Macoun’s Meadowfoam (Limnanthes macounii): COSEWIC assessment and status report 2023

Official title: COSEWIC assessment and status report on the Macoun’s Meadowfoam (Limnanthes macounii) in Canada

Committee on the status of Endangered Wildlife in Canada (COSEWIC)

Special concern

2023

COSEWIC assessment summary

Assessment summary – December 2023

Common name: Macoun’s Meadowfoam

Scientific name: Limnanthes macounii

Status: Special Concern

Reason for designation: This plant is a Canadian endemic that occurs within a narrow coastal fringe of seasonally wet microhabitats where it is at risk from continued competition with a wide range of exotic plants, increasing frequency of extreme weather events, and possible consumption by introduced and locally abundant Canada geese. The known population of this plant has increased considerably since the last assessment due to more search effort. This has resulted in the discovery of new sites, including a managed site, that increases the total population size 50-fold. The status has changed primarily due to a change in the way assessment criteria are now applied; the population is no longer considered to be severely fragmented.

Occurrence: British Columbia

Status history: COSEWIC: Designated Special Concern in April 1988. Status re-examined and designated Threatened in November 2004. Status re-examined and designated Special Concern in December 2023.

COSEWIC executive summary

Macoun’s Meadowfoam

Limnanthes macounii

Wildlife species description and significance

Macoun’s Meadowfoam is a small (2 to 5 cm tall, rarely up to 15 cm) annual plant with pinnately compound leaves. The flowers are bell- to bowl-shaped, with four white petals 4 to 5 mm in length. The fruits are yellow-green to light-brown nutlets.

Macoun’s Meadowfoam is the only member of the genus and one of only two species in the family Limnanthaceae found in Canada. Of the 20 currently recognized global taxa in the family, eight are of conservation concern. Limnanthes species may provide genetic material for breeding programs for Limnanthes crops grown for seed oil or glucosinolates.

Distribution

Macoun’s Meadowfoam is endemic to southeastern Vancouver Island and the adjacent Gulf Islands in British Columbia. It has not been found on mainland British Columbia or in the United States.

Habitat

The species occurs in open areas, including light, open forests, in microsites that are fully saturated or shallowly submerged in the winter and completely dry in the summer and that contain short or sparse vegetation. Most subpopulations are found on coastal shorelines within 200 m of the ocean, where the salt spray and shallow soils (ranging from a few cm to 30 cm deep) limit competing trees and shrubs. The species’ habitat includes vernal pools, intermittent seepages, wet depressions, ends of seepage streams, and depressions and seepages in open forests.

Biology

Macoun’s Meadowfoam is a winter annual, germinating after the fall rains and growing at a time when most other plants are dormant. Plants flower from March to early May, and the nutlets mature by the beginning of June. Germination rates are low, suggesting that the species staggers germination and relies on seed banks in unfavourable years. Nutlet dispersal is presumed to occur by water over short distances. Although bees and flies pollinate other Limnanthes species, it is not known which species pollinate Macoun’s Meadowfoam or if pollinators are required, given that the plants are self-compatible.

Population sizes and trends

Macoun’s Meadowfoam is known from 31 extant subpopulations, a third of which have more than one site. Most plants are found in one large subpopulation, Whirl Bay, in a maintained firebreak, which is estimated to contain over 4 million plants. An additional 13 subpopulations have over 1,000 plants each, while the remainder have fewer than 400 plants apiece. The total population is estimated to be between 4,270,000 and 4,275,000 plants based on the most recent count data. The number of plants found fluctuates each year in association with annual weather variations. Some subpopulations and sites within subpopulations have been destroyed by development.

Threats and limiting factors

Threats to the species associated with climate change include drought, comprising both unseasonably dry periods in early spring, which impact seed set, and dry weather in the fall or winter, which can damage plants and seedlings. More extreme storms may cause the flooding of vernal pools with salt water or increase sea spray at low-elevation sites next to the shoreline. Temperature extremes can delay germination or exacerbate droughts.

Non-native invasive shrubs, including Scotch Broom, Gorse and English Ivy, can degrade habitat by casting shade, altering vegetation structure and fixing nitrogen, which can create favourable conditions for other invasive species. Invasive grasses reduce available moisture, decrease the amount of bare soil available in depressions and seepages and, over time, cause thatch accumulation in the depressions and increase organic soil matter, resulting in competing vegetation growth and drier pools with habitat less suitable for Macoun’s Meadowfoam. Finally, non-native forbs can also compete for light and moisture with Macoun’s Meadowfoam.

Recreational activities, including hiking, picnicking and camping, can spread invasive plants. Although the light trampling associated with recreational activities appears to benefit Macoun’s Meadowfoam by limiting competition from invasive plants, excessive trampling results in compacted soils that produce smaller, less productive Macoun’s Meadowfoam plants. Development on private and publicly owned land has destroyed historical subpopulations either directly through construction or by altering the hydrology required for seepage conditions.

Limiting factors include a lack of the specialized seepage or pool habitat that the species requires, limited dispersal mechanisms and genetic isolation.

Protection, status and ranks

Macoun’s Meadowfoam is listed as Threatened on Schedule 1 of the Species at Risk Act. It is ranked Imperiled (S2?) in British Columbia, Imperiled (N2?) in Canada and Imperiled (G2?) globally.

Eleven occurrences are federally managed, three are on First Nations’ reserve lands, five are provincially managed, eight are in regional parks, and nine occurrences are on private land.

Technical summary

Limnanthes macounii

Macoun’s Meadowfoam

Limnanthe de Macoun

Range of occurrence in Canada (province/territory/ocean): British Columbia

Demographic information

Generation time (usually average age of parents in the population; indicate if another method of estimating generation time indicated in the IUCN guidelines (2011) is being used)

1+ years. No information available on seed bank half-life. Species likely uses staggered germination, relying on seed banks in unfavourable years.

Is there an [observed, inferred, or projected] continuing decline in number of mature individuals?

Yes, inferred due to decline in habitat and loss of two subpopulations since 2003

Estimated percent of continuing decline in total number of mature individuals within [5 years or 2 generations, whichever is longer up to a maximum of 100 years]

Unknown

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over the last [10 years, or 3 generations, whichever is longer up to a maximum of 100 years]

Unknown

[Projected or suspected] percent [reduction or increase] in total number of mature individuals over the next [10 years, or 3 generations, whichever is longer up to a maximum of 100 years].

Unknown

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over any period [10 years, or 3 generations, whichever is longer up to a maximum of 100 years], including both the past and the future.

Unknown

Are the causes of the decline a. clearly reversible and b. understood and c. ceased?

1. yes
2. yes
3. no

Are there extreme fluctuations in number of mature individuals?

No (annual fluctuations mitigated by the seed bank)

Extent and occupancy information

Estimated extent of occurrence (EOO)

4,723 km²

Index of area of occupancy (IAO)

(Always report 2x2 grid value).

100 km²

Is the population “severely fragmented” that is, is >50% of its total area of occupancy in habitat patches that are (a) smaller than would be required to support a viable population, and (b) separated from other habitat patches by a distance larger than the species can be expected to disperse?

1. No, the viability of most of the subpopulations was assessed as fair to good in the recovery strategy
2. Yes

Number of “locations” (use plausible range to reflect uncertainty if appropriate)

36 to 39

Is there an [observed, inferred, or projected] decline in extent of occurrence?

No

Is there an [observed, inferred, or projected] decline in index of area of occupancy?

No

Is there an [observed, inferred, or projected] decline in number of subpopulations?

Yes, two subpopulations are presumed to have been extirpated since the 2003 status report.

Is there an [observed, inferred, or projected] decline in number of “locations”?

Yes, two locations are presumed to have been extirpated since the 2003 report.

Is there an [observed, inferred, or projected] decline in [area, extent and/or quality] of habitat?

Yes, inferred decline in area and quality of habitat

Are there extreme fluctuations in number of subpopulations?

No

Are there extreme fluctuations in number of “locations”?

No

Are there extreme fluctuations in extent of occurrence?

No

Are there extreme fluctuations in index of area of occupancy?

No

Number of mature individuals (in each subpopulation)

Subpopulation Name (Year of most recent count)

N Mature Individuals

Beechy Head (2022)

20

Creyke Point (2022)

305

Becher Bay IR #2, West of Rocky Point (2006)

1,170 to 1,600

Church Point, West of (2010)

1,957

Rocky Point, East (2015)

14,813

Quarantine Cove (2022)

245

Mary Hill, Southeast and Southwest Slopes (2010)

8,624

Mary Hill, Northeast Base (2010)

252

Devonian Regional Park (2022)

45

Saxe Point (2022)

83

Montreul Hill (2003)

> 250

Albert Head (2022)

335

Hornby Island (2022)

1,330

Fort Rodd Hill (2021)

3,500

Yew Point (2020)

~ 1,400

Harling Point (2022)

> 3,000

Trafalgar Park (2022)

422

Trial Islands (2022)

4,797

Gonzales Point (2022)

218

Chatham Islands (2016)

> 200

Uplands Cattle Point (2020)

2,970 to 4,320

Gordon Head (2022)

128

Yellow Point (2022)

18,590 to 20,000

Saltspring Island (2022)

3,186

Gabriola Island, Drumbeg Provincial Park (2018)

150 to 175

Ross Bay (2022)

102

Inskip Island (2003)

> 200

Becher Bay IR #2, North of (2006)

80 to 150

Pedder Bay (2022)

392

Whirl Bay (2012)

~4,200,000

Turkey Head (2021)

1,000 to 2,500

Duntze Head (2010)

43

Total

4,270,167 to 4,274,592

Quantitative analysis

Is the probability of extinction in the wild at least [20% within 20 years or 5 generations whichever is longer up to a maximum of 100 years, or 10% within 100 years]?

Analysis not conducted

Threats (direct, from highest impact to least, as per IUCN threats calculator)

Was a threats calculator completed for this species? Yes (Appendix 1). Threat impact Medium .

1. 11.2 Droughts (High - Low)
2. 8.1 Invasive Non-native/Alien Species/Diseases (Medium - Low)
3. 1.1 Housing and Urban Areas (Low)
4. 1.2 Commercial and Industrial Areas (Low)
5. 6.1 Recreational Activities (Low)
6. 7.3 Other Ecosystem Modifications (Low)
7. 10.2 Earthquakes/Tsunamis (Unknown)
8. 11.3 Temperature Extremes (Unknown)
9. 11.4 Storms and Flooding (Unknown)

What additional limiting factors are relevant?

Macoun’s Meadowfoam is restricted to a highly specific habitat that is naturally rare in the landscape. Nutlet dispersal is limited, which prevents subpopulation expansion and the establishment of new subpopulations. The impacts of genetic isolation (for example, inbreeding depression, genetic drift, decreased adaptability to environmental change, etc.) are unknown.

Rescue effect (immigration from outside Canada)

Status of outside population(s) most likely to provide immigrants to Canada.

Does not occur outside of Canada

Is immigration known or possible?

No

Would immigrants be adapted to survive in Canada?

N/A as the species is endemic to Canada

Is there sufficient habitat for immigrants in Canada?

N/A as the species is endemic to Canada

Are conditions deteriorating in Canada?

Yes

Are conditions for the source (that is, outside) population deteriorating?

N/A

Is the Canadian population considered to be a sink?

N/A as the species is endemic to Canada

Is rescue from outside populations likely?

No

Data sensitive species

Is this a data sensitive species?

No

Status history

COSEWIC: Designated Special Concern in April 1988. Status re-examined, and species designated Threatened in November 2004. Status re-examined, and species designated Special Concern in December 2023.

Status and reasons for designation:

Status: Special Concern

Alpha-numeric codes: Not applicable

Reasons for designation: his plant is a Canadian endemic that occurs within a narrow coastal fringe of seasonally wet microhabitats where it is at risk from continued competition with a wide range of exotic plants, increasing frequency of extreme weather events, and possible consumption by introduced and locally abundant Canada geese. The known population of this plant has increased considerably since the last assessment due to more search effort. This has resulted in the discovery of new sites, including a managed site, that increases the total population size 50-fold. The status has changed primarily due to a change in the way assessment criteria are now applied; the population is no longer considered to be severely fragmented.

Applicability of criteria

Criterion A (decline in total number of mature individuals):

Not applicable. Data are insufficient to determine trends. There has been a large increase in the known Canadian population due to the discovery of the species at a managed site.

Criterion B (small distribution range and decline or fluctuation):

Not applicable. EOO of 4,723 km² and IAO of 100 km² are both below the threshold for Endangered and, although habitat quality is declining, the population is not severely fragmented, occurs at > 10 locations, and does not experience extreme fluctuations.

Criterion C (small and declining number of mature individuals):

Not applicable. Number of mature individuals exceeds the threshold for Threatened.

Criterion D (very small or restricted population):

Not applicable. Number of mature individuals exceeds thresholds for D1. IAO, number of locations and projected threats do not indicate that the population is at risk of imminent extirpation.

Criterion E (quantitative analysis):

Not applicable. Analysis not conducted.

Preface

This report is an update to previous COSEWIC status reports prepared in 1988 and 2004, both of which were written by Adolf and Oluna Ceska. The provincial Macoun’s Meadowfoam Recovery Strategy was written in 2011 (Garry Oak Ecosystems Recovery Team Plants at Risk Recovery Implementation Group 2011) and was incorporated in part in the federal Recovery Strategy in 2013 (Parks Canada Agency 2013). Since the 2004 status report, two new subpopulations (Whirl Bay and Turkey Head) have been discovered and a third subpopulation (Duntze Head), which was not previously included in the British Columbia Conservation Data Centre (BC CDC) database, has been added. Finally, subpopulations are distinguished by a separation distance of 500 m, whereas 1,000 m was used in the previous report. This change was implemented due to the species’ very poor dispersal capability and the small, very discrete habitat units with no suitable habitat between them.

COSEWIC history

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions (2019)

Wildlife species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)

A wildlife species that no longer exists.

Extirpated (XT)

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A wildlife species facing imminent extirpation or extinction.

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed.

Special concern (SC)
(Note: Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.)

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at risk (NAR)
(Note: Formerly described as “Not In Any Category”, or “No Designation Required.”)

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data deficient (DD)
(Note: Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” [insufficient scientific information on which to base a designation] prior to 1994. Definition of the [DD] category revised in 2006.)

A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.

The Canadian Wildlife Service, Environment and Climate Change Canada, provides full administrative and financial support to the COSEWIC Secretariat.

Wildlife species description and significance

Name and classification

Scientific name: Limnanthes macounii Trelease (1887)

Type specimen: John Macoun, Collection # 2877 (CAN 10090418), May 7, 1875; “in ditches at Victoria” Vancouver Island

Synonyms: Floerkea macounii (Trelease) Trelease

Common name: Macoun’s Meadowfoam

Common French name: Limnanthe de Macoun

Family: Limnanthaceae

Allozyme studies showed that Macoun’s Meadowfoam had alleles at three loci found in no other taxa (Kesseli and Jain 1984). However, based on internal transcribed spacer (ITS) analysis, Plotkin (1998 in Tucker 2010) concluded that Macoun’s Meadowfoam should be included in Douglas’ Meadowfoam (L. douglasii). The study by Meyers et al. (2010) on limited genes (one nuclear and two chloroplast) indicates that Macoun’s Meadowfoam may not be a distinct species, but suggests that taxonomic changes are premature pending the sampling of complete chloroplast genomes and nuclear loci.

The native ranges of the two species do not overlap: Douglas’ Meadowfoam is native to Oregon and California (Morin 2021), whereas Macoun’s Meadowfoam is only found in southwestern British Columbia. However, Douglas’ Meadowfoam is a horticultural species that is grown in British Columbia and may be found outside of gardens in disturbed ground (iNaturalist 2023). Macoun’s Meadowfoam is currently maintained as a distinct species in the Flora of North America because of its unique characteristics and disjunct distribution (Tucker 2010).

In 1998, Eva Buxton found large numbers of four-petalled plants initially identified as Macoun’s Meadowfoam near Moss Beach, San Mateo County, California, in a seasonally fallow 9-ha agricultural field (Ceska and Ceska 1999; COSEWIC 2004; Tucker 2010; Buxton 2013; Consortium of Pacific Northwest Herbaria 2021). The California plants have a different morphology from the Vancouver Island plants: the former are more erect, and usually have double-pinnate leaves, while the latter have a decumbent growth form and primarily pinnate leaves (COSEWIC 2004; Buxton 2013). The California plants are not as cold hardy as the British Columbia plants, and flowered about a month earlier in garden experiments involving both species (COSEWIC 2004; Buxton 2013). Phylogenetic analyses suggest that the California plants are a deviant four-petalled population of Limnanthes douglasii (Meyers et al. 2010), and the plants are currently described as the only location of L. douglasii spp. ornduffii (Buxton 2013). Genetic studies are currently in progress at the University of California Botanical Garden to determine the relationship between Macoun’s Meadowfoam in Canada and L. douglasii ssp. ornduffii (Fairbarns pers. comm. 2023).

Morphological description

Macoun’s Meadowfoam is a small annual plant that grows from a fibrous root system (Figures 1 and 2). The plants reach 2 to 5 cm tall, and occasionally up to 15 cm. The fruits are 3-mm-long nutlets that occur in clusters of three or four (occasionally one), initially yellow-green, but becoming light brown. The fruits are in the form of an inverted cone, with tubercles (small, rounded projections) on the tip (Figure 3).

Figure 1. Close-up photo of Macoun’s Meadowfoam. Photo: C. Maslovat (January 23, 2022, Yellow Point).

Figure 2. Young Macoun’s Meadowfoam plant showing root structure (plant was found dug up during surveys). Photo: C. Maslovat (February 5, 2022, Creyke Point).

Figure 3. Nutlets on Macoun’s Meadowfoam plants. Photo: R. Batten (May 3, 2018, Harling Point).

When the species is in flower, it can be easily identified by its simple, four-part white flowers and pinnate leaves (BC CDC 2021). When the species is in fruit, the angular and comparatively large tubercles on the conspicuous nutlets are a key diagnostic feature (COSEWIC 2004, 2010). When lacking flowers, Macoun’s Meadowfoam may be confused with bittercress (Cardamine spp.), Small-flowered Nemophila (Nemophila parviflora) and Meadow Nemophila (Nemophila pedunculata). Macoun’s Meadowfoam can be distinguished from bittercress by its hairless leaves and the presence of fibrous rather than tap roots. Both Nemophila species have leaves that are divided almost to the midrib but are not fully pinnate (that is, not divided into separate leaflets); in addition, Macoun’s Meadowfoam lacks hairs, while both Nemophila species have fine hairs (BC CDC 2021).

Population spatial structure and variability

The B.C. Conservation Data Centre (BC CDC) considers subpopulations separated by more than 500 m, rather than the standard distance of 1 km, to be distinct occurrences. The smaller separation distance was chosen due to the species’ very poor dispersal capability and its small, very discrete habitat units, with little possibility of suitable habitat between them (BC CDC 2007). Some of the subpopulations in the first status report (COSEWIC 1988) were combined in the update status report (COSEWIC 2004), which used 1 km as the separation distance. Some of the subpopulations have been separated in this report due to the implementation of the 500-m separation distance.

Designatable units

No recognized subspecies/varieties or discrete/evolutionary significant populations exist, and therefore no additional designatable units for the Canadian population can be recognized. Consequently, Macoun’s Meadowfoam in Canada is considered to be one designatable unit.

Special significance

Macoun’s Meadowfoam is considered endemic to southern Vancouver Island and the adjacent Gulf Islands. It has not been found in the United States or mainland British Columbia.

The family Limnanthaceae is only represented by two species in Canada: Macoun’s Meadowfoam and False Mermaidweed (Floerkea proserpinacoides). Among the 20 currently recognized global taxa in the family, eight are of conservation concern (Meyers et al. 2010).

White Meadowfoam (Limnanthes alba) is native to California and Oregon, and is grown commercially on a limited scale in the United States, mainly in the state of Oregon (Meyers et al. 2010). It is prized for its long-chain seed oil, which is stable at high temperatures and pressures (Dole and Sun 1992; Meyers et al. 2010). The oil is used in a range of products, from cosmetics to detergents, and the seed meal has possible applications in insecticides, herbicides, anti-cancer drugs and soil nitrogen amendments (Velasco et al. 2011; Intanton et al. 2014; Carpenter et al. 2018; Türkmen and Myrold 2018; Agerbirk et al. 2022). Other Limnanthes species may provide useful genetic material in breeding programs to develop crops (Dole and Sun 1992; Knapp and Crane 1999; Meyers et al. 2010).

Distribution

Global range

Macoun’s Meadowfoam is found on southeastern Vancouver Island and adjacent islands in British Columbia. It is geographically isolated from other members of the genus; the closest congener is Douglas’ Meadowfoam, which is native to California and Oregon (Morin 2021). Douglas’ Meadowfoam is grown as a horticultural plant in British Columbia, and may be found as an escapee in disturbed soils (iNaturalist 2023).

Canadian range

In Canada, Macoun’s Meadowfoam ranges from East Sooke to Victoria, including the adjacent Inskip, Chatham and Trial islands. Most of the subpopulations are located between East Sooke Regional Park and Gordon Head, 33 km apart. From Victoria, the species’ range extends north to Saltspring, Gabriola, and Hornby islands and Yellow Point. Most of the subpopulations occur along shorelines, creating a linear distribution that is correlated with the location of suitable habitat (Figure 4).

Figure 4. Map showing the range of the global population of Macoun’s Meadowfoam. Prepared by A. Filion, Scientific and GIS Project Officer, Environment and Climate Change Canada, Gatineau, Que.

Within the natural range, several subpopulations are now being, or have been, managed or manipulated as follows:

• Whirl Bay. The largest subpopulation on Whirl Bay was discovered in an ammunition depot firebreak in 2010. The firebreak is tilled biannually (in late spring and early fall) to reduce fuel loads, which creates patches of bare soil and areas of shallow standing water due to the impermeable clay soils. The fall tilling creates safe sites for Macoun’s Meadowfoam to germinate, and the plants flower and set seed prior to the spring tilling. These site management practices create atypical habitat and ensure a lack of competition, supporting the germination and growth of unusually abundant and large Macoun’s Meadowfoam plants (Garry Oak Ecosystems Recovery Team Plants at Risk Recovery Implementation Group 2011; Miskelly pers. comm. 2022). It has been suggested that these large plants are similar to L. douglasii ssp. ornduffii (Fairbarns pers. comm. 2023), but no genetic studies have been conducted. Management of some portions of the firebreak has changed since 2012, and some areas have become grassier, which has resulted in fewer plants. In areas that are managed in the same way as in the past, the plants continue to be abundant and were estimated to number over 4 million in 2012 (see Abundance). This subpopulation is managed, not manipulated, and is included as part of the wildlife species, and the plants are included in the Canadian population for application of criteria. The plants have seeded in naturally
• Fort Rodd Hill. The natural subpopulation has been enhanced through habitat restoration work involving hand tilling, seeding and the removal of invasive perennial grasses. The seeds came from the original Fort Rodd Hill subpopulation (Fisk pers. comm. 2023). This work has increased the number of plants in the subpopulation, although it likely would have persisted without manipulation. This subpopulation is included as part of the wildlife species, and the plants are included in the Canadian population for application of criteria
• Uplands Cattle Point. Approximately one teaspoon of seeds were sown in Uplands Park to reintroduce plants to an area where they had previously occurred. No site preparation was done and, although plants persisted at the site for a couple of years after sowing, they disappeared shortly thereafter (Thomas pers. comm. 2022). No plants from this reintroduction have survived to be included in the Canadian subpopulation, and only the natural subpopulation on Cattle Point in Uplands Park persists

Extent of occurrence and area of occupancy

The extent of occurrence (EOO), based on the minimum convex polygon drawn around the extant observations, is 4,723 km². The distribution has substantial gaps, with the largest one, 80 km, separating the Hornby Island and Gabriola Island subpopulations. The index of area of occupancy (IAO), based on a 2 km x 2 km grid drawn over the extant observations, is 100 km².

Search effort

Macoun’s Meadowfoam was first collected in 1875 by John Macoun, who described the locality as “in ditches at Victoria,” on Vancouver Island. The exact location of this collection is not known. Other historical collections, including those recorded as “Dallas Road,” “Victoria Breakwater” (Newcombe’s collections in the 1930s) and West Burnside Road (Macoun 1908) could not be relocated and are presumed extirpated. A 1952 monograph published by Mason on the genus Limnanthes was used to document some of the early collections in the Victoria area (Mason 1952, in COSEWIC 2004). Limited collection of the species occurred from the 1950s to the early 1970s, but the survey effort increased between 1972 and 2003, primarily due to the efforts of botanists Adolf and Oluna Ceska, which resulted in the discovery of many new subpopulations (Ceska and Ceska 1999).

Prior to the 2004 status report (COSEWIC 2004), Ceska and Ceska (1999) completed 150 field trips to revisit known subpopulations of Macoun’s Meadowfoam and to look for new ones. All subpopulations except one or two were surveyed and the size of each subpopulation was counted or estimated. From 1988 to 2003, seven new subpopulations were discovered, including many new sites on Department of National Defence (DND) lands (COSEWIC 2004).

Surveys for the present status report update focused on subpopulations that had not been recently surveyed, in order to confirm their persistence and assess threats. Owing to resource constraints, not all subpopulations were resurveyed and no search effort was expended on finding new subpopulations. Since the 2004 status report, two new subpopulations have been discovered (Whirl Bay in 2010 and Turkey Head in 2021) and a third subpopulation (Duntze Head), which was not previously included in the BC CDC database, has been added.

New subpopulations may remain to be found on remote Gulf Islands or on coastlines of Vancouver Island that have not been visited by botanists familiar with the species (COSEWIC 2004), most likely on private property that has not been previously surveyed.

Habitat

Habitat requirements

Macoun’s Meadowfoam occurs at sites in the coastal dry belt of British Columbia, where the maritime climate results in mild, wet winters and warm, dry summers. Plants are found in open areas or light, open forests, in microsites that are either wet or shallowly submerged in the winter and that dry up completely in the summer, with short or sparse vegetation (COSEWIC 2004). These catchment habitats are fed by surface rainwater and subsurface seepage, and the minimum canopy opening required to allow sufficient light to the plants is 20 m from the plants in all directions (Parks Canada Agency 2013).

The habitat is strongly maritime-influenced: the salt spray and shallow soils limit competing tree and shrub growth (Figures 5 and 6). Most sites are along the shoreline, within 200 m of the ocean, where much of the habitat has been historically altered by development. However, a few anomalous sites (Montreul Hill, Pearson College and Government House) are located farther inland, within 2 km of the shoreline, where shallow soils on rock outcrops and seepages limit tree growth sufficiently to create suitable habitat. The elevation of most sites is 0 to 35 m above sea level, but at Montreul Hill, the species occurs at elevations as high as 190 m above sea level (BC CDC 2022).

Figure 5. Macoun’s Meadowfoam plants (front, centre) growing in standing water in vernal pool. Photo: C. Maslovat (January 22, 2022, Harling Point).

Figure 6. Ryan Batten, Joanne Levesque, and Marc Lefrancois count plants at William Head Correctional Facility. Photo: C. Maslovat (February 18, 2022, Quarantine Cove).

To germinate, the plants require saturated soils during the winter months, with the water table at, or up to 5 cm above, the soil surface. Moisture is retained at these sites until the end of April, and they dry up completely over the summer. The plants grow in the following habitat types:

1. vernal pools created from depressions in the bedrock lined with shallow soil
2. intermittent seepage on open slopes along bedrock fractures that are impermeable and retain water
3. wet depressions and ends of seepage streams where seabirds gather and feed and that are extremely rich in nutrients
4. depressions and seepages in light, open mixed forests of Douglas-fir (Pseudotsuga menziesii), Garry Oak (Quercus garryana), Arbutus (Arbutus menziesii), Rocky Mountain Juniper (Juniperus scopulorum) or Lodgepole Pine (Pinus contorta) (COSEWIC 2004). Most of the subpopulations are in Garry Oak and associated ecosystems

Macoun’s Meadowfoam plants are shade intolerant; in sites where plants grow among tall grasses in open forests, the plants are thin and elongated and produce less seed (COSEWIC 2004).

The bedrock is volcanic at most sites, although the substrate is sandstone on Gabriola and Hornby islands and at Yellow Point. Most sites do not have surficial glacial till, although a thin layer of glacial till (less than 5 cm) is found at the sites of two subpopulations, Saxe Point and Becher Bay (COSEWIC 2004). The shallow soils range from a few centimetres to 30 cm deep, and are acidic (pH < 5.5) and rich in humus and nutrients. Several subpopulations are located on substrate enriched by seabird guano deposits. Plants are more viable in shallow soils (< 4 cm), because deeper soils support perennial grasses or invasive shrubs that can outcompete Macoun’s Meadowfoam (COSEWIC 2004).

Habitat trends

Suitable habitat is declining throughout the species’ range; a comparison of current and historical conditions suggests that over 95% of Garry Oak ecosystems have been lost (MacDougall et al. 2004; Lea 2006). Shoreline habitat is particularly desirable for development, and most maritime meadows have been lost or degraded. Invasive non-native species, including Scotch Broom (Cytisus scoparius) and non-native grasses, are further degrading the remaining habitat.

Biology

The information in the following section is derived from the previous COSEWIC status report (2004), supplemented with more recent work described in the literature and by information from local species-at-risk biologists who propagate the species for restoration purposes.

Life cycle and reproduction

Under nursery conditions, Macoun’s Meadowfoam germinates from mid-September to mid-October (Fisk pers. comm. 2022) but, under natural conditions, seeds probably continue to germinate throughout the winter. Mild winters and high precipitation are required for germination, survival and reproduction (COSEWIC 2004). Plants are most easily observed in December and January, because the leaves are distinctive and the surrounding vegetation is minimal; like other winter annuals, the plants grow at a time when most other plants are dormant (COSEWIC 2004). Plants flower from March to early May (COSEWIC 2004; Tucker 2010). Nutlets have been observed as early as April and mature by the beginning of June (Maslovat and Batten, pers. obs. 2022).

Other Limnanthes species are self-compatible, with a breeding system ranging from cleistogamy (self-pollination) to chasmogamy (cross-pollination) (Kesseli and Jain 1985). Some populations of other Limnanthes species are gynodioecious, with sterile males co-occurring with hermaphrodite plants (Kesseli and Jain 1984). A proportion of the plants may outcross: in other Limnanthes species, self-pollinated seed ranged from < 2% to over 60% (Kesseli and Jain 1985); however, these species have larger, showier flowers than Macoun’s Meadowfoam. Macoun’s Meadowfoam is entirely self-pollinated/self-fertilized in cultivation (Ornduff 1971).

Seeds have been kept alive in low-humidity cold storage for approximately 15 years (Knapp and Crane 1999). Seed dormancy in vernal pool species, including other Limnanthes species, is influenced by seasonal hydrology and prolonged soil drying (Colyer and Howard 2021). The optimal temperature for germination in Limnanthes is 5 to 15 °C, and seeds subjected to temperatures higher than 21 °C revert to secondary dormancy, with higher levels of dormancy associated with prolonged high temperatures (Toy and Willingham 1967).

Experimental planting of Macoun’s Meadowfoam seed under nursery conditions resulted in low (6%) germination rates (COSEWIC 2004). Parks Canada had germination rates of about 30% when fresh seed was sown in the fall in containers, on top of potting mix and under a thin covering of peat moss (Fisk pers. comm. 2022). This low germination rate suggests that the species staggers germination, relying on seed banks in unfavourable years.

Plants will re-seed in nursery containers. Deeper, richer soil with minimal competition results in larger plants that produce more seed than when grown in thinner, poorer soil with more competition (Fisk pers. comm. 2022). Under field conditions, richer soil would result in increased competition from other species.

Physiology and adaptability

White Meadowfoam seed oil is rich in triglycerides, and plants in the Limnanthaceae family have high levels of glucosinolates (Carpenter et al. 2018; Agerbirk et al. 2022). It is unknown how these compounds impact the physiology of the genus, but, in Brassica spp., glucosinolates are involved in protecting plants from stress associated with low temperatures (Ljubej et al. 2021).These compounds likely play a similar role in Macoun’s Meadowfoam, a winter annual that may spend weeks under the snow.

Dispersal and migration

Macoun’s Meadowfoam produces up to four large nutlets per flower. Nutlet dispersal occurs by water over short distances; the shape of the tubercles on the nutlets may extend flotation time, allowing seed deposition in the preferred moisture gradient of vernal pools (Hauptli et al. 1978). Bird dispersal, which has been proposed for other vernal pool species, has not been confirmed in this species (Sloop et al. 2011). Intense tilling at the location of the Fort Rodd Hill subpopulation resulted in seeds being washed out in areas with slopes (Fisk pers. comm. 2022), which further suggests seeds may be dispersed through water movement.

Severe fragmentation

The required vernal pool/seepage habitat is naturally fragmented and habitat patches in subpopulations are separated by distances greater that the species can reasonably be expected to disperse, given the limited dispersal mechanisms.

The viability of most of the subpopulations has been assessed as fair to good in the recovery strategy (Parks Canada 2013).

Interspecific interactions

There are no known interspecific interactions for Macoun’s Meadowfoam. Self‑pollination in other Limnanthes species appears to require pollen transmission by insects (Kesseli and Jain 1985). Other Limnanthes species are pollinated by miner bees (Andrena spp.), non-native European Honeybees (Apis mellifera) (Kesseli and Jain 1984; Leong and Thorp 1999; Runquist 2012), flies (syrphid and other unidentified small flies), and generalist bees (Lasioglossum, Dialictus, Osmia and halictids) (Runquist 2013). Gall wasps and midges (family Cecidomyidae) have been observed on Macoun’s Meadowfoam (Winchester pers. comm. 2022).

In other Limnanthes species, bees are the primary pollinators, due to the concealed position of the nectaries at the base of the sepals and petals (Link 1992). In the case of Macoun’s Meadowfoam, the impact of habitat fragmentation on pollinator abundance is not understood.

Herbivory is presumed to be limited due to the species’ small size, and was not observed during the 2022 surveys.

Animals can cause soil disturbance and trampling, and it is unclear if this creates or degrades Macoun’s Meadowfoam habitat. River Otter (Lontra canadensis) slides exposing bare soil were found at the sites of several subpopulations, and Canada Geese (Branta canadensis), which create soil disturbance and compaction, were also present (Maslovat pers. obs. 2022).

Population size and trends

Sampling effort and methods

Prior to drafting this status report update, the report writers identified known subpopulations by reviewing the BC CDC and NatureServe websites (NatureServe 2021; BC CDC 2022) and by querying BC CDC staff. To prioritize sites for surveys, the authors contacted local agencies with known subpopulations (Parks Canada Agency and Natural Resources Canada) and local botanists who work in areas with Macoun’s Meadowfoam to determine which subpopulations had recently been surveyed. Priority was given to areas that had not been recently monitored and where site access could be secured. Twelve subpopulations were surveyed by the report writers prior to the status report update. At each of these sites, the number of plants was counted and an assessment of threats was made.

Abundance

Macoun’s Meadowfoam is known from 37 element occurrences (EOs) (36 listed by the BC CDC plus one not yet listed) corresponding to the same number of subpopulations, of which one is considered historical, three are extirpated, and two are presumed extirpated, leaving 31 extant subpopulations (Table 1). About a third of these subpopulations have more than one site (distinct polygon greater than 5 m but less than 500 m from other plants).

From 1988 to 2003, four subpopulations were discovered to be extirpated, and seven new subpopulations were found. From 2003 to 2022, three new subpopulations were discovered, while two were possibly extirpated. The increase in subpopulations reflects the greater search effort expended on this species, as well as the change in the separation distance between subpopulations.

Most plants are concentrated in one large subpopulation (Whirl Bay), which is in a maintained firebreak. Although the occurrence was discovered in 2010, plant numbers were only counted once, in 2012, when the occurrence was estimated to contain over 4 million plants. This number was based on counts in random 1-m² plots, which were multiplied by the total area covered by the plants, providing a rough estimate of 4.2 million (95% confidence interval of 2.2 to 6.5 million) (Miskelly pers. comm. 2022). The management practices used in some portions of the firebreak have changed since 2012, and the density of grasses has increased in some areas, which has resulted in fewer plants; in areas that are managed as they were in the past, the plants continue to be abundant. There has been no new estimate of the total number of plants in the Whirl Bay subpopulation since 2012 (Miskelly pers. comm. 2023).

An additional 13 subpopulations each have over 1,000 plants (Beecher Bay, Church Point, Rocky Point, Mary Hill [southeast and southwest slopes], Hornby Island, Fort Rodd Hill, Yew Point, Harling Point, Trial Islands, Uplands – Cattle Point, Yellow Point, Saltspring Island and Turkey Head), but the remainder have very few (from 20 to 392 plants). Excluding the Whirl Bay subpopulation and based on the most recent count data, the total number of plants in all other subpopulations is estimated to be between 70,000 and 74,600.

Fluctuations and trends

As in other species of annuals, plant numbers in Macoun’s Meadowfoam subpopulations can vary significantly from year to year. Although previous survey efforts showed that plant numbers in the subpopulations tended to be consistent from year to year, remaining within the general categories of small (1 to 50 plants), medium (50 to 200 plants) or large (> 200 plants) (COSEWIC 2004), more recent monitoring suggests numbers can fluctuate by several orders of magnitude. However, the seed bank stabilizes the population. so that extreme fluctuations do not occur.

The Ruckle Park subpopulation has been monitored consistently every year from 2014 to 2022 by the same surveyor. Total numbers have ranged from 274 to 4,272, but this includes newly discovered sites in the subpopulation. One of the largest sites had between 4 and 1,709 plants over this time period (Figure 7; Maslovat 2022).

Figure 7. Graph showing fluctuations in numbers of Macoun’s Meadowfoam plants over time at the group campground site at Ruckle Park.

The Fort Rodd Hill subpopulation has also displayed large fluctuations in numbers, ranging from approximately 500 plants in 2015 to 3,500 plants in 2021. This increase in abundance is attributed to habitat restoration efforts that began in 2016 and have included hand tilling, seeding and using carpet knives to remove invasive perennial grasses (Fisk pers. comm. 2022).

By the 2003 report update, among the 52 occurrences that were reported as “populations” in the 1988 status report, 29% (15 occurrences) had disappeared, 27% (14) had declined, 19% (10) had remained roughly the same, and 23% (12) had increased. The majority of subpopulations that were extirpated were small and, in most cases, had been outcompeted by invasive perennial grasses (COSEWIC 2004).

Between 2003 and this report, among the remaining 31 extant subpopulations, 22% (7 subpopulations) were presumed to have a stable trend; 13% (4), a stable or increasing trend; 35% (11), an increasing trend; and 6% (2), a declining trend (Table 2). Trends could not be determined in 23% (7) due to insufficient data. However, the higher plant counts recorded recently may be due to the more intensive search effort, which resulted in new sites being found in each subpopulation, although at least three subpopulations have lost sites. Annual fluctuations and a lack of annual monitoring data make trends difficult to confirm.

Rescue effect

There is no possibility of rescue because Macoun’s Meadowfoam is endemic to Canada (southeastern Vancouver Island and the Gulf Islands).

Threats and limiting factors

Threats

The direct threats facing Macoun’s Meadowfoam were assessed and organized based on the IUCN-CMP (International Union for the Conservation of Nature – Conservation Measures Partnership) unified threats classification system (Master et al. 2012, based on Salafsky et al. 2008). Threats are defined as the proximate activities or processes that directly and negatively affect the population. Results for the impact, scope, severity and timing of threats are presented in tabular form in Appendix 1.

The Whirl Bay subpopulation is maintained due to tilling operations to create a firebreak for an ammunition depot. An end to this practice would impact 98% of the Canadian population. However, since there is no indication of a change in this management practice in the future, the subpopulation was excluded from the threat assessment in order to better understand the impact of threats on the natural subpopulations.

The overall threat impact was assessed as Medium. The numbers associated with the threats listed below correspond to the IUCN threat numbers; the Threats Calculator for the species can be found in Appendix 1.

11.2 Climate change and severe weather: droughts (high - low impact)

High levels of water accumulation in the winter are required to stimulate germination in the species. Prolonged Arctic outflow events— which produce sub-zero temperatures, high winds and low humidity—can cause dehydration and death in winter annuals, including Macoun’s Meadowfoam (Fisk pers. comm. 2022). Even in warm temperatures, unseasonably dry periods in the fall or early winter can damage seedlings that germinate too early after the fall rains (COSEWIC 2004). Unseasonable droughts in early spring can negatively impact seed set, but the impact of summer droughts is negligible because seed set has already occurred. Climate change is predicted to increase annual variations in precipitation in Puget Sound (Mauger et al. 2015). The impact of Temperature Extremes (11.3) or Storms and Flooding (11.4) related to climate change is unknown. Low winter temperatures can delay germination, and frosts can kill plants at the germinant stage. More extreme storms could cause waves and salt spray to reach some subpopulations, but the impact of this is unknown.

8.1 Invasive and other problematic species and genes: invasive non-native/alien species/diseases (medium - low impact)

Canada Geese (Branta canadensis) were first introduced to Vancouver Island in the late 1920s and early 1930s for the purpose of hunting; numbers have been increasing since the mid-1980s and large resident subpopulations are now present (Dawe and Stewart 2010). These birds cause soil disturbance and compaction on shorelines and in Garry Oak ecosystems (Maslovat pers. obs. 2022), which could result in the degradation of Macoun’s Meadowfoam habitat. Invasive non-native plants are considered under 7.3 Other Ecosystem Modifications.

1.1 Residential and commercial development: housing and urban areas (low impact)

Macoun’s Meadowfoam habitat has declined because of development pressure in the areas of some subpopulations. Historical subpopulations have disappeared due to urban development, which encompasses activities such as deck construction, subdivision/house construction, burning, installation of water pipes and gravel filling. Four subpopulations and multiple sites within subpopulations are confirmed to have been extirpated, or likely to have been so, since 1988. This type of development damages the habitat directly and can also alter the hydrologic regime, impacting the seepages on which Macoun’s Meadowfoam depends for survival (COSEWIC 2004). It is predicted that future threats associated with development will be minimal, because most known subpopulations occur on publicly owned land; when the Whirl Bay subpopulation is excluded, only 2% of plants are found on private land.

1.2 Residential and commercial development: commercial and industrial areas (low impact)

Subpopulations on DND lands may be impacted by the construction of facilities or other types of development. Subpopulations on DND lands account for 37% of the population (excluding the Whirl Bay subpopulation); however, Macoun’s Meadowfoam plants are in no-go zones on DND lands, and staff are aware of the plants’ localities.

6.1 Human intrusions and disturbance: recreational activities (low impact)

Macoun’s Meadowfoam grows in public parks or recreational areas, where the habitat is heavily trampled. Light trampling appears to be beneficial to the species by limiting competition from invasive plants; the impact is low during the winter and early spring months when areas are too wet for extensive use, but high in the summer during periods of heavy recreational use when invasive grasses can be suppressed by trampling (COSEWIC 2004). Excessive trampling can also result in compacted soils that, though they can still support Macoun’s Meadowfoam, result in smaller plants that may produce less seed (Maslovat pers. obs. 2022).

Recreational activities can also spread invasive plants, including Field Burweed (Soliva sessilis), Subterranean Clover (Trifolium subterraneum) and Bulbous Bluegrass (Poa bulbosa), which can increase competition for moisture and light in seepage habitat (see 7.3 Other Ecosystem Modifications).

7.3 Natural systems modifications: other ecosystem modifications (low impact)

Invasive non-native plants represent a major threat to Macoun’s Meadowfoam, but currently the impact is assessed as Low. Non-native plants represent almost half of all vascular plant species and now make up the dominant herbaceous layer in Garry Oak and associated ecosystems (COSEWIC 2004).

Invasive shrubs grow in areas adjacent to Macoun’s Meadowfoam habitat, but can degrade conditions in the habitat itself by casting shade, altering the vegetation structure and changing soil chemistry, potentially creating more favourable conditions for other invasive species (COSEWIC 2004; Slesak et al. 2016). They include Scotch Broom, which is present in almost a third of subpopulations, and Gorse (Ulex europaeus), which is present in two subpopulations. English Ivy (Hedera helix) appears to have caused the extirpation of one of the three sites making up the Gordon Head subpopulation (Maslovat pers. obs. 2022). Native Salmonberry (Rubus spectabilis) appears to be outcompeting Macoun’s Meadowfoam at one site (Miskelly pers. comm. 2022).

Invasive non-native perennial grasses now dominate the herb layer in Garry Oak and associated ecosystems. Species including Common Velvetgrass (Holcus lanatus), Colonial Bentgrass (Agrostis capillaris), Redtop (A. gigantea), Orchard Grass (Dactylis glomeratus), Perennial Ryegrass (Lolium perenne), Sweet Vernalgrass (Anthoxanthum odoratum), Creeping Bentgrass (Agrostis stolonifera), Crested Dogtail Grass (Cynosurus cristatus), Bulbous Bluegrass and Kentucky Bluegrass (Poa pratensis) compete directly with Macoun’s Meadowfoam by soaking up moisture and decreasing the amount of open soil in depressions and seepages over time. Non-native annual grasses— including Hedgehog Dogtail Grass (Cynosurus echinatus), Early Hairgrass (Aira praecox), Silver Hairgrass (A. caryophyllea), Brome Fescue (Vulpia bromide’s), Rat-tail Fescue (V. myuros), Soft Brome (Bromus hordeaceus) and Bald Brome (Bromus racemosus)—create thatch accumulation in the depressions. This increases soil organic matter, which promotes vegetation growth, and results in drier pools with less suitable habitat for Macoun’s Meadowfoam. Invasive grasses were responsible for the loss of seven sites (out of 18 sites lost) from 1988 to 2003 (COSEWIC 2004).

Invasive non-native forbs also compete with Macoun’s Meadowfoam. Subterranean Clover is present in many subpopulations (COSEWIC 2004; Maslovat pers. obs. 2022), as is Bur Chervil (Anthriscus caucalis). Field Burweed, a non-native plant first collected in British Columbia in 1996 (Lomer 1997), is a persistent threat at Ruckle Park and Uplands Park (Maslovat pers. obs. 2022). These non-native species require habitat with wet depressions, although they prefer the slightly drier conditions that occur at the edge of core Macoun’s Meadowfoam habitat (COSEWIC 2004).

10.2 Geological events: earthquakes/tsunamis (unknown impact)

Low-elevation areas could be hit by tsunamis; however, the impact is unknown. Vancouver Island is in an earthquake zone, but even a large earthquake is unlikely to impact the habitat of this plant.

Limiting factors

Macoun’s Meadowfoam is restricted to specific habitat that is naturally rare in the landscape. Biophysical attributes that may be limiting include the availability of open soil and sufficient moisture in seepages or pools during the species’ growing season (from October to March).

The dispersal of nutlets is limited, which prevents subpopulations from expanding and new subpopulations from being established.

Macoun’s Meadowfoam plants are self-compatible, and sites are geographically isolated in remnant habitat fragments, with little pollen or seed dispersal between subpopulations. The impacts of genetic isolation (for example, inbreeding depression, genetic drift and decreased adaptability to environmental change) on Macoun’s Meadowfoam are unknown. Low levels of genetic diversity due to gene flow barriers have been observed in Limnanthes species in California that are similarly restricted to isolated vernal pool habitat. Germination from historical seed banks may return important genetic diversity to subpopulations (Sloop et al. 2011).

Number of locations

There are 31 extant subpopulations and, based on the threats assessment for the Canadian population, at least 36 (based on primary threats) and most likely 39 locations, as EO #17 has multiple private landowners (Table 3). Within locations, the number of sites ranges from 1 to 26.

Protection, status and ranks

Legal protection and status

In Canada, Macoun’s Meadowfoam was listed as Threatened on Schedule 1 of the Species at Risk Act on August 15, 2006 (Government of Canada 2011). It is not listed under the Convention on International Trade in Endangered Species (CITES 2022) and has not been assessed by the International Union for Conservation of Nature and Natural Resources (IUCN 2022).

Non-legal status and ranks

Macoun’s Meadowfoam is considered Imperiled (S2?^{Footnote 1}) in British Columbia and Imperiled (N2?) in Canada. Globally, it was ranked Imperiled (G2?) in 2020 (NatureServe 2021).

Habitat protection and ownership

Ownership of Macoun’s Meadowfoam subpopulations is listed in Table 3. Among the remaining extant sites, 11 sites are federally managed (eight by DND, two by Parks Canada Agency, and one by Corrections Canada), three are on First Nations’ Reserve lands (plus a fourth presumed extirpated), five are provincially managed (two BC Parks; one Ecological Reserve; one Government House; one provincial telecommunications lease), eight are in regional parks, and nine are occurrences held by private landowners (plus two extirpated and one presumed extirpated). These numbers do not add up to 31 extant subpopulations, because some subpopulations with multiple sites have more than one type of land tenure.

Critical habitat has been identified and mapped for 30 subpopulations, and the Government of Canada is in consultations with Songhees Nation to identify critical habitat at an additional site (Chatham Islands, Heritage Point) (Parks Canada Agency 2013).

The Trial Islands Ecological Reserve was established to protect Macoun’s Meadowfoam (COSEWIC 2004).

Subpopulations on private land are not protected, except for one site that has a conservation covenant registered on the land title; however, the species is presumed extirpated at this site (Fairbarns 2017; Maslovat pers. obs. 2022).

Acknowledgements

The status report writer would like to thank Laura Matthias for providing the cover photo of the species for this status report. Much appreciation goes to Nathan Fisk, James Miskelly, Matt Fairbarns and Wylie Thomas for counting plants and providing information on subpopulations. I would also like to thank Joanne Levesque and Marc Lefrancois (Corrections Canada), Jill Robinson and Jeanette Mollin (Capital Regional District Parks), Erica McClaren (BC Parks), and private landowners for allowing access to their sites for surveys. My thanks also go to Alain Filion for preparing the distribution map and calculating the extent of occurrence (EOO) and index of area of occupancy (IAO) for this report. I am very grateful to the people and agencies who reviewed drafts of this report, including Bruce Bennett (Yukon Conservation Data Centre), Sean Blaney (Atlantic Canada Conservation Data Centre), Mannfred Boehm (University of British Columbia), Syd Cannings (Canadian Wildlife Service), Brenda Costanzo (Province of British Columbia, retired), Nathan Fisk (Parks Canada Agency), Gina Schalk (Environment and Climate Change Canada) and Linda Takahashi (Canadian Wildlife Service). Many thanks go to Del Meidinger for his assistance in supporting this document to completion and to all the authorities contacted who provided knowledge and expertise on the species.

Authorities contacted

• Asencio, Shannon. Collections Manager. National Collection of Vascular Plants, Agriculture and Agri-Food Canada. Ottawa, Ontario
• Batten, Ryan. Botanist. British Columbia Conservation Data Centre, Beacon Botanical Research. Victoria, British Columbia
• de Forest, Leah. Species Conservation Specialist. Parks Canada Agency. Halifax, Nova Scotia
• Doubt, Jennifer. Curator, Botany. Canadian Museum of Nature. Ottawa, Ontario
• Fairbarns, Matt. Botanist. Aruncus Consulting. Victoria, British Columba
• Filion, Alain. Scientific and GIS Project Officer. COSEWIC Science Support, Canadian Wildlife Service, Environment and Climate Change Canada. Gatineau, Quebec
• Fisk, Nathan. Resource Management Officer. Parks Canada. Colwood, British Columbia
• Govindarajulu, Purnima. Unit Head. Species Conservation Unit, Conservation Science Section, Ecosystems Branch, Ministry of Environment and Climate Change Strategy. Victoria, British Columbia
• Kroeker, Nicole. Species Conservation Implementation Manager. Parks Canada. Victoria, British Columbia
• Lake, Randal. Head, Regulatory Affairs. Canadian Wildlife Service, Environment and Climate Change Canada. Nanaimo, British Columbia
• McClaren, Erica. Conservation Specialist. West Coast Region, BC Parks, Ministry of Environment and Climate Change Strategy. Black Creek, British Columbia
• Miskelly, James. Forestry Officer. Pacific Forestry Centre, Natural Resources Canada. Victoria, British Columbia
• Penny, Jenifer. Program Botanist. B.C. Conservation Data Centre, Ministry of Water, Land and Resource Stewardship. Victoria, British Columbia
• Pollard, Adriane. Manager of Environmental Services. District of Saanich. Saanich, British Columbia
• Robinson, Jill. Senior Conservation Biologist. CRD Parks. Colwood, British Columbia
• Roemer, Hans. Botanist. Victoria, British Columbia
• Sadler, Kella. Head, Species at Risk Recovery. Canadian Wildlife Service, Environment and Climate Change Canada. Nanaimo, British Columbia
• Schnobb, Sonia. Program Support Specialist. COSEWIC Secretariat. Gatineau, Quebec
• Shepherd, Pippa. Species Conservation and Management Ecosystem Scientist III. Parks Canada. Sidney, British Columbia
• Straka, Jason. Program Ecologist. B.C. Conservation Data Centre, Ministry of Water, Land and Resource Stewardship. Victoria, British Columbia
• Thomas, Wylie. Botanist. Victoria, British Columbia
• Wu, Jenny. Scientific Project Officer. Environment and Climate Change Canada. Gatineau, Quebec

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Biographical summary of report writer(s)

Carrina Maslovat works as a botanist specializing in plant communities at risk, primarily Garry Oak ecosystems. She has inventoried rare plants in regional, municipal, federal and provincial parks, finding new subpopulations of species at risk and monitoring the abundance and vitality of rare plant populations over time. She has developed management plans for nature reserves, created best management practices to minimize impacts to species at risk, and designed ecological restoration projects to provide habitat for species at risk. She is the writer of six COSEWIC status reports, four status report updates and several recovery planning documents.

Ryan Batten is a botanist and plant ecologist with 15 years of experience specializing in rare plants, wetlands and biodiversity inventory. He brings a broad floristic knowledge from conducting field work in British Columbia, Alberta, Saskatchewan, Ontario and Nunavut. He is an active member of the B.C. Flora Update Committee and has been affiliated with the Royal B.C. Museum Herbarium for the last decade. In 2019, he prepared the status ranks for all of B.C.’s vascular plants for the federal government’s General Status of Wild Species in Canada program. Ryan works frequently with the B.C. Conservation, Data Centre where he spends most of his time drafting conservation status reports, mapping the ranges of rare species and providing training on the NatureServe methodology for status assessment. His current research interests include geospatial floristics, human-mediated dispersal and traits of rarity.

Collections examined

• Canadian Museum of Nature (CAN): CAN10090418 (Macoun 1875) TYPE or ISOTYPE; CAN79440 (Macoun 1893); CAN79441 (Macoun 1893); CAN79436_x (Macoun 1908); CAN79436_y (Macoun 1908); CAN79437_x (Macoun 1908); CAN79437_y (Macoun 1908); CAN511446 (Macoun 1908); CAN511447 (Macoun 1908); CAN79438 (Newcombe 1919); CAN79439 (Newcombe 1919); CAN401307 (Harrison 1966)
• Consortium of Pacific Northwest Herbaria (accessed online): All specimens listed in the collection of origin. NY (William and Linda Steere Herbarium) (Macoun 1893); WTU (University of Washington Herbarium) (Calder 1961); WTU (Melburn 1963); WTU (Armstrong 1975)
• Department of Agriculture, Ottawa (DAO): 28505 (Calder and MacKay 1961); 28917 (Calder and MacKay 1961); 28917 (Calder and MacKay 1961); no number (Melburn 1961); 12576 (Douglas 1992)
• Royal British Columbia Museum (V): V042223 (Macoun 1890); V003185 (Anderson 1900); V042219 (Newcombe 1914); V042222 (Newcombe 1915); V042220A (Newcombe 1917); V042221 (Newcombe 1917); V042224 (Newcombe 1919); V042225 (Newcombe 1919); V042226 (Newcombe 1919); V042227 (Newcombe 1919); V049847 (Newcombe 1919); V005573 (Carter 1919); V007396 (Hardy 1924); V007818 (Hardy 1926); V022784 (Hardy 1952); V022785 (Hardy 1952); V101742 (Melburn 1958); V062462 (Harrison 1973); V156407 (Ceska 1973); V077413 (Parker 1974); V156408 (Ceska 1974); V156409 (Ceska 1974); V156417 (Ceska 1974); V156418 (Ceska 1974); V156419 (Ceska 1974); V156420 (Ceska 1974); V156421 (Ceska 1974); V156441 (Ceska 1974); V069296 (Brayshaw 1974); V156442 (Ceska 1975); V094494 (Pojar 1976); V156405 (Ceska 1976); V156406 (Ceska 1976); V135973 (Douglas 1976); V156412 (Ceska 1977); V156414 (Ceska 1977); V156423 (Ceska 1977); V156424 (Ceska 1977); V156425 (Ceska 1977); V156426 (Ceska 1977); V156427 (Ceska 1977); V156428 (Ceska 1977); V156429 (Ceska 1977); V156430 (Ceska 1977); V156423 (Ceska 1977); V156433 (Ceska 1977); V156434 (Ceska 1977); V156435 (Ceska 1977); V156436 (Ceska 1977); V156437 (Ceska 1977); V156438 (Ceska 1977); V1565439 (Ceska 1977); V156440 (Ceska 1977); V156463 (Ceska 1977); V118459 (Ceska 1977); V087200 (Ceska 1977); V156415 (Pojar 1977); V156411 (Ceska 1978); V156413 (Ceska 1978); V135972 (Douglas 1978); V157786 (Ceska 1988); V157788 (Ceska 1988); V157802 (Ceska 1988); V177147 (Ceska 1989); V157923 (Douglas 1992); V158046 (Douglas 1992); V156464 (Ceska 1993); V164375Y (Ceska 1994); V206225 (Douglas 1998); V178624 (Ceska 2000); V218052 (Parnis 2009); V218020 (Miskelly 2014); V218020”B” (Miskelly 2014)
• University of British Columbia (UBC): V45426 (Henry 1913); V242452 (Carter 1919); V130492 (Schofield 1970); V146296 (Parker 1974); V212177 (Douglas 1992); V238548 (Manton 2010); V216889 (Ceska 2000)

Appendix 1. Threats calculator for Macoun’s Meadowfoam

Threats assessment worksheet

Species or rcosystem scientific name: Macoun’s Meadowfoam - Limnanthes macounii

Date: 2022-10-02

Assessor(s): Del Meidinger (facilitator, Co-chair); Bruce Bennett (Co-chair); Carrina Maslovat and Ryan Batten (report writers); James Miskelly (NRCan); Nathan Fisk (Parks Canada); Wylie Thomas (Botanist); Matt Fairbarns (Botanist); Syd Cannings and Linda Takahashi (CWS); Mannfred Boehm, Brenda Costanzo, Varina Crisfield, Anna Lesley Hargreaves and Jenifer Penny (SSC members)

References: Recovery Strategy (Parks Canada 2013)

Assigned overall threat impact: C = Medium

Impact adjustment reasons: Adjusted, as many threats at the low end of their range. Some management of threats, that is, invasive plant species, occurs.

Overall threat comments: Annual plant with seed bank of unknown viability. Three generations could be 10 to 15 years or more (seeds of other Meadowfoam species kept in cold storage for 15 years). Whirl Bay subpopulation maintained by tilling and would not survive if this semi-annual practice was discontinued, so considered a managed subpopulation and not included in the threat impact assessment here.

Classification of Threats adopted from IUCN-CMP, Salafsky et al. (2008).