COSEWIC Assessment and Update Status Report on the Scouler’s Corydalis in Canada
Table of Contents
Assessment and Update Status Report
Not at risk
Committee on the Status
of Endangered Wildlife
Comité sur la situation
des espèces en péril
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 2006. COSEWIC assessment and update status report on the Scouler’s corydalis Corydalis scouleri in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 24 pp.
(Species at Risk Status Reports)
COSEWIC 2001. COSEWIC assessment and status report on the Scouler’s corydalis Corydalis scouleri in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 15 pp.
Douglas, G.W. and J.A. Jamison. 2001. COSEWIC status report on the Scouler’s corydalis Corydalis scouleri in COSEWIC assessment and status report on the Scouler’s corydalis Corydalis scouleri in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-15 pp.
COSEWIC ackowledges Brenda Costanzo, Jeff Hoyt and David F. Fraser for writing the update status report on the Scouler's corydalis Corydalis scouleri in Canada, and gratefully acknowledges George W. Douglas and Shyanne J. Smith who wrote the original status report.
COSEWIC also gratefully acknowledges the financial support of the Ministry of Environment, Lands and Parks, British Columbia. The COSEWIC review and editing of the update report was overseen by Erich Haber, Co-chair (Vascular plants), COSEWIC Plants and Lichens Species Specialist Subcommittee, with input from members of COSEWIC. That review may have resulted in changes and additions to the initial version of the update report.
For additional copies contact:
c/o Canadian Wildlife Service
Également disponible en français sous le titre Évaluation et Rapport de situation du COSEPAC sur la corydale de Scouler (Corydalis scouleri) au Canada - Mise à jour.
Scouler's Corydalis -- Line drawing by Jane Lee Ling in Douglas et al. (1998a).
© Her Majesty the Queen in Right of Canada 2007
Catalogue No.: CW69-14/62-2006E-PDF
Assessment Summary – November 2006
Not at Risk
Reason for designation:
A conspicuous perennial herb of riverside habitats that is restricted to a small region of south-western Vancouver Island. The species was previously assessed as threatened but is now known to be present at additional locations and is much more abundant than previously documented. There is no evidence of population decline or fluctuation and no significant threats appear to affect the species. More than one-half of the population is now in protected areas specifically managed for this species and, since extensive areas of suitable habitat remain to be surveyed, additional populations will likely be discovered.
Designated Threatened in May 2001. Status re-examined and designated Not at Risk in November 2006. Last assessment based on an update status report.
Scouler’s corydalis is a tall perennial herb with thick rhizomes. Stems are hollow, simple or somewhat branched above and 40–120 cm tall. The blue-green, glaucous (white to blue waxy powder) leaves are usually three in number, from near or above the middle of the stem. The lower one is often 20–30 cm long. The terminal inflorescence, appearing in May and June, is usually a compound raceme (an elongated inflorescence with youngest flowers at the tip) of 15–20, spurred, rosy-pink flowers.
Scouler’s corydalis occurs west of the Cascades Mountains (mostly coastal) from north-western Oregon northward through Washington’s Olympic Peninsula to south-western Vancouver Island. In Canada, C. scouleriis found only in south-western British Columbia. Sites are limited to the Carmanah Creek (new since the 2000 status report), Cowichan Lake, Klanawa River and Nitinat River drainages. The Canadian populations are located about 80 km north of the Washington populations of the Olympic Peninsula. Since 2000, the extent of occurrence has increased from 250 km2to 275 km2 due to additional search effort. However, due to limited road access to potential habitat for this species, a significant area of potential habitat remains unsearched at this time. The estimated further potential extent of Scouler’s occurrence is an additional 825 km2 if potential habitat in the Walbran and Cowichan Lake drainages is considered.
Lush stands of Scouler’s corydalis are found in wet, cool habitats associated with watercourses – ranging from large rivers to small tributary streams. Elevations range from sea level to almost 200 m on southwestern Vancouver Island, British Columbia. The species occurs on gradually sloping alluvial floodplains and river terraces within early seral mixed or deciduous forest habitat and rarely in coniferous stands. Of the Alnus rubra stands surveyed in the Nitinat River Valley of approximately 30 years old and older, all were found to contain C. scouleri. Scattered individuals are also found on road edges, ditches, clearings and other human-modified habitats.
Scouler’s corydalis is a perennial herb producing annual stems apically from thick rhizomes. Seedlings have a rather thick taproot, which probably remains at least until the plant reaches flowering age, and very likely much longer. Older specimens have only annual adventitious roots that originate in the spring just below the aerial part of the shoot.
Population Sizes and Trends
There are presently 24 known populations where Scouler’s corydalis has been observed in British Columbia within the last six years (1997 to 2004). Since 2000, new inventory has increased the number of known stems from 117 395 to 848 000 stems. Due to the nature of the growth habit of this species, it is not known how many stems make up an individual. For individual populations, stem numbers range from one up to 462 000. Seven of the populations have stem numbers over 20 000, which represent over 95% of all the stems in British Columbia. The extent of stems at the sites varies greatly in size from just a few square metres to 3.4 ha. Eight of the populations are over 0.5 ha in size. The total area currently occupied by these populations is 0.10 km2.
Limiting Factors and Threats
Current potential threats to Scouler’s corydalis, from logging, road and bridge building, recreational use and natural flooding are probably minor. These threats will have less impact on the total populations of Scouler’s corydalis since there are now known to be over 800 000 stems over a 275 km2 area. As well, Wildlife Habitat Areas prohibit logging, road and bridge building within the designated wildlife areas which protect over 400 000 stems. Road building and bridges have damaged some Scouler’s corydalis populations in the past; however, the total percentage of the population removed has been low (less than 2%). Some riverbank damage occurs when recreationalists have easy access to the rivers, but this is very minor at this time. Natural flooding, from time to time, removes riverbanks and floodplain populations resulting in only temporary population reduction because the flooding creates new habitat and could possibly provide a dispersal mechanism.
Special Significance of the Species
Scouler’s corydalis, along with a number of other Corydalis species, is well known in the horticultural trade. In addition, the alkaloidal properties of a large number of members of both the Fumariaceae and the closely related Papaveraceae (poppy family) are of great interest to plant taxonomists, plant chemists, and agronomists.
Existing Protection or Other Status
Scouler’s corydalis could be a candidate for protection in British Columbia under the provincial Wildlife Amendment Act 2004 as it is currently blue-listed by the provincial Conservation Data Centre and on the federal Species at Risk Act Schedule 1. The species was assessed as Threatened by COSEWIC in 2001. Three of the Scouler’s corydalispopulations in British Columbia are protected by the Provincial Park Act since they occur in two Provincial Parks and an Ecological Reserve covered by the Ecological Reserves Act. The Forest and Range Practices Act (FRPA) of British Columbia identifies conservation and management issues, including Wildlife Habitat Areas. Scouler’s corydalis is presently listed under the Identified Wildlife Management Strategy under the Government Actions Regulation of FRPA. Wildlife Habitat Areas have been officially designated under the British Columbia Forest and Range Practices Act for eight of the populations in the Nitinat River drainage. This includes sites with approximately 437 100 stems protected through this means. These Wildlife Habitat Areas are to be managed for Scouler’s corydalis. Although not stated in the original status report, populations of the species occur within a Provincial Park (44 850 stems) and an Ecological Reserve (less than 15 stems).
Under the Forest and Range Practices Act, larger fish-bearing streams such as the Nitinat, Klanawa and Carmanah-Walbran are managed under a default standard that requires a Riparian Reserve zone associated with a Management zone. As such, licensees can be encouraged to leave the management zones intact and associate their wildlife tree retention to help protect and buffer potential habitat for Scouler’s corydalis within these areas.
In addition, both Western Forest Products and Teal Jones have recorded the British Columbia Conservation Data Centre information for Scouler’s corydalis in their GIS systems and have referred to the data for tree harvest planning.
COSEWIC History, Mandate, Membership and Definitions
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.
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 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.
- 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.
The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.
Lists of Figures and Tables
List of Figures
- Figure 1: Illustration of Scouler’s Corydalis
- Figure 2: Scouler’s Corydalis Habitat in the Nitinat River Drainage
- Figure 3: North American Range of Scouler’s Corydalis
- Figure 4: Scouler’s Corydalis Sites in British Columbia
- Figure 5: Protected Areas for Scouler’s Corydalis in the Nitinat River Drainage Area
- Figure 6: Protected Areas for Scouler’s Corydalisin Klanawa River and Carmanah Creek
List of Tables
- Table 1: Protected Areas Summary Table – Area and Number of Stems
- Table 2: Population Sizes for Scouler’s Corydalis in British Columbia
COSEWIC Status Report
Scouler’s corydalis is a tall perennial herb with thick rhizomes (Douglas et al. 1999a, Douglas and Jamison 2000). Stems are hollow, simple or somewhat branched above and 40–120 cm tall. The blue-green, glaucous (white or blue waxy surface) leaves are usually three in number, from near or above the middle of the stem. The lower one is often 20–30 cm long (Figure 1). The terminal inflorescence, appearing in May and June, is usually a compound raceme (an elongated inflorescence with youngest flowers at the tip) of 15–20, spurred, rosy-pink flowers. For each plant, the large dissected leaves form a delicate blue-green canopy, which intermingles in dense stands with other canopies to form a raised carpet of lush foliage about 1 m above the forest floor (Figure 2). There is no comprehensive monograph for this genus, although about 110 species of Corydalis are known to exist, native to the North Temperate zone and South Africa (Liden 1986).
From Douglas et al. 1999a, with permission.
Douglas Ecological Consultants 2003
Flowers of Scouler’s corydalis are bilaterally symmetrical, with two laterally placed outer petals, one of which is spurred or hooded, and two inner, dorsiventrally placed petals opposite the rudimentary and quickly deciduous sepals. The tips of the inner petals join to form a second hood that shelters the single, two-lobed stigma and the six stamens fused in two groups alternating with the petals. The obovoid, bicarpellate capsule separates elastically when jarred only slightly, to scatter the shiny, black seeds one to two metres away. As with most other species of corydalis, Scouler’s corydalis has elaiosomes on its seeds. These are fatty bodies that encourage dispersal by ants.
There has been no known genetic research on Canadian Scouler’s corydalis populations.
Scouler’s corydalis is restricted to the Pacific Northwest in North America. It occurs west of the Cascades Mountains (mostly coastal) from north-western Oregon northward through Washington’s Olympic Peninsula to south-western Vancouver Island (Figure 3; Ownbey 1947; Hitchcock et al. 1969; Douglas et al. 1999a, 2000).
In Canada, Scouler’s corydalis is found only in south-western British Columbia. Known sites are limited to the Carmanah Creek, Cowichan Lake, Klanawa River and Nitinat River drainages (Figure 4; Douglas et al. 1999a). The extent of Scouler’s corydalis occurrence in Canada encompasses approximately 275 km2. However, due to limited road access to potential habitat for this species, a significant area of potential habitat remains unsearched at this time. The estimated further potential extent of Scouler’s corydalis occurrence is an additional 825 km2 if potential habitat in the Walbran and Cowichan Lake drainages is considered.
Refer to Table 2 for population sizes within each of the drainage areas).
The south-western British Columbia occurrence of Scouler’s corydalis is about 80 km north of the Washington locations on the Olympic Peninsula. The Canadian range currently makes up approximately nine percent of the species’ total North American range.
Lush stands of Scouler’s corydalis are found in wet, cool habitats associated with watercourses – ranging from large rivers to small tributary streams. Elevations range from sea level to approximately 200 m in British Columbia (Douglas and Jamison 2000). In British Columbia, this species is found in the CWHvm1 (submontane very wet maritime) variant of the Coastal Western Hemlock Biogeoclimatic Zone (Pojar et al. 1991). In regions where Scouler’s corydalis is locally abundant, such as lower elevations of Washington State’s Mt. Rainier National Park (Brockman, 1947) and the Nitinat River and Klanawa River drainages, the species occurs on gradually sloping alluvial floodplains and river terraces with slopes typically between 0-10%, although sometimes up to 40% (Douglas and Smith 2003). Larger and healthier populations were found on gently sloping or relatively flat sites. When not found on these flat flood plains, the aspect of sites was typically NW to NE, although one site had a SSW aspect. The substrate was typically composed of fine loam or silty-clay to sandy or gravelly sediments, sometimes along with larger gravels and cobbles. In the Nitinat Valley, this species is an understory component of the early seral mixed or deciduous forest habitat. All the red alder (Alnus rubra) stands of approximately 30 years and older surveyed in the Nitinat, were found to contain Scouler’s corydalis. In addition to red alder, other associated overstory tree species include Acer macrophyllum and Picea sitchensis, and with lesser frequency, Tsuga heterophylla and Thuja plicata. Prominent understory species include Polystichum munitum, Oplopanax horridus, Sambucus racemosa, Petasites frigidus var. palmatus, Ribes bracteosum, and Rubus spectabilis.
Scouler’s corydalisalso grows in roadside gravel banks and ditches. These sites, when sufficiently moist during the growing season, mimic the gravelly, natural habitats of the floodplains. Only one population of this type (with at least 500 stems) was sampled.
Habitat trends for Scouler’s corydalis are largely unknown; however, the species has been seen to colonize disturbed habitats, which reflects the species’ adaptable nature. The largest stands (over 400 000 stems or almost one-half of the total known stems) of Scouler’s corydalis in Canada have now been protected within Wildlife Habitat Areas under the provincial Forest and Range Protection Act. These areas are to be managed primarily for Scouler’s corydalis to protect it from forestry management activities.
There has likely been a very minor loss of habitat over the last 50 years to road and bridge construction in the Nitinat River drainage, although this is not likely to have significantly affected the amount of habitat available. There is substantial additional potential habitat that has not been surveyed due to inaccessibility (Figure 4). Because Scouler’s corydalis occurs in early seral forests developing on floodplains, suitable sites are likely continually in a process of gradual change, with new sites becoming available and older, established sites declining in suitability.
Direct human disturbance to the alluvial floodplain habitat has been minimal despite logging activity throughout the Nitinat valley. No sites have been affected by recent forestry practices, partly because of protection of riparian areas under the provincial Forest and Range Practices Act and the lack of commercially available species at these sites. However, one population (#23, Nitinat River drainage, see Figure 4) was degraded due to heavy equipment work during creek restoration, with only 6 stems remaining in 2003, from 30 stems in 1997. This small population may recover in the future because ample gravels are still exposed.
Almost all the large Scouler’s corydalis populations on south-western Vancouver Island have some type of protection. Although not stated in the original status report, populations of the species were known to occur in one Provincial Park (44 850 stems) and an Ecological Reserve (less than 15 stems). Another population of approximately 7 stems was recently discovered in a second Provincial Park (Carmanah-Walbran), although a thorough inventory has not been done of this area (see Table 1; Figures 5 and 6). These are therefore protected by provincial parks legislation from the threat of forest management activities.
|WHA or Protected|
Total size (ha)
|2 (part)||Upper Nitinat River-1-190||8||3||11||7 500|
|3 (part)||Jasper Creek-1-191||16||5||21||293 500|
|13 (part)||Mid Nitinat River-1-192||1||1||2||94 800|
|21||Lower Nitinat river-1-193||4||1||5||1 500|
|5||Upper Granite Creek-1-194||1||2||3||18 000|
|5||Lower Granite Creek-1-195||1||2||3||200|
|10||Klanawa Creek-1-196||4||5||9||11 600|
|6||Vernon Creek-1-197||15||10||25||10 000|
|4 (part)||Nitinat River Prov. Park||N/A||N/A||N/A||44 850|
|15||Klanawa Ecological Reserve||N/A||N/A||N/A||<15|
|No #||Carmanah-Walbran Prov. Park||N/A||N/A||N/A||7|
EO = “Element Occurrence” is an area of land and/or water in which a species or natural community is present. A principal EO may be a single contiguous area or may be composed of discrete patches or subpopulations. (NatureServe, 2006a).
WHA = Wildlife Habitat Area
Under the Forest and Range Practices Act (FRPA), larger fish-bearing streams such as the Nitinat, Klanawa and Carmanah-Walbran where Scouler’s corydalis is found are managed under a default standard that requires a riparian reserve zone associated with a management zone. The reserve zone is legislated and is to remain intact to ensure that characteristics necessary to keep the stream properly functioning and to also manage for wildlife. Therefore, licensees can be encouraged to leave the management zones intact and associate their wildlife tree retention to help protect and buffer potential Scouler’s corydalis habitat within these areas.
In May of 2006, the province established, under the FRPA, eight Wildlife Habitat Areas (WHAs) for significant populations (over 400 000 stems) of Scouler’s corydalis. These areas included the range of the species in the Nitinat and Klanawa Rivers (see Table 1 and Figures 5 and 6). Under this Act, the forestry companies are legally compelled to protect these populations from forest management activities. WHAs provide a similar level of protection for the species as the provincial Parks Act with regard to forestry management activities, which are the main threat to this species. Such activities are not permitted within WHAs or parks.
Those sites indicated by an asterisk and numbered 1-190 to 1-195 and 1-197 occur within Wildlife Habitat Areas designated for the protection of the species.
Site 1-196 occurs within a Wildlife Habitat Area designated for the protection of the species.
The majority of the current locations of Scouler’s corydalis occur on Crown Land within Tree Farm Licence (TFL) #44. This licence is presently held by Western Products (formerly Weyerhaeuser Canada). A second Tree Farm Licence (# 46) is now held by Teal-Jones Group (originally held by TimberWest until January 2004); this currently has three sites (#7, #8 & #9, Nitinat River drainage; see Figure 4). All of the Scouler’s corydalis populations that could be impacted by forestry operations have been identified and appear on forest management plans (Bill Beese, pers. comm.; Bo Ferguson, pers. comm.).
A portion of the largest site (#14, Nitinat River drainage; see Figure 4) occurs on the Ditidaht Band’s Chuchummisapo Reserve. There is no known threat to this population. At the time of the field survey by Douglas and Smith in 2003, Douglas recognized that they were near the edge of the Indian Reserve based on topographic maps but did not think that they were within its boundary (S. Smith, pers. comm. 2006). The Ditidaht Band has participated in the recovery team and is aware of the occurrence of the population.
Scouler’s corydalis is a long-lived perennial, rhizomatous herb. Little is known of the species’ biology, specifically its longevity, methods of long-distance terrestrial dispersal, and interspecific interactions.
Scouler’s corydalis reproduces asexually to form large clones, as well as sexually, with each flower in the raceme of 15–20 flowers having two carpels containing many seeds. Seeds are short-lived and desiccate quickly (Hartwell and Paige 2004).
Scouler’s corydalis begins flowering after four or more years of age. Flowering takes place in May and June in the Nitinat River watershed, and the plant becomes dormant by late summer. Both anthers and stigma are enclosed by the determinately shaped and arranged petals of Scoulers. Liden (1986) reports that most of the species in the tribe Corydaleae (to which Scouler’s corydalis belongs) are strongly self-sterile; Ryberg (1960) speculated that Scouler’s corydalis is very likely self-sterile, since the cultivated specimens from which he obtained ripe seeds did not produce fruits until individuals from two different clones were planted together. However, it is known that sometimes only the terminal flower of the raceme develops (Hitchcock et al., 1969), and this would severely compromise seed production. The species reproduces very well asexually by underground rhizomes and it is capable of sexual reproduction by seed.
Scouler’s corydalis produces annual stems apically from thick rhizomes that may also form horizontal stolons in older plants (see Ryberg 1960 for further details).
A number of pollinators visit Scouler’s corydalis, indicating that cross-fertilization probably occurs; however, recalling that few flowers develop, this may well not be an effective means of reproduction for the species.
Little is known about herbivory or grazing on Scouler’s corydalis. However, clipped stems, most likely the result of grazing by elk or deer, were observed occasionally during site visits by the authors in 2003. The presence of alkaloids in Scouler’s corydalis may reduce herbivory (Ownbey 1947). Few Corydalis species are eaten by deer, even in cultivated gardens where deer herbivory is high (D. Fraser pers. obs. 2006).
The range of climatic conditions that Scouler’s corydalis can withstand is unknown. The successful method of asexual reproduction employed by Scouler’s corydalis may explain the species’ ability to dominate large areas of shady floodplains. The species appears to be highly shade tolerant and does not seem to have specific edaphic requirements. It thrives in cultivation without specific treatment other than moisture and shade; however, limiting factors in the wild may constrain habitat suitability.
Periodic flooding may facilitate seed or rhizome dispersal, and may play a critical role in dispersal, as evidenced by the appearance of clustered subpopulations along streams and rivers. In addition, the obovoid, bicarpellate seed capsules separate elastically when jarred even slightly, which can scatter seeds up to two metres.
Ants are likely a viable short-range dispersal agent for seed of Scouler’s corydalis. The seeds of Corydalis species, including Scouler’s corydalis, have appendages called elaiosomes that contain lipids, proteins, sugar, and vitamins, a valuable nutritional source for ants. Although there is no known research on Scouler’s corydalis dispersal, Ohkawara et al. (1997) report dispersal of seeds by ants for C. ambigua , and Hanzawa et al. (1985) report this for C. aurea as well. Ohkawara et al. (1997) found that the mean dispersal distance of Corydalis ambigua seeds by ants was up to about 80 cm. Hanzawa et al. (1988) demonstated that dispersal by ants of Corydalis aurea seeds can increase population growth rate. In an earlier paper, Hanzawa et al. (1985) reported that the elaiosomes on the seeds of Corydalis aurea are attractive to ants, but repulsive to the deer mouse(Peromyscus maniculatus ), a seed predator. This mouse is also found on Vancouver Island.
Interspecific interactions other than pollinators and dispersers for Scouler’s corydalis are unknown.
Scouler’s corydalis’ adaptability is not known, although it can be raised horticulturally given the appropriate shade and moisture conditions. The species appears to be well adapted to flooding disturbance due to its proximity to the rivers and channels of the Nitinat, Klanawa and Carmanah river valleys. It may even require periodic flooding to maintain or create habitat as well as to aid in dispersal. Scouler’s corydalis’ tolerance to other types of disturbance and degradation is unknown. However, plants at the Cowichan-Nitinat junction are growing, and flowering, within a metre of the heavily used roadway. In addition, several populations near roads can be covered in thick layers of dust, as observed by the authors in 2003, and show no noticeable loss of vigour. Other populations are growing in roadside ditches that are periodically cleared to improve drainage. Such clearing could either create habitat or become a threat to the population depending on how often the ditch clearing was done.
It is not known why this species has such a limited distribution on Vancouver Island.
Population Sizes and Trends
Searches have been most intense to date in the Nitinat watershed, due to road accessibility, and this watershed contains the largest number of known extant sites. The first observation of Scouler’s corydalis in British Columbia was by W. Carter in 1915 on the Nitinat River. Through the 1970s to early 1990s, a number of observations/ collections were made on the Nitinat and Klanawa Rivers and along Nitinat Lake. Pavlick (1989) also searched without success the Gordon, San Juan and Klanawa drainages. The most intensive searches to date, and the first to document population sizes, were conducted in 1997 and 2003 (Douglas and Jamison 2000, Douglas and Smith 2003; respectively). All of the searches have been conducted by vehicle along logging roads and therefore focus on creeks and wetlands adjacent to these roadways. A small portion of the less accessible Klanawa watershed has been searched, near the convergence of the East Klanawa and Klanawa Rivers, and downriver in and around the Klanawa River Ecological Reserve.
Potential habitat on all the drainages has been estimated, based on the surveys conducted in the Nitinat drainage. There is an estimated 65 km2 of potential habitat along the Nitinat River, 18 km2 in the Klanawa drainage, 10 km2 around Cowichan Lake, and 9 km and 10 km2 along Carmanah and Walbran Creeks, respectively.
It is estimated that less than 50% of the potential habitat for Scouler’s corydalis in the Nitinat River drainage has been searched to date (Douglas and Smith 2003), mostly on the accessible westerly side of the river (Figure 4). Since searches have been in the form of sporadic point surveys, the populations, which often occur in bands along streams and rivers, are probably much larger and more continuous than has been recorded.
The Klanawa River drainage has yet to be adequately searched, with only three small areas, or about 10% of the entire area, searched (Douglas and Smith 2003). Recently, additional populations have been observed in the upper Cowichan Lake and Carmanah River drainages. It is likely that many more populations of Scouler’s corydalis will be found in these unsearched areas (see Figure 4) in the future.
There are presently 24 populations (36 sites) where Scouler’s corydalis has been observed (Table 2) in British Columbia within the last six years (1997 to 2004). These contain a total of about 848 000 stems. Since single clones may consist of numerous annual stems, spreading for at least tens of square metres (Ryberg, 1960), it is only possible to count stems and area covered to estimate population size. Stem counts by the authors were estimated after extrapolation from total counts made in 10 subpopulations in one-metre plots.Stem numbers range from one up to 462 000 per population. Seven of the populations have stem numbers over 20 000, which represent 95% of all the stems in British Columbia. The populations vary greatly in size from just a few square metres to 3.4 ha. Eight of the populations are over 0.5 ha in size. Total area currently occupied by these known populations is approximately 0.10 km2.
Using the ratio of area of extent to potential habitat found in the Nitinat drainage, it is estimated that there is an additional potential area of occupancy in the Klanawa, Carmanah, Walbran and Cowichan drainages totaling 0.143 km2.
The Conservation Data Centre recognizes Scouler’s corydalis in twenty-four populations or element occurrences in BC (J. Penny, pers. comm. 2006; Table 2). Populations are delineated from one another when they are separated by one kilometre or more. Five of the locations have not been mapped and therefore don’t have a number yet. Missing element occurrence numbers represent changes in spatial representation in the GIS and not a loss in numbers.
The number of stems in the populations of Scouler’s corydalis have not been adequately monitored. However, at the few sites that have been visited more than once over the last five years, the number of stems appears to be stable.
The nearest population of Scouler’s corydalis, outside of British Columbia, is on the Olympic Peninsula, approximately 80 km to the south; therefore natural immigration from this source is highly unlikely. These populations to the south are considered to be healthy as these species are not ranked (SNR) in Washington and Oregon. However, there have been no genetic studies between the United States and the Canadian populations to determine evolutionary relationships. Potential habitat exists in the adjacent watersheds of the Carmanah and Walbran Creeks.
|CDC Element Occurrence # (=population)||Sites (equal to subpopulations when more than one site per element occurrence)||Last Observation||Observer||Number of Stems/Area|
|No # yet||Cowichan 1||2004||Douglas||6/2 m2|
|7||Nitinat 1||2003||Douglas and Smith||34 700/5 784 m2|
|19||Nitinat 2||1997||Jamison||16/60m2 in 3 clusters|
|6||Nitinat 3||2003||Douglas and Smith||2 108/1 054 m2|
|6||Nitinat 4||2003||Douglas and Smith||1 000/60 m2|
|6||Nitinat 5||2003||Douglas and Smith||2 000/330 m2|
|24||Nitinat 6||2003||Douglas and Smith||1 350/120 m2|
|No # yet||Nitinat 7||2004||Penny and Ford||10/4 m2|
|No # yet||Nitinat 8||2003||Ferguson||No data|
|No # yet||Nitinat 9||2003||Ferguson||No data|
|5||Nitinat 10||2003||Douglas and Smith||18 000/1 600 m2|
|23||Nitinat 11||2003||Douglas and Smith||150/15 m2|
|2||Nitinat 12||2003||Douglas and Smith||50/150 m2|
|2||Nitinat 13||2003||Douglas and Smith||40/150 m2|
|3||Nitinat 14||2003||Douglas and Smith||462 600/34 068 m2|
|4||Nitinat 15||1998||Douglas||2 000/5 000 m2|
|4||Nitinat 16||2003||Douglas and Smith||2 000/7 000 m2|
|4||Nitinat 28||2003||Douglas and Smith||44 850/24 800 m2|
|13||Nitinat 17||2003||Douglas and Smith||94 800/7 900 m2|
|13||Nitinat 18||2003||Douglas and Smith||21 867/7 275 m2|
|13||Nitinat 19||2003||Douglas and Smith||6 820/1 026 m2|
|21||Nitinat 20||2003||Douglas and Smith||540/36 m2|
|16||Nitinat 21||1997||Jamison||1 000/1 000 m2|
|17||Nitinat 22||2003||Douglas and Smith||105 700/5 000 m2|
|17||Nitinat 23||2003||Douglas and Smith||5/6 m2|
|18||Nitinat 24||2003||Douglas and Smith||60/60 m2|
|18||Nitinat 25||2003||Douglas and Smith||44 000/5 500 m2|
|18||Nitinat 26||1997||Jamison||100/60 m2|
|1||Nitinat 27||2003||Douglas and Smith||1 080/300 m2|
|10||Klanawa 1||2003||Hoyt||1 700/920 m2|
|15||Klanawa 2||1997||Roemer||12 pls|
|15||Klanawa 3||1998||Douglas||14/10 m2|
|15||Klanawa 4||2004||Douglas||4/2m 2|
|20||Klanawa 5||1998||Douglas||2/5 m2|
|11||Klanawa 6||1998||Douglas||1/1 m2|
|No # yet||Carmanah 1||2004||MacKinnon||7/500 m2|
|Total||848 592 stems|
See Figure 4 for site locations.
Limiting Factors and Threats
An extensive network of logging roads has made large areas much more accessible in the Nitinat River and Klanawa River drainages. Current potential threats to Scouler’s corydalis, from logging, road and bridge building, recreational use and natural flooding are probably minor. These threats will have less impact on the total populations of Scouler’s corydalis since there are now known to be over 800 000 stems over a 275 km2 area. As well, Wildlife Habitat Areas prohibit logging, road and bridge building within the designated wildlife areas that protect over 400 000 stems. Road building and bridges have damaged some Scouler’s corydalis populations in the past; however, the total percentage of the population removed has been low. Some riverbank damage occurs when recreationalists have easy access to the rivers, but this is very minor at this time. Since the 1950s logging had a minimal direct effect on populations as this species rarely grows in harvestable forests. However, previous to this time in the early 1900s the equipment used in the removal of old growth stands could have reduced populations substantially.
Natural flooding, from time to time, removes riverbanks and floodplain populations. This would usually result in only temporary population reduction since the flooding creates new habitat and would provide a dispersal mechanism.
It is unknown whether inbreeding depression is a threat to the survival of Scouler’s corydalis populations. More research is needed on genetics and sexual and asexual reproduction to determine the risk of this threat. In addition, if sexual reproduction is important for the species, pollinator loss may be a threat.
Scouler’s corydalis is readily available in the horticultural trade, and because it is easy to obtain plants, collecting is not considered a threat.
Special Significance of the Species
Gardeners in both North America and Europe value highly several species of Corydalis for both flowers and foliage. Ownbey (1947), in his seminal monograph on the genus, especially recommended C. caseana ssp. brandegei and ssp. cusickii, noting that European gardeners had already discovered C. scouleri, C. aurea, and C. sempervirens.
In addition, the alkaloidal properties of a large number of members of both the fumitory and the closely related poppy family are of great interest to plant taxonomists, plant chemists, and agronomists. Each species has been found to contain a unique set of alkaloids, some of which are common to other species, but not in the same combinations. Agronomists consider these properties significant in that they probably render the plants toxic to livestock; a bitter taste likely makes them unpalatable in any event (Ownbey, 1947).
Existing Protection or Other Status Designations
Scouler’s corydalis is not covered under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the Endangered Species Act (USA) or the IUCN Red Data Book. Globally, Scouler’s corydalis has a rank of G4, defined as “frequent to common (greater than 100 occurrences); apparently secure but may have a restricted distribution; or there may be perceived future threats” (NatureServe 2006b).
This species is not tracked as a rare species outside of British Columbia. In Washington and Oregon, the only other jurisdictions in which it occurs, it is ranked SNR (NatureServe 2006b) indicating that the species has not yet been assessed.
Since the species is restricted to British Columbia in Canada, it has a national rank of N3N4. It was assessed by COSEWIC as threatened in 2001, and is on Schedule 1 of the federal Species at Risk Act. Provincially,Scouler’s corydalisis ranked by the British Columbia Conservation Data Centre as S3S4 and has recently been moved from the British Columbia Ministry of Environment red list to the blue list (J. Penny, pers. comm. 2005).
Scouler’s corydalis could be a candidate for protection in British Columbia under the provincial Wildlife Amendment Act (2004) as it is currently blue-listed by the provincial Conservation Data Centre and because of its national listing.
Two of the populations of C. scouleri in British Columbia are protected by the Provincial Park Act since they occur in Provincial Parks (Carmanah-Walbran and Nitinat River), and the Klanawa River Ecological Reserve (#138) is protected under the Ecological Reserves Act. The Provincial Park Act protects the species from the threat of forestry management activities. Under the Government Actions Regulation of the Forest and Range Practices Act (FRPA) of British Columbia, management for selected species and plant communities can be established by designating Wildlife Habitat Areas. This species is also listed under the Identified Wildlife Management Strategy under FRPA, which allows WHAs to be utilized. Wildlife Habitat Areas have been designated for eight Scouler’s corydalis sites in the Nitinat and East Klanawa River drainages. Wildlife Habitat Areas are legal entities although stand maintenance can be permitted to retain a particular seral stage such as that required by Scouler’s corydalis.
In addition, both forestry firms operating in the different drainages have recorded all British Columbia Conservation Data Centre information in their GIS systems and consult this information during tree harvest planning (Bill Beese, pers. comm.; Bo Ferguson, pers. comm.).
Range of Occurrence in Canada: BC
Extent and Area Information
- extent of occurrence including potential extent of occurrence
Specify trend in EO
Are there extreme fluctuations in EO?
Area of occupancy (AO) (km2)
- total area of surveyed populations
- area of occupancy including estimated area of potential occupancy
Specify trend in AO
Are there extreme fluctuations in AO?
Number of known or inferred current locations
Specify trend in #
Are there extreme fluctuations in number of locations?
Specify trend in area, extent or quality of habitat
Number of mature individuals
Ca. 848 000 stems estimated but likely >1 million when additional suitable but inaccessible habitat is considered
Total population trend:
% decline over the last/next 10 years or 3 generations.
Are there extreme fluctuations in number of mature individuals?
Is the total population severely fragmented?
Specify trend in number of populations
Are there extreme fluctuations in number of populations?
List populations with number of mature individuals in each: (see Table 2)
Threats (actual or imminent threats to populations or habitats)
Limited impact from road and bridge construction, trampling by recreationalists, logging, flooding and inbreeding depression.
Rescue Effect (immigration from an outside source)
Is immigration known or possible?
Unknown but unlikely
Would immigrants be adapted to survive in Canada?
Is there sufficient habitat for immigrants in Canada?
Is rescue from outside populations likely?
[provide details on calculation, source(s) of data, models, etc]
COSEWIC: Threatened (2001)
COSEWIC: Not at Risk (2006)
Status and Reasons for Designation
Reasons for Designation: A conspicuous perennial herb of riverside habitats that is restricted to a small region of south-western Vancouver Island. The species was previously assessed as threatened but is now known to be present at additional locations and is much more abundant than previously documented. There is no evidence of population decline or fluctuation and no significant threats appear to affect the species. More than one-half of the population is now in protected areas specifically managed for this species and, since extensive areas of suitable habitat remain to be surveyed, additional populations will likely be discovered.
Applicability of Criteria
Criterion A (Declining Total Population):
NA. No evidence of decline > 30%.
Criterion B (Small Distribution, and Decline or Fluctuation):
NA. Extent of occurrence and area of occupancy below critical levels but > 5 sites and these not severely fragmented and no continuing decline or extreme fluctuations documented.
Criterion C (Small Total Population Size and Decline):
NA. Although actual numbers of discrete plants is unknown, with 848 000 stems estimated, and likely more to be found, it is highly likely that there are >>10 000 plants present.
Criterion D (Very Small Population or Restricted Distribution):
NA. There are >> 1000 plants and > 5 sites; although the area of occupancy is << 20 km2, there are no significant threats currently that would place the species at risk of becoming highly endangered in a short period of time. Recent fieldwork has confirmed that the population is more widely distributed than previously known; it is at least seven times larger than previous estimates and more than half of the population is now in protected areas managed specifically for this species. Additional suitable areas of difficult to access habitat also remain to be explored.
Criterion E: (Quantitative Analysis):
Acknowledgements and Authorities Consulted
Ms. Jenifer Penny. January 2004. British Columbia Conservation Data Centre, Wildlife Inventory Section, Resources Inventory Branch, Ministry of Environment, Lands and Parks, P.O. Box 9344, Station Provincial Government, Victoria, BC V8W 9M1.
Beese, Bill, pers. comm. 2003. Forest Ecologist, BC Coastal Group, Weyerhaeuser, Nanaimo, BC.
Brockman, C.F. 1947. Flora of Mount Rainier National Park. United States Government Printing Office, Washington, D.C.
Douglas, G.W., and J.A. Jamison. 2000. Status report on Scouler’s Corydalis, Corydalis scouleri (Fumariaceae) in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-18 pp.
Douglas, G.W., D. Meidinger and J. Pojar. 1999a. Illustrated flora of British Columbia, Volume 3 (Dicotyledons, Diapensiaceae through Onagraceae). Ministry of Environment, Lands and Parks, Ministry of Forests. Victoria, British Columbia. 423 pp.
Douglas, G.W., D. Meidinger and J. Pojar. 2000. Illustrated flora of British Columbia. Volume 5 (Salicaceae through Zygophyllaceae). Ministry of Environment, Lands and Parks, Ministry of Forests. Victoria, British Columbia. 389 pp.
Douglas, G.W., and S.J. Smith. 2003. Corydalis Inventory – Field Report and Summary. Unpublished report. Biodiversity Branch, Ministry of Environment, Lands and Parks, Victoria, British Columbia. 3 pp. + Excel file.
Ferguson, Bo. pers. comm. 2003. Engineer, TimberWest, Nanaimo, BC
Forest and Range Practices Act. 2002. Ministry of Forests. http://www.for.gov.bc.ca/tasb/legsregs/frpa/frpa/frpatoc.htm
Fraser, D.F. pers. obs. 2006. Endangered Species Specialist. Biodiversity Branch, Terrestrial Ecosystem Science Section, Ministry of Water, Land and Air Protection, Government of British Columbia , P.O. Box 9338, Station Prov. Govt., Victoria, BC V8W 9M1.
Hanzawa, F.M., A.J. Beattie, and D.C. Culver. 1988. Directed dispersal: demographic analysis of an ant-seed mutualism. The American Naturalist 131(1):1-13.
Hanzawa, F.M., A.J. Beattie, and A. Holmes. 1985. Dual function of the elaiosome of Corydalis aurea (Fumariaceae): attraction of dispersal agents and repulsion of Peromyscus maniculatus, a seed predator. American Journal of Botany 72(11):1707-1711.
Hartwell, S., and K. Paige. 2004. Accounts and Measures for Managing Identified Wildlife – Scouler’s corydalis, Corydalis scouleri. Unpublished report. Biodiversity Branch, Ministry of Environment, Lands and Parks, Ministry of Forests. Victoria, British Columbia. 6 pp.
Hitchcock, C.L., A. Cronquist, M. Ownbey, and J.W. Thompson. 1969. Vascular Plants of the Pacific Northwest--Part 2: Salicaceae to Saxifragaceae. University of Washington Press, Seattle. 914 pp.
Liden, M. 1986. Synopsis of Fumarioideae (Papaveraceae) with a monograph of the tribe Fumarieae. Opera Botanica 88: 1–133.
NatureServe Explore. 2006a. NatureServe Explorer: An online encyclopedia of life [web application]. Version 4.7. NatureServe, Arlington, VA: NatureServe. http://www.natureserve.org/explorer. See Products and Services, Element Occurrence Data Standard. [accessed May 2006].
NatureServe Explorer. 2006b. NatureServe Explorer: An online encyclopedia of life [web application]. Version 4.7. NatureServe, Arlington, VA: NatureServe. [accessed May 2006].
Ohkawara, K., M. Ohara, and S. Higashi. 1997. The evolution of ant-dispersal in a spring-ephemeral Corydalis ambigua (Papaveraceae): timing of seed-fall and effects of ants and ground beetles. Ecography 20:217-223.
Ownbey, G.B. 1947. Monograph of the North American species of Corydalis. Annals of the Missouri Botanical Garden 34: 187–259.
Pavlick, L.E. 1989. Scouler’s Corydalis--one of B.C.’s rare and beautiful plants. The Victoria Naturalist 45(6): 17.
Penny, J. pers. comm. 2005, 2006. Botanist. British Columbia Conservation Data Centre, Wildlife Inventory Section, Resources Inventory Branch, Ministry of Environment, Lands and Parks.
Pojar, J., K. Klinka and D.A. Demarchi. 1991. Coastal Western Hemlock Zone. Pages 95-111 in Ecosystems of British Columbia. Edited by D. Meidinger and J. Pojar. British Columbia Ministry of Forests Special Report Series No. 6, Victoria, British Columbia. 330 pages.
Ryberg, M. 1960. A morphological study of the Fumariaceae and the taxonomic significance of the characters examined. Acta Horti Bergiani 19(4): 121–248.
Smith, S. pers. comm. 2006. Ecological Consultant, 314 Becher Bay Road, Sooke, BC, V0S 1N0. Tel: (250) 896-4179. Email: email@example.com
George W. Douglas (deceased) had an M.Sci. (Forestry) from the University of Washington and a Ph.D (Botany) from the University of Alberta, Edmonton. George worked with rare plants for over 25 years. He was senior author of The Rare Plants of the Yukon (1981), The Rare Plants of British Columbia (1985) and Rare Native Plants of British Columbia (1998, 2002). He was also the senior editor for the Illustrated Flora of British Columbia (1998-2002) and was the program botanist for the British Columbia Conservation Data Centre from 1991 until 2003. George wrote or co-wrote 33 COSEWIC status reports and three update status reports during this period.
Shyanne J. Smith has a B.Sc. (Geography) from the University of Victoria. She has conducted botanical inventory, research, and mapping projects in British Columbia since 2001. Shyanne co-authored the National Recovery Plan for Southern Maidenhair Fern (2003), and the draft National Multi-species Recovery Strategy for Species at Risk in Garry Oak Woodlands (2005). She has also co-authored a number of COSEWIC status reports.
Brenda Costanzo, Jeff Hoyt and David F. Fraser are biologists with the BC Ministry of Environment. Brenda is the chair of the Scouler’s Corydalis Recovery Team and has authored/co-authored several COSEWIC status reports.
Collections were examined at the University of British Columbia, Royal British Columbia Museum, National Museum (Ottawa) and Department of Agriculture (Ottawa).
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