COSEWIC Assessment and Update Status Report on the Water-plantain Buttercup Ranunculus alismifolius in Canada - 2009

Table of Contents

List of Figures

List of Tables


Water-plantain Buttercup Ranunculus alismifolius

Photo of the Water-plantain Buttercup Ranunculus alismifolius.

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Endangered 2009

COSEWIC -- Committee on the Status of Endangered Wildlife in Canada

COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:

COSEWIC. 2009. COSEWIC assessment and update status report on the Water-plantain Buttercup Ranunculus alismifolius in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 21 pp.

Previous reports:

COSEWIC. 2000. COSEWIC assessment and status report on the Water-plantain Buttercup Ranunculus alismaefolius var. alismaefolius in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 17 pp.

Illingworth, J.M., and G.W. Douglas. 1996. COSEWIC status report on the Water-plantain Buttercup Ranunculus alismaefolius var. alismaefolius in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-17 pp.

COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:

COSEWIC. 2009. COSEWIC assessment and update status report on the Water-plantain Buttercup Ranunculus alismifolius in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 21 pp.

Production note:

COSEWIC acknowledges Matt Fairbarns for writing the update status report on Water-plantain Buttercup Ranunculus alismifolius in Canada, prepared under contract with Environment Canada, overseen and edited by Erich Haber, Co-chair, COSEWIC Vascular Plants Specialist Subcommittee

For additional copies contact:

COSEWIC Secretariat
c/o Canadian Wildlife Service
Environment Canada
Ottawa, ON
K1A 0H3
Tel.: 819-953-3215
Fax: 819-994-3684
COSEWIC E-mail

COSEWIC Web Site

Également disponible en français sous le titre évaluation et Rapport de situation du COSEPACsur la renoncule à feuilles d’alisme Ranunculus alismifolius au Canada -- Mise à jour.

Cover illustration: Water-plantain Buttercup - Photo by Jenifer Penny.

© Her Majesty the Queen in Right of Canada, 2009.
Catalogue No.CW69-14/582-2009E-PDF
ISBN978-1-100-12949-5

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COSEWIC Assessment Summary

Assessment Summary – April 2009

Common name: Water-plantain Buttercup
Scientific name: Ranunculus alismifolius
Status: Endangered
Reason for designation: This species has been reduced to two small populations within the highly impacted Garry Oak Ecosystem of southwestern British Columbia. Impacts from human activities and spread of invasive plants within and around its vernal pool habitats continue to place the species at risk of extirpation.
Occurrence: British Columbia
Status history: Designated Endangered in April 1996. Status re-examined and confirmed in May 2000 and in April 2009. Last assessment based on an update status report.

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COSEWIC Executive Summary

Water-plantain Buttercup Ranunculus alismifolius

Species information

Water-plantain Buttercup Ranunculus alismifolius is a perennial herb. It produces one to several erect stems from a common base. The leaves are at least twice as long as they are wide, broadest above the base and narrowed to the tip. The leaf margins are either entire or weakly toothed, but never deeply lobed. The flowers usually have five bright yellow petals, each 5-10 mm long. The species consists of several varieties but only var. alismifolius occurs in Canada.

Distribution

Water-plantain Buttercup occurs throughout much of western North America, from British Columbia south to California, east to Montana, Wyoming and Colorado.

In Canada, Water-plantain Buttercup is presently found at only two severely fragmented coastal locations, in southwest British Columbia. The extent of occurrence is estimated at approximately 500 km² and the index of area of occupancy is 8 km²when based on a 2x2 km grid.

Habitat

In Canada, Water-plantain Buttercup occurs in low elevation, coastal vernal pools associated with Garry Oak ecosystems. Summer temperatures are greatly moderated by proximity to the ocean. Coastal fogs and the proximity to shoreline tend to moderate winter frosts (particularly at night), retard the accumulation of heat and may slow down the development of plants, particularly in the late spring. Coastal vernal pools are free of woody vegetation because they are saturated for several months between November and April and experience strong summer moisture deficits.

The amount of potential habitat on southeast Vancouver Island and the adjacent offshore islands has declined greatly over the past century as vernal pools have been destroyed during the development of land for residential and recreational use. The sites supporting the two remaining Canadian populations of Water-plantain Buttercup are unlikely to be developed in the foreseeable future but there is a continuing decline in the extent of sites suitable for replacement populations to make up for those lost in the past.

The vernal pool sites where Water-plantain Buttercup now occurs have a significant component of invasive grasses and forbs and the small vernal pools are negatively influenced by shrub invasion into adjacent meadow habitats.

One of the extant populations occurs at the junction of several walking trails within a heavily-used municipal park. The habitat is greatly affected by soil compaction and occasionally damaged by dogs pawing the ground. The major trails are regularly mowed by municipal workers to create firebreaks, and mowing often occurs before the plants have set seed. Bicyclists have dug out soil in the vicinity of Water-plantain Buttercups (in one case directly damaging plants) in order to create ramps and jumps.

One of the extant populations lies within a municipal park managed by the Municipality of Oak Bay. The other population occurs on federal lands managed by the Department of National Defence. Much of the unoccupied vernal pool habitat that remains within the region of the two occurrences is in municipal parks.

Biology

Shoot dormancy begins to break in early March, when soil in the vernal pool begins to warm up. By late March, most shoots have broken dormancy. In typical years, the first floral buds can be detected by late April and flowering peaks in mid-May. Green fruits develop in May and early June and ripe, undehisced fruit are usually present by mid-June. By mid- to late June the soil has dried out, the shoots have begun to die back, and the seeds are shed. Most seeds of Water-plantain Buttercup are probably dispersed over short distances (< 10 m), floating in pooled water.

There is no asexual reproduction and the longevity of this perennial is unknown.

Population sizes and trends

Water-plantain Buttercup has been found in at least two, and perhaps as many as four locations in Canada but there are only two extant populations. Based on the most recent data from each site in 2007, there were 306 flowering plants in Canada. Over the past 10-15 years the Canadian population has fluctuated between about 45 and 306 mature, reproductive individuals per year.

Limiting factors and threats

At one site, Water-plantain Buttercups are regularly damaged by mowing and trampling. Grazing animals also remove flowers from many plants before they set seed. There are no major, immediate threats to Water-plantain Buttercups at the other site.

Special signifiance of the species

Water-plantain Buttercup is sometimes used to restore damaged wetland ecosystems within its USrange.

Existing protection or other status designations

Globally, Water-plantain Buttercup is ranked by NatureServe as secure from extinction. In British Columbia, it is critically imperilled. In 2000, COSEWIC ranked Water-plantain Buttercup as Endangered in Canada. The species is also listed as endangered on Schedule 1 of the federal Endangered Species Act. This provides protection only for the population on the Department of National Defence property at Ballenas.

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 (2009)

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

Data Deficient (DD)***
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.

* Formerly described as "Vulnerable" from 1990 to 1999, or "Rare" prior to 1990.
** Formerly described as "Not In Any Category", or "No Designation Required."
*** 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.

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

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Update - COSEWIC Status Report on the Water-plantain Buttercup Ranunculus alismifolius in Canada - 2009

Species Information

Name and classification

Scientific name:Ranunculus alismifolius Geyer ex Benth.
Common names: Water-plantain Buttercup; Plantainleaf Buttercup, Dwarf Buttercup
Family: Ranunculaceae, Buttercup family
Major Plant group: Eudicot flowering plant

Water-plantain Buttercup is a well-defined species. There are four (ITIS 2007) to six (Whittermore and Parfitt 1997) accepted varieties but only var. alismifolius occurs in Canada (NatureServe 2007). The original COSEWIC status report used the name Ranunculus alismaefolius var. alismaefolius (Illingworth and Douglas 1996) but the spelling of “alismaefolius” violates rules of Latin grammar.

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Morphological description

Water-plantain Buttercup (Figure 1) is a perennial herb growing up to 60 cm tall. It produces one to several erect stems from a common base, and the stems are not capable of rooting at the nodes. The upper portion of the stems are usually branched. The leaves are at least twice as long (to 14 cm) as they are wide, broadest above the base and narrowed to the tip. The leaf margins are either entire or weakly toothed, but never deeply lobed. The lower leaves are born on long narrow stalks; leaves on the middle of the stem are borne on shorter stalks, and leaves on the upper part of the stem are without stalks. Flowers have bright yellow petals, like those of most buttercups. There are usually 5 petals per flower, each 5-10 mm long, but some flowers may have up to 10 petals. There are 10-60 pistils (female reproductive organs) in the centre of a flower, each of which may form a smooth, hairless achene (a type of dry fruit containing a single seed). The achenes are 1.5-2.5 mm long and have a straight terminal “beak” about 1 mm long (Hitchcock et al. 1964).

Figure 1. Illustration of Water-plantain Buttercup. The main figure is a mature plant. The small feature on the lower left is an achene (fruit). Janish from Hitchcock et al. 1964 with permission.

Illustration of the Water-plantain Buttercup. The main figure is a mature plant. The small feature on the lower left is an achene (fruit).

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Lesser Spearwort (Ranunculus flammula) is the only other species within its Canadian range that might be confused with Water-plantain Buttercup. Lesser Spearwort has arching to trailing stems, which root at the nodes, and tends to have smaller, narrower leaves.

Sagebrush Buttercup (Ranunculus glaberrimus var. ellipticus) is superficially similar to Water-plantain Buttercup and may occasionally lack lobed leaves. Such specimens may be misidentified as R. alismifolius using some keys but can be distinguished from true R. alismifolius by virtue of their broader leaf blades and a single stem arising from the base. Sagebrush Buttercup does not occur west of the Coast-Cascade Mountains in Canada whereas Water-plantain Buttercup does not occur east of the Coast-Cascades.

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Genetic description

The chromosome numbers for Water-plantain Buttercup are unknown and it does not appear that any genetic studies have been conducted on the species.

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Designatable units

A single designatable unit is recognized based on the occurrence of a single variety in Canada that is geographically restricted to a small region of British Columbia within a single COSEWIC ecological area (Pacific).

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Distribution

Global range

Water-plantain Buttercup occurs throughout much of western North America from British Columbia south to Baja California, east to Montana, Wyoming and Colorado (Whittermore and Parfitt 1997). Variety alismifolius (Figure 2) occurs from B.C. to California and east to Idaho and Montana (Whittermore and Parfitt 1997).

Figure 2. Global distribution of Water-plantain Buttercup (var. alismifolius). Adapted from Kartesz and Meacham 1999, Hitchcock et al. 1964.

Map showing the global distribution of the Water-plantain Buttercup.

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Canadian range

In Canada, Water-plantain Buttercup is found at only two coastal locations, in southwest British Columbia (Figure 3). The two extant populations are approximately 120 km apart and other former populations reported from B.C. lie in-between. The extent of occurrence was estimated by calculating the approximate length (in km) of coastline between the two sites and along nearby islands, and multiplying that value by 1.0 (because the species is unlikely to grow more than 1 km inland). Using this procedure, the extent of occurrence is estimated at approximately 500 km². The actual area occupied is less than 500 , but the two populations occur in different 2 kmx 2 km cells, therefore the Index of Area of Occupancy is 8 km²according to the COSEWIC mapping convention or only 2 km² when based on a 1x1 km grid.

Figure 3. Locations (stars) of the two extant populations of Water-plantain Buttercup in Canada.

Map showing the locations of the two extant populations of the Water-plantain Buttercup in Canada.

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The populations are considered to be severely fragmented based on the following factors: there are only two populations extant in 2007 separated by a large distance (approximately 120 km) that precludes interchange of propagules; the populations are very small and occupy tiny areas of habitat (Oak Bay, 121 plants in 128 ; Ballenas, 185 plants in 32 ); and the long-term viability of such small populations at ongoing risk from several factors is highly questionable.

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Habitat

Habitat requirements

In Canada, Water-plantain Buttercup occurs in low elevation, coastal vernal pools associated with Garry Oak ecosystems. Summer temperatures are greatly moderated by proximity to the ocean. Coastal fogs and the proximity to shoreline tend to moderate winter frosts (particularly at night), retard the accumulation of heat and may slow down plant development, particularly in the late spring. Coastal vernal pools are free of woody vegetation because they are saturated for several months between November and April and experience strong summer moisture deficits (Fairbarns, pers. obs.).

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Habitat trends

Habitat loss

The amount of potential habitat on southeast Vancouver Island and the adjacent offshore islands has declined greatly over the past century as vernal pools have been destroyed during the development of land for residential and recreational use. There are no reliable estimates of the rate of loss of vernal pools but it probably exceeds the rate of loss of Garry Oak ecosystems in Victoria because the vernal pools were more concentrated along the desirable shoreline locations and provided more level building sites. The extent of Garry Oak ecosystems in Victoria decreased 95% from 10,510 ha in 1800 to 512 ha in 1997 (Lea 2002). The sites supporting the two remaining Canadian populations of Water-plantain Buttercup are unlikely to be developed in the foreseeable future but there is an ongoing decline in the extent of sites suitable for the establishment of new populations as recommended in the recovery strategy for this species (Parks Canada 2006). This is due to strong demands for more recreational sites and more intensive housing development within the Canadian range of Water-plantain Buttercup. For example, the population of metropolitan Victoria has increased from approximately 180,000 in 1966 to an estimated 348,467 in 2007 and is projected to increase to 407,600 by 2026 (CRD 2007a,b). The most expensive and sought-after properties are in coastal areas, where most Water-plantain Buttercup habitat is found. As a result, there will be continued pressure to develop vernal pool habitat capable of supporting the species.

Recreational trails

One of the populations of Water-plantain Buttercup is on a remote island where there is little recreational use. The other population occurs within a heavily-used municipal park. The major portion of this population occurs at the junction of a number of walking trails and the plants are regularly trampled by walkers and occasionally damaged by dogs. The major trails are regularly mowed by municipal workers to create firebreaks, and mowing sometimes occurs before the plants have set seed (Fairbarns, pers. obs.). The deleterious effects of mowing may, however, be offset by the benefits achieved by removing invasive grass biomass. Bicyclists have dug out soil in the vicinity of Water-plantain Buttercups (in one case directly damaging plants) in order to create ramps and jumps for unauthorized BMX courses (Fairbarns, pers. obs.). The municipal government has tried to discourage this illegal activity and has attempted to remediate damaged sites, but the bicyclists have not been apprehended and may continue their activities (Middleton, pers. comm. 2005).

Habitat invasion by exotic species

Water-plantain Buttercup is now restricted to vernal pools a few metres above sea level in coastal areas including offshore islands. These sites now have a significant component of invasive grasses and forbs. The most abundant of these are Creeping Buttercup (Ranunculus repens), Common Velvetgrass (Holcus lanatus), Orchard Grass (Dactylis glomerata) and Creeping Bentgrass (Agrostis stolonifera). The vernal pools where Water-plantain Buttercup grows are small and are influenced by shrub invasion on adjacent meadow habitats (Fairbarns, pers. obs.), particularly by Cut-leaved Blackberry (Rubus laciniatus) and European Hawthorn (Crataegus monogyna).

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Protection/ownership

One of the extant populations lies within a municipal park managed by the Municipality of Oak Bay. The municipality has established a program to control invasive species in the habitat of a number of species at risk on park lands, including the population of Water-plantain Buttercup. The municipal program began in 2005 but was preceded by volunteer efforts that are poorly documented. Invasive shrubs have been removed, primarily by mechanical means. The targeted shrub species have tended to re-invade the treated sites through recruitment from the soil seed bank and/or by dispersal from nearby areas (e.g., European Hawthorn has been planted as an ornamental tree along nearby roadsides and its berries are widely dispersed by birds). The municipality has not provided effective habitat protection from threats posed by recreational activities.

The other population occurs on federal lands managed by the Department of National Defence (DND). The population occurs on a remote site where public access is prohibited. Invasive species are not yet common at the site but their presence in the vicinity suggest that they pose a moderate future threat to habitat at this site. Steps have not yet been taken to control invasive plants.

Much of the unoccupied vernal pool habitat that remains within the extent of occurrence is in municipal parks, which lack formal policies to protect species at risk. Nevertheless, some of these municipalities have taken measures to protect vernal pool habitat by controlling invasive shrubs.

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Biology

General

There is very little published information on the biology of Water-plantain Buttercup. The following section, except where specified, is based on field observations of the Oak Bay population by Matt Fairbarns between 2002-2007.

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Life cycle and reproduction

Shoot dormancy begins to break in early March, when soil in the vernal pool begins to warm up, and is completed by the end of March. In average years, the first floral buds can be detected by late April and flowering peaks in mid-May. Green fruits develop in May and early June and ripe, undehisced fruit are usually present by mid-June. By mid- to late June the soil has dried out, the shoots have begun to die back, and the seeds are shed.

Germination trials have shown that optimum conditions are achieved by sowing seeds in a heated greenhouse for 2 months and then bringing them into cooler conditions for 2 weeks. Attempts to increase seed supplies by growing the plants in tubs failed and the plants have now been transplanted into field plots (Bartow 2007).

Van der Pijl (1982) reported that the achenes of Creeping Buttercup (Ranunculus repens) may be dispersed by wind, in animal dung, and on the fur and feathers of animals. The achene coat resists wetting, therefore surface tension may allow the achenes to float to new sites (Van der Pijl 1982). Most achenes of Water-plantain Buttercup likely disperse over short distances in pooled water.

At both Canadian sites, the plants are either low in stature or grow in relatively sheltered locations that limit the potential for wind-aided dispersal. In contrast to Creeping Buttercup, the achene beak of Water-plantain Buttercup is not hooked, therefore the achenes are less likely to disperse on the exterior of animals. Flowers are sometimes grazed but herbivores rarely feed on inflorescences bearing ripe seed. Small birds or waterfowl may occasionally consume ripe seed lying on the soil surface and carry them away to new locations within their gut or attached to their muddy feet. There appears to be considerable suitable habitat within 500 m of the Oak Bay population yet the plants have not spread more than 1-2 m between 1996 (when they were first mapped) and 2007. This suggests that dispersal over distances of > 10 m occurs rarely.

Water-plantain Buttercup does not reproduce asexually. Neither the average age nor the longevity of plants is known but plants may require several years after germination to flower.

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Herbivory

A significant proportion of plants may be grazed by vertebrates. Generally, the leaves are left intact and only the flowering inflorescences are removed (Fairbarns, pers. obs.) with fruiting inflorescences being left untouched. Insects rarely cause significant damage to the foliage.

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Interspecific interactions

Taller shrubs and trees presumably suppress growth by limiting the amount of light available to Water-plantain Buttercup. Woody and herbaceous species (particularly robust invasive grasses and forbs) compete for nutrients. No evidence of other, biologically significant interspecific interactions affecting Water-plantain Buttercup has been noted.

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Population Sizes and Trends

Search effort

Water-plantain Buttercup has attractive, showy flowers that are not easily overlooked. It has distinctive leaves that easily distinguish it from other plants with bright yellow flowers, including other species of buttercups. Suitable sites throughout the range of the species have been surveyed repeatedly since the early 1980s in a series of projects designed to document the distribution of rare plants of vernal pools and seeps on southeast Vancouver Island and the Gulf Islands. The survey effort has exceeded 300 person-days. The principal investigators included Adolf and Oldriska Ceska, Matt Fairbarns, Hans Roemer, Jenifer Penny, Harvey Janszen, Frank Lomer and the late George Douglas, all of whom are/were familiar with Water-plantain Buttercup. Fairbarns has conducted a focused search for Water-plantain Buttercup in vernal pools throughout the extent of occurrence of the species (Figure 4) since 2002. This involved visits (during the key flowering/fruiting period when the species is most obvious). The areas included the following:

  1. all accessible vernal pool complexes along the coast of southeastern Vancouver Island from which rare plant species have been reported
  2. all accessible vernal pool complexes along the shoreline of Vancouver Island from East Sooke to Swartz Bay (the area with the greatest concentration of rare vernal pool species), and
  3. all vernal pool complexes on islets and islands offshore of Vancouver Island from East Sooke to Swartz Bay.

No new populations were discovered by Fairbarns during these surveys.

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Figure 4. Distribution of search effort by Fairbarns (2002-2006) in habitat suitable for Water-plantain Buttercup.

Map showing the distribution of search effort by Fairbarns between 2002 and 2006

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Abundance

In the absence of species-specific information on rates of genetic exchange, occurrences of Water-plantain Buttercup more than 1,000 m apart are treated as separate locations. On this basis, it has been reported from at least two, and perhaps as many as four locations in Canada (Table 1), only two of which have extant populations. Two populations (Oak Bay 1 and Oak Bay 2) are reported based on old herbarium specimens with labels that lack precise locations. Oak Bay 1 may be synonymous with Oak Bay 2 or 3 or may have been a distinct population. Oak Bay 2 was probably a separate (now extirpated) population; the herbarium label notes that the plants were collected from “Cadboro Bay Road”, which now runs through a developed residential neighbourhood. Illingworth and Douglas (1996) suggested that Oak Bay 2 might be synonymous with Oak Bay 3 population but this seems unlikely because most of Cadboro Bay Road is more than 1 kmdistant from Oak Bay 3 (even the nearest point along Cadboro Bay Road is more than 700 m away from Oak Bay 3). Oak Bay population 3 consists of two subpopulations (i.e., patches separated by <1,000 m), which are denoted as 3a and 3b in Table 1. Oak Bay subpopulations 3a and 3b are approximately 250 m apart. The Ballenas population consists of two small patches less than 20 m apart. Based on the most recent data from each site, there were 306 flowering plants in Canada. Although flowers are sometimes consumed by herbivores, most plants appear to produce at least some flowers that survive to produce seed.

Table 1. Localities, population and land ownership for Water-plantain Buttercup
LocationYearCollector/ObserverNumber of Plants/areaLand ownership/Notes
Oak Bay 11887MacounUnknownUnknown
Oak Bay 21900AndersonUnknownUnknown
Oak Bay 3an.d.BrayshawUnknownMunicipal park
1991Douglas17/ ?
1994Douglas32/4
1997Douglas and Penny15/2
2002Penny12/1
2006Fairbarns55/1
Oak Bay 3b1987BrayshawUnknownMunicipal Park
1991Douglas40/?
1994Douglas18/1
1997Douglas and Penny46/7
2002Penny46/12
2006Fairbarns66/100
Ballenas1995Ceska15-20/5-10 Department of National Defence
1998DouglasUnknown
2005Fairbarns112/16
2007Fairbarns185/16

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Fluctuations and trends

The number of mature, reproductive Water-plantain Buttercup plants in a given population fluctuates, probably as a result of among-year variations in soil moisture during the spring and early summer as well as other less significant factors such as flower and seed predation. Subpopulation 3a has fluctuated from 12-55 flowering individuals over as few as four years. A similar magnitude of fluctuation was observed in subpopulation 3b, which varied from 18-66 individuals over a 12-year period. Surprisingly, fluctuations at subpopulations 3a and 3b were far from synchronous; subpopulation 3b did poorly in 1994 even though subpulation 3a did rather well that year. There does not seem to be any clear trend in population size in either subpopulation or in Oak Bay population 3 as a whole. The Ballenas population fluctuates between 15 and 185. Overall, the Canadian population appears to be fluctuating between about 45 and 306 mature, reproductive individuals per year.

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Rescue effect

Extensive floristic surveys have been conducted in nearby areas of Washington State, including the Olympic Peninsula (Buckingham et al. 1995), the main islands of San Juan County (Atkinson and Sharpe 1993) and small islets in San Juan County (Giblin, pers. comm. 2006). From these studies, it appears that Water-plantain Buttercup is absent from the Olympic Peninsula and the San Juan Islands and the nearest U.S. populations are at least 50 km from Canada. For these reasons, there is negligible opportunity for unassisted genetic immigration (seed or pollen) from the United States.

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Limiting Factors and Threats

Mowing and trampling, which are discussed under Habitat trends, pose a direct threat to the plants as well as invasion of the pools by exotic species, especially grasses and flowering herbs.

Herbivory poses a threat to population processes, because inflorescences are removed before mature seeds are produced.

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Special Significance of the Species

Water-plantain Buttercup has potential as an ornamental for water gardens. It has been incorporated into a seed mix used to restore wet prairies in the Willamette Valley of western Oregon (City of Eugene 2007). The material is being provided by the United States Department of Agriculture National Resource Conservation Service, which has conducted germination trials and grown plants out as container stock at their Corvallis Plant Materials Center (Bartow 2007).

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Existing Protection or Other Status Designations

The Nature Conservancy of the US has ranked Water-plantain Buttercup (var. alismifolius) as “G5T5” (globally secure and essentially ineradicable). It has not been ranked by NatureServe member programs in California, Washington, Idaho, Oregon, Montana, Nevada, and Wyoming, which generally means it is present but secure (NatureServe Explorer 2007).

The British Columbia Ministry of Environment has included Water-plantain Buttercup in the "Red-list" of taxa that are threatened or endangered in British Columbia and has ranked it as "S1" (critically imperilled) in British Columbia (BC Species and Ecosystems Explorer 2007). Such a designation does not, however, confer protection of the species in the province. COSEWIC ranked Water-plantain Buttercup as Endangered in Canada (2000). The species is also listed as endangered on Schedule 1 of the federal Species at Risk Act. This only provides protection on federal lands such as at the Department of National Defence property at Ballenas.

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Technical Summary

Ranunculus alismifolius

Water-plantain Buttercup Renoncule à feuilles d’alisme

Range of Occurrence in Canada: British Columbia

Demographic Information

Generation time (average age of parents in the population): Unknown; at least several years just to flowering stage
[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over the last [10 or 5 years, or 3 or 2 generations]: n/a
[Projected or suspected] percent [reduction or
increase] in total number of mature individuals
over the next [10 or 5 years, or 3 or 2 generations]:
n/a
[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over any [10 or 5 years, or 3 or 2
generations] period, over a time period including both
the past and the future:
n/a
Are the causes of the decline clearly reversible? n/a
Are the causes of the decline understood? n/a
Have the causes of the decline ceased? n/a
[Observed, inferred, or projected] trend in number of populations:Stable
Are there extreme fluctuations in number of mature individuals? No but fluctuation does occur
Are there extreme fluctuations in number of populations? No

Extent and Area Information

Estimated extent of occurrence: 500 km²
[Observed, inferred, or projected] trend in extent of occurrence:Stable over past 10 years
Are there extreme fluctuations in extent of occurrence? no
Index of area of occupancy (IAO) 8 km² based on 2x2 km grid
2 km² based on 1x1 km grid
[Observed, inferred, or projected] trend in area of occupancy:Stable
Are there extreme fluctuations in area of occupancy? no
Is the total population severely fragmented? yes
Number of current locations: 2
Trend in number of locations: Stable
Are there extreme fluctuations in number of locations? no
Trend in [area and/or quality] of habitat: Decline in quality

Number of mature individuals in each population

Population N Mature Individuals
Oak Bay (fluctuates 30-121): 121 (2006)
Ballenas (fluctuates 15-185): 185 (2006)
Total (variable due to fluctuation): ~45-306
Number of populations (locations): 2

Quantitative Analysis

None available

Threats (actual or imminent, to populations or habitats)

Threats to habitat: habitat loss, invasive species, recreational trail use
Threats to populations: mowing, herbivory, trampling

Rescue Effect (immigration from an outside source)

Status of outside population(s)? USA: secure
Is immigration known? no
Would immigrants be adapted to survive in Canada? unknown
Is there sufficient habitat for immigrants in Canada? yes
Is rescue from outside populations likely? no

Current Status

COSEWIC:Endangered (2009)
Additional Sources of Information: none

Status and Reasons for Designation

Status: Endangered
Alpha–numeric code:B1ab(iii)+2ab(iii); C2a(i)

Reasons for designation:
This species has been reduced to two small populations within the highly impacted Garry Oak Ecosystem of southwestern British Columbia. Impacts from human activities and spread of invasive plants within and around its vernal pool habitats continue to place the species at risk of extirpation.

Applicability of Criteria

Criterion A (Decline in Total Number of Mature Individuals):
No data available to demonstrate decline of sufficient magnitude to meet criterion.

Criterion B (Small Distribution Range and Decline or Fluctuation):
Meets Endangered B1ab(iii)+2ab(iii) with EO and IAO below critical levels and the quality of the habitat at the two extant populations continues to decline.

Criterion C (Small and Declining Number of Mature Individuals):
Meets Endangered C2a(i) with total population <2500 plants and no population > 250 individuals with a continuing decline in population inferred due to impacts from mowing, herbivory, and trampling, especially in the highly urbanized area of the Oak Bay population.

Criterion D (Very Small Population or Restricted Distribution):
Meets Threatened D1 with < 1000 individuals and Threatened D2 with only 2 localities and ongoing threats.

Criterion E (Quantitative Analysis):
None available.

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Acknowledgements and Authorities Consulted

The author would like to acknowledge the generous help, in the field and in conversation, provided by Mike Miller and Jenifer Penny. The author also received valuable support from the Canadian Forest Service and the Department of National Defence.

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Information Sources

Authorities consulted

  • Dr. Patrick Nantel. Conservation Biologist, Species at Risk Program. Parks Canada.
  • David Fraser. Endangered Species Specialist. Biodiversity Branch, Conservation Planning Section, Ministry of Environment, Government of British Columbia.
  • Gloria Goulet. Coordinator, Aboriginal Traditional Knowledge. COSEWIC Secretariat, Canadian Wildlife Service, Environment Canada.
  • Kevin Fort. Species at Risk Biologist. Pacific Wildlife Research Centre, Canadian Wildlife Service, Environment Canada.
  • Jenifer Penny. Botanist. British Columbia Conservation Data Centre. Victoria, British Columbia.

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Literature cited

Atkinson, S. and F. Sharpe. 1993. Wild Plants of the San Juan Islands (2nd edition). The Mountaineers, Seattle. 191 pp.

Bartow, A. 2007. The 2006 Bureau of Land Management Annual Report: West Eugene Wetlands. Corvallis Plant Materials Center, Natural Resources Conservation Service. Corvallis, Oregon.

BC Species and Ecosystems Explorer. 2007. Victoria, British Columbia, Canada.

Buckingham, N.M., E.G. Schreiner, T.N. Kaye, J.E. Burger, and E.L. Tisch. 1995. Flora of the Olympic Peninsula. Northwest Interpretive Association. Seattle. 199 pp.

City of Eugene. 2007. West Eugene Wetlands Project.

CRD 2007a. Interim estimates of population growth.

CRD 2007b. Population forecasts, 2026.

Giblin, D. Pers. comm. 2006. E-mail correspondence with M. Fairbarns. Aug. 9, 2006. Collections Manager, University of Washington.

Hitchcock, C.L., A. Cronquist, M. Ownbey, and J.W. Thomson. 1964. Vascular plants of the Pacific Northwest. Part 2: Salicaceae to Saxifragaceae. Univ. Wash. Press, Seattle. 597 pp.

Illingworth, J.M. and G.W. Douglas. 1996. COSEWIC assessment and status report on waterplantain buttercup Ranunculus alismaefolius var. alismaefolius in Canada, in COSEWIC assessment and status report on water-plantain buttercup Ranunculus alismaefolius var. alismaefolius in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 15 pp.

ITIS 2007. Integrated Taxonomic Information System.

Kartesz, J.T. and C.A. Meacham. 1999. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, NC. ISBN 1-889065-05-6 [CD-ROM].

Lea, T. 2002. Historical Garry Oak Ecosystems of Greater Victoria and Saanich Peninsula. 1:20,000 Map. Terrestrial Information Branch, B.C.Ministry of Sustainable Resource Management. Victoria, B.C.

Middleton, L. Pers. comm. 2005. Conversations with M. Fairbarns. March, 2005. Manager, Parks Services, Municipality of Oak Bay.

NatureServe. 2007. An online encyclopedia of life. Version 6.2. NatureServe, Arlington, Virginia.

Parks Canada Agency. 2006. Recovery Strategy for Multi-species at Risk in Vernal Pools and Other Ephemeral Wet Areas in Garry Oak and Associated Ecosystems in Canada. In Species at Risk Act Recovery Strategy Series. Ottawa: Parks Canada Agency. 73 pp.

Pijl, van der L, 1982. Principles of dispersal in higher plants. 3rd edition. Springer-Verlag, Heidelberg.

Whittermore, A.F. and B.D. Parfitt. 1997. Ranunculaceae. In: Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 12+ vols. New York and Oxford. Vol. 3, pp.356-357.

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Biographical Summary of Report Writer

Matt Fairbarns has a B.Sc. in Botany from the University of Guelph (1980). He has worked on rare species and ecosystem mapping, inventory and conservation in western Canada for approximately 20 years. He was a botanist with the British Columbia provincial government until 2003 and now manages Aruncus Consulting, an independent biological conservation research company.

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Collections Examined

The following collections were examined:

  • Royal BC Museum herbarium (V)
  • University of Victoria herbarium (UVIC)