotch broom has also changed the structure and composition of remaining Garry oak ecosystems. |
| Other Factors | |
| Intrinsic Vulnerability: | A=Highly vulnerable |
| Comments: | Limnanthes macounii is a winter annual that matures quickly and reproduces frequently but has very poor dispersal capability. Extirpated populations are unlikely to re-establish without human intervention. Through its seed bank, L. macounii appears to be capable of revegetating a site that has been overtaken by competitive introduced species, but this has not been well studied. |
| Environmental Specificity: | A=Very narrow. Specialist or community with key requirements scarce. |
| Comments: | Limnanthes macounii is a specialist species that requires seasonally wet (wet or submerged in winter and dry in the summer) pools and depressions or seepage streams/slopes at low elevations in coastal Garry oak ecosystems. Depressions in shallow soil-lining bedrock (a form of vernal pool) and intermittent seepage streams along fractures in bedrock typically have water regimes that are suitable for the growth of L. macounii (Ceska and Ceska 2003). More specifically, L. macounii requires open soil microhabitats within these vernal depressions and seeps. Soil disturbance may be a requirement for the species' survival. Most populations are found in open Garry oak meadows, but several populations are located in depressions and seepy places in open mixed forests of Douglas-fir, Garry oak, arbutus, Rocky Mountain juniper, or lodgepole pine. L. macounii is highly specialized ecologically and is ill-adapted to major changes in water regime and physical habitat features. It is restricted to very rare landscape features in a rare ecosystem type (i.e., Garry oak ecosystems) that is found only on southern Vancouver Island and adjacent islands. Also found at Rocky Point in a fire-break area that is underlaid with clay which is moist in the spring and dries out in the summer. The site is disced twice a year in May and October which leaves furrows running roughly north to south. The water collects in these during the winter/early spring, and creates a 'vernal pool' type haibtat. The area is surrounded by Douglas-fir on the Beecher Bay IR side (southwest), and an open area of non-native grasses and Carex tumulicola on the northeast side in the munitions or restricted area, this area is mowed on a regular basis (B. Costanzo, pers. com.). |
| Other Rank Considerations: | Limnanthes macounii is endemic to B.C. (southern B.C.). It is not known from anywhere else in Canada or the world, which gives it special conservation value. |
| Information Gaps | |
| Research Needs: | Long-term monitoring of Limnanthes macounii populations in terms of population size, area of occupancy, and number of populations is highly recommended. The negative effects of introduced plant species has been observed. Further restoration experiments (removal of introduced species [Ceska and Ceska 2003]) are recommended to determine the best methods for restoring L. macounii on sites where it is being heavily out competed or extirpated. For example, it is important to determine the timing or rotation of the removal treatments and what factors may result in permanent elimination of introduced species from L. macounii sites. Seed bank dynamics of L. macounii are also poorly understood. Information on seed viability and longevity in the soil would be useful for conservation purposes. The level of genetic variation within several populations and subpopulations has been studied, but further genetic studies may help assess population viability. The number of subpopulations and populations, defined by the rate of genetic exchange via seed movement and pollen exchange, is difficult to establish. Seed dispersal between subpopulations is probably very limited. The species is mostly self-pollinated, so it is unclear how much pollen is exchanged. Research into rates of genetic exchange is required to address these issues and define distinct populations. |
| Inventory Needs: | It is unlikely that many new localities will be discovered. Ceska and Ceska (1988, 2003) have intensively searched suitable habitats over the past 30 years. New localities may be discovered on infrequently visited Gulf islands adjacent to Vancouver Island, but there is low priority for inventories of new populations. |
| Stewardship | |
| Protection: | Because Limnanthes macounii occurs in a broad range of ownership categories from private property to provincial ecological reserves, a cohesive legal protection plan that is applicable across all jurisdictions is recommended but will be difficult to implement. The Trial Island subpopulations are legally protected from damage under the Protected Areas of British Columbia Act, but this legislation is not enforced. The Species at Risk Act (SARA) will protect many populations of this species due to the large number that occur on federal lands. Protective covenants and stewardship agreements are required for populations on private lands. One protective covenant was already put in place to protect one population of L. macounii on private property, but the population was later eliminated. |
| Management: | A coordinated management plan is required to monitor populations of Limnanthes macounii across the range of properties on which they occur (private, provincial [parks and ecological reserves], Capital Regional District, municipal, Indian Reserves, and other federal lands). Restoration activities should be designed and planned for sites that are experiencing heavy competition from introduced plant species. Management of L. macounii on private lands should include education of private land owners, incentive packages, stewardship agreements, and protective covenants. |
| Version | |
| Author: | Bartemucci, P. and J.L. Penny |
| Date: | August 07, 2007 |
| References | |
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Ceska, A., and O. Ceska. 1988. Status Report on Macoun's Meadowfoam, Limnanthes macounii, in Canada. Unpubl. rep. submitted to the Comm. on the Status of Endangered Wildl. in Can. Ottawa. 44pp.
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Ceska, A., and O. Ceska. 2003c. Update COSEWIC Status Report on Macoun's Meadowfoam, Limnanthes macounii, in Canada. Unpublished rep. submitted to the Comm. on the Status of Endangered Wildl. in Can. Ottawa. Draft. 32 pages.
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COSEWIC. 2004l. COSEWIC assessment and update status report on the Macoun's meadowfoam Limnanthes macounii in Canada. Comm. on the Status of Endangered Wildl. in Can. Ottawa. vi + 24pp.
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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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Fuchs, Marilyn A. 2001. Towards a Recovery Strategy for Garry Oak and Associated Ecosystems in Canada: Ecological Assessment and Literature Review. Tech. Rep. GBEI/EC-00-030. Environ. Can., Can. Wildl. Serv., Pac. and Yukon Region.
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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. 2007. Conservation Status Report: Limnanthes macounii. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 13, 2026).