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Recovery Strategy for Multi-Species at Risk in Vernal Pools and other Ephemeral Wet Areas Associated with Garry Oak Ecosystems in Canada (Proposed)


3. Species Background

3.1 Bog bird's-foot trefoil

Common Name: Bog bird's-foot trefoil

Scientific Name: Lotus pinnatus Hook

Current status and most recent date of assessment: Endangered, May 2004

Reason for designation: Few small fragmented populations that are geographically restricted and found within wetland meadows of limited occurrence and considerably disjunct from the main range of the species in the northwestern United States. Populations are at risk from continued habitat loss and encroachment of invasive species and from recreational off-road vehicular activities with the likelihood of significant losses due to planned commercial development of habitat supporting the only sizeable remaining population.

Occurrence: BC

3.1.1 Description of the species

Bog bird's-foot trefoil is a short-lived perennial of the pea family (Fabaceae) with numerous erect or sprawling stems ranging from 15–60 cm long. The leaves are pinnately compound with 5-9 elliptic, oblong or egg-shaped leaflets, each 1 –2 cm long. The leaves are 4–8 cm long. The flower heads are umbels consisting of 3-12 flowers. The flowers are cross-pollinated and are 10–15 mmlong with a yellow banner and keel, and white wings. The calyx is tubular and lobed, with two upper lobes that are joined most of their length. The linear seed pods range are 3–6 cm long and 1.5–2 mm cylindrical, glossy, dark-coloured seeds (Douglas et al. 1999a). Seeds germinate in the late winter or early spring, with flowering generally occurring between May and the end of June (Donovan 2004).

Little information is available on the ecological dynamics of bog bird's-foot trefoil. Life history traits such as recruitment rates, age-specific survivorship, life span, generation time, and longevity of seeds in the soil are all unknown.

Bog bird's-foot trefoil is of minor economic significance in Canada: at least one native seed supplier on Vancouver Island is known to have stocked wild-collected bog bird's-foot trefoil seed in the past. Seeds can also be purchased through online seed catalogues in the U.S., presumably for horticultural purposes (Donovan 2004).

3.1.2 Distribution and status

The global range of bog bird's-foot trefoil extends from Vancouver Island south to northwest Washington, western Oregon and the Columbia River Gorge, central California, and sporadically eastward as far as Idaho. In Canada, bog bird's-foot trefoil is restricted to a small area of southeastern Vancouver Island around Nanaimo, and to Gabriola Island just off of Nanaimo (Table2, Fig. 1).

Bog bird's-foot trefoil has a global conservation ranking of G4G5. It is ranked SNR (unranked) in California, Washington, Oregon, and Idaho (NatureServe 2005). The COSEWIC status report (Donovan 2004) estimates the Canadian extent of occurrence (EO) to be approximately 100 km², and the current area of occupancy (AO) to be 0.06 ha. This likely represents <1 percent of the species' total global distribution.

3.1.3 Habitat

In southern Washington and Oregon, bog bird's-foot trefoil is found from sea level to higher elevations in the mountains, often along slow-moving streams that dry up by mid-summer (Table 9) (Peck 1961; Hitchcock and Cronquist 1973, Jolley 1988). The species is also well established in the wet prairie communities of the Willamette and Umpqua Valleys and the southern Puget Trough. In California, bog bird's-foot trefoil occurs in a variety of habitats including wet meadows, bogs, ditches and stream beds (Isely 1993). It is federally classified as a "facultative wetland" species, the designation given to taxa that usually (with 67% to 99% probability) occur in wetlands but are occasionally found in non-wetlands (USDA-NRCS 2004).

In Canada, bog bird's-foot trefoil is confined to vernal seeps, vernally wet meadows, creek margins, and other microsites that receive abundant moisture through the spring but dry out during the summer (Table 9) (Douglas et al. 1999b, Donovan 2004). It is sometimes found at the margins of shrub thickets with Nootka rose (Rosa nutkana), ocean spray (Holodiscus discolor), and Pacific ninebark (Physocarpus capitatus). Plants have also been found growing in mineral soil within old tire ruts, in organic soils at the edge of a logged area, and in scattered openings within a Douglas-fir/arbutus forest. Other commonly associated species include yellow monkey-flower (Mimulus guttatus), sea-blush (Plectritis congesta), fool's onion (Triteleia hyacinthina), small-leaved montia (Montia parvifolia), Scouler's popcornflower (Plagiobothrys scouleri) and American brooklime (Veronica beccabungassp. americana).

The soil at Harewood Plains, site of the largest population, is a generally shallow (<15 cm deep) Lithic Dystric Brunisol overlying gently sloping sandstone or conglomerate bedrock of the Nanaimo formation (Jungen et al. 1985). However, detailed information is lacking on the requirements of bog bird's-foot trefoil with respect to microsite attributes such as soil texture, soil depth, moisture levels, nutrient content, soil bacteria (e.g., Rhizobia), pH levels, length and timing of inundation, and disturbance regimes (Table 9).

3.1.4 Population size and trends

The COSEWIC status report identifies seven extant populations and numerous sub-populations. As of 2003, population counts ranged from 10 to about 1500 flowering stems, combining for an estimated total population of 1500-2000 plants. However, this is a rough estimate only because the clumped, sprawling habit of bog bird's-foot trefoil makes it difficult to identify separate individuals. The actual number of genetic individuals (genets) is likely much lower than this (Donovan 2004).

Recent attempts to confirm two historical records for bog bird's-foot trefoil at sites near Nanaimo have been unsuccessful, and these populations are believed extirpated (Table 2). At the Extension Rd. site, near Nanaimo, at least some portions of the population are believed to have recently been extirpated due to a combination of recreational off-road vehicle use and residential development (A. Ceska, pers. comm. 2004). Beyond these recorded or suspected losses, however, there is little information on long-term-population trends for bog bird's-foot trefoil in Canada.

Figure 1. Distribution of bog bird's-foot trefoil in North America (left) and in British Columbia (right).
(Solid circles: extant range. Open circle: historical range.)
Figure 1. Distribution of bog bird's-foot trefoil in North America (left) and in British Columbia (right). (Solid circles: extant range. Open circle: historical range.)

3.2 Tall woolly-heads (Pacific population)

Common Name: Tall woolly-heads

Scientific Name: Psilocarphus elatiorGray

Current status and most recent date of assessment: Endangered (Pacific population), May 2001

Reason for designation: Small annual species present in major urban area within Garry oak habitats with few small scattered populations subject to fluctuating numbers and at risk from habitat degradation and loss.

Occurrence: BC

3.2.1 Description of the species

Tall woolly-heads is a small annual herb in the aster, or sunflower, family (Asteraceae). The erect stems are densely covered with woolly hair, and range from 1–15 cm tall. The leaves are hairy, opposite, and linear to oblong in shape. The flowers occur in spherical heads up to 6 mm wide. The heads occur by themselves or in clusters at the forks and tips of branches. The fruits are cylindric, brown achenes 1.0–1.7 mm long, and lack a pappus. Seedlings emerge in early spring, with flowers developing by early to mid-summer. The plants are slow to whither and usually remain visible until late summer.

One other species Psilocarphus, slender wooly-heads (P. tenellus var. tenellus), occurs in moist vernal sites on Vancouver Island. Tall woolly-heads is distinguished from the latter by its upright habit, larger heads and larger receptacle bracts (Douglas et al. 2001a).

Little information exists regarding the biology of the species. Lack of structures attractive to insects and animals, and the type of floral structure, suggest that the species may self-pollinate. However, pollen may not be essential for seed production, and asexual reproduction may also occur (Douglas et al. 2001a). The longevity of seeds in the soil is unknown but, given the annual life cycle and variable habitat conditions, existence of a seed bank can be presumed. Cox and Austin (1990) found good recovery of the related interior species P. brevissimus following a burn treatment; however, the response of tall woolly-heads to fire has not been documented. Tall woolly-heads is of no economic or social significance in Canada.

3.2.2 Distribution and status

In Canada, tall woolly-heads has been reported from southwestern British Columbia, southeastern Alberta and southwestern Saskatchewan.6 In the U.S., tall woolly-heads occurs from the Puget trough region of western Washington south to northern California and in the mountains of northeastern Oregon, southeastern Washington, and adjacent Idaho. Within Canada, the Pacific population is restricted to southeastern Vancouver Island7 (Table 2, Fig. 2). Tall woolly-heads has a global conservation ranking of G4. It is ranked S3 in California and SNR (unranked) in Washington, Oregon, and Idaho, S2 in Alberta, and S1S2 in Saskatchewan (NatureServe 2005). The Canadian prairie population has been designated by COSEWICas "special concern." The extent of occurrence (EO) of the Pacific population is approximately 300 km², and the area of occupancy (AO) is approximately 1,500 . This represents &lt;1 percent of the species' total Pacific distribution.

3.2.3 Habitat

In the U.S., tall woolly-heads is federally classified as a "facultative wetland" species, the designation given to taxa that usually (with 67% to 99% probability) occur in wetlands but are occasionally found in non-wetlands (USDA-NRCS 2004).

On Vancouver Island and elsewhere in the Pacific Northwest, tall woolly-heads is known from low-elevation vernal pools and other open, sometimes disturbed, vernally moist places (Table 9) (Peck 1961, Hitchcock and Cronquist 1973, Jolley 1998, Morefield 1993, Douglas et al. 2001a, CDC HERB Database 2004). However, detailed information is lacking on the local requirements and tolerances of tall woolly-heads with respect to microsite attributes such as soil texture, soil depth, moisture levels, nutrient content, pH levels, length and timing of inundation, and disturbance regime (Table 9).

(Danthonia californica), Scouler's popcornflower (Plagiobothrys scouleri), heterocodon (Heterocodon rariflorum) and greensheathed sedge (Carex feta) (BC HERB Database 2004). The highly invasive colonial bentgrass* (Agrostis capillaris) is well established in the bottom of the pool and poses a potential major threat to tall woolly-heads survival.

At Somenos Marsh, tall woolly-heads occurs in a narrow, 5 m wide band parallel to the creek in a patchy zone of open, silty soil that is apparently maintained by winter flooding (Roemer 2004). Sedges form the dominant vegetation within this zone, although the provincially red-listed needle-leaved navarretia (Navarretia intertexta) and the blue listed (and COSEWICSpecial Concern) Vancouver Island beggar-ticks (Bidens amplissima) are also present (Roemer and Fairbarns 2003).

Tall woolly-heads is known from two geographically separate and more or less distinct habitat areas within Uplands Park. These are the remnant Garry oak woodlands that comprise the core of the park; and Cattle Point, a rocky marine bluff at the edge of the park. Within the former area, tall woolly-heads occurs in scattered subpopulations on the dry beds of small vernal pools on soils ranging from dark organic to bare mineral, often in association with lowland cudweed (Gnaphalium palustre). It is also found in old tire ruts and depressions within the large vernal swale in the central meadow. The soil in this part of the park is predominantly developed on poorly drained, medium to fine textured marine materials overlying marine clay, and is referred to as Tolmie soi (Day et al. 1959, Collier et al. 2004). At Cattle Point, tall woolly-heads occurs in shallow depressions 5 to 10 m in diameter, in hard, compacted loamy sand over an impermeable gravelly loam till (a soil type known as Langford; Day et al. 1959), with red sandspurry (Spergularia rubra) and paintbrush owl-clover (Castilleja ambigua). These depressions have been invaded to considerable degree by nonnative grasses such as hedgehog dogtail* (Cynosurus echinatus), perennial ryegrass* (Lolium perenne), and annual bluegrass* (Poa annua). Other species associated with tall woolly-heads at one or other site include Kellogg's rush; the two red-listed (and COSEWIC-candidate) species winged water-starwort (Callitriche marginata) and Muhlenberg's centaury (Centaurium muehlenbergii); and toad rush (Juncus bufonius), blue camas (Camassia quamash), foxtail (Alopecurus spp.), and creeping bentgrass* (Agrostis stolonifera) (Douglas et al. 2001a, BC Conservation Data Centre 2003).

3.2.4 Population size and trends

The COSEWICstatus report describes four extant populations and numerous sub-populations (at Uplands Park). Two of the populations (Uplands Park and Cattle Point) are separated by &lt;1 km, and for the purposes of this recovery strategy are treated as a single population (Table 2). Reported population counts for different localities range from 400 to >2,000,000 individuals (CDC HERB Database 2004, Roemer and Fairbarns 2003, Roemer 2004). As with most annual species, however, plant densities at any given site likely fluctuate substantially from year to year in response to changing microsite conditions, precipitation patterns, seed bank dynamics, and density-dependent feedbacks. Best recent available information suggests a total population size (not counting dormant seeds) in Canada of >1,000,000 individuals, although this estimate may need to be revised downward in light of recent damage done to the population at Somenos Marsh (Section 2.6.1).

In addition to the three known populations, tall woolly-heads has been reported from seven other sites on Vancouver Island (Table 2). Of these, six sites are now presumed extirpated, while the status of another has not been recently confirmed and may also be extirpated. Beyond these recorded losses, however, there is no reliable long-term information on population trends for tall woolly-heads in Canada.

Figure 2. Distribution of tall woolly-heads (Pacific population) in North America (left) and in British Columbia (right).
(Solid circles: extant range. Open circles: historical range.)
Distribution of tall woolly-heads (Pacific population) in North America (left) and in British Columbia (right). (Solid circles: extant range. Open circles: historical range.)

3.3 Kellogg's rush

Common Name: Kellogg's rush

Scientific Name: Juncus kelloggiiEngelm.

Current status and most recent date of assessment: Endangered, May 2003

Reason for designation: This is a tiny, inconspicuous, annual species that likely numbers fewer than 600 plants. It occurs in a single, seasonally wet microhabitat that is subject to impacts from human recreational and developmental activities within an urban park located in a nationally rare Garry Oak habitat.

Occurrence: BC

Status history: Designated Endangered in May 2003. Assessment based on a new status report.

3.3.1 Description of the species

Kellogg's rush is a small annual rush (grass-like plants in the family Juncaceae) with erect stems ranging from 0.4 to 4 cm tall. The leaves emerge from the base of the stem and are bristle-like. Flowers occur singly or in pairs at the top of the stem. The fruit is a blunt capsule, about as long as the perianth (flower) segments. The seeds are about 0.4 mm long. Kellogg's rush is usually visible between April and July, although due to its small size, the species is easily overlooked in the field.

In the field, Kellogg's rush could be confused with toad rush (Juncus bufonis), another small annual rush. The latter species has an involucral bract that appears as a continuation of the stem, whereas Kellogg's rush possesses only scalelike involucral bracts (Douglas et al. 2001b' Costanzo, 2003).

Little information is available on the ecology or population dynamics of Kellogg's rush. The species is thought to be self-pollinating, and each capsule contains approximately 50 seeds (Ertter 1986). In greenhouse germination trials, not all seeds germinated in the same year, implying the existence of a persistent seed bank (Ertter 1986). Population size of the single known occurrence at Uplands Park has been known to fluctuate dramatically between years, presumably in response to fluctuations in seasonal precipitation (Costanzo 2003).

The species has no special economic or social significance in Canada.

3.3.2 Distribution and status

Kellogg's rush is known from extreme southern Washington, western Oregon, Nevada, and California west of the Sierra Nevada. The lone Canadian population on southern Vancouver Island (Table 2), is separated by 330 km from the nearest population in Washington State (Fig. 3). Kellogg's rush has a global conservation ranking of G3. It is listed as SNR (not ranked) in California and Nevada, SU (unrankable) in Oregon, and S1 in Washington (NatureServe 2005).

The COSEWIC status report (Costanzo 2003) estimates both the extent of occurrence (EO) and area of occupancy (AO) in Canada to be approximately 25 . This presumably represents &lt;1 percent of the species' total global distribution.

3.3.3 Habitat

Across its range, Kellogg's rush is found on sandy and clayey damp soils around vernal pools, seasonally wet depressions, seepage areas, and damp fields and meadows up to 800 m (Peck 1961, Hitchcock and Cronquist 1973, Brooks and Clements 2000, Douglas et al. 2001b). In the U.S. it is federally classified as a "facultative wetland" species, the designation given to taxa that usually (with 67% to 99% probability) occur in wetlands but are occasionally found in nonwetlands (Table 9; USDA-NRCS 2004).

In British Columbia, Kellogg's rush is known from a single depression within a seasonally flooded Garry oak meadow, at an elevation of 10 m. Trees are absent, presumably due to the wetness of the habitat. The soil beneath the population has not been profiled but is likely a poorly drained Tolmie or Gleysol developed from medium to fine textured marine materials overlying marine clay parent material (Day et al. 1959, H. Roemer, pers. comm. 2005). The associated herb layer contains a mix of native and nonnative forbs including tall woolly-heads, Muhlenberg's centaury (Centaurium muhlenbergii), winged water-starwort (Callitriche marginata), blue camas (Camassia quamash), toad rush (Juncus bufonius), chaffweed (Anagallis minima), and heterocodon (Heterocodon rariflorum). Introduced grasses such as soft brome* (Bromus hordeaceus), hedgehog dogtail* (Cynosurus echinatus), common velvet-grass* (Holcus lanatus), and orchard grass* (Dactylis glomerata) are also present (BC Conservation Data Centre 2003). However, more information is required on microsite attributes such as soil texture, soil depth, moisture levels, nutrient content, pH levels, length and timing of inundation, and disturbance regimes (Table 9). However, more information is required on microsite attributes such as soil texture, soil depth, moisture levels, nutrient content, pH levels, length and timing of inundation, and disturbance regimes (Table 9).

3.3.4 Population size and trends

The COSEWIC report states that since the early 1990's, when monitoring of Kellogg's rush first began at Uplands Park, annual population counts have ranged from as many as 200-600 individuals (in 1999) to as few as 3 (in 2001). A more recent survey undertaken in 2003 yielded an estimate of 1000-1500 individuals (A. Ceska, pers. comm. 2004). Beyond these minimal data, there is no information on long-term population trends for Kellogg's rush in Canada.

Figure 3. Distribution of Kellogg's rush in North America (left) and in British Columbia (right).
Figure 3. Distribution of Kellogg's rush in North America (left) and in British Columbia (right).

3.4 Water-plantain buttercup

Common Name: Water-plantain buttercup

Scientific Name: Ranunculus alismifolius Geyer ex Benth. var. alismifolius

Current status and most recent date of assessment: Endangered, May 2000

Reason for designation: Only two remaining populations of approximately 70 individuals threatened by recreational activities and competition from exotic plants.

Occurrence: BC

Status history: Designated Endangered in April 1996. Status re-examined and confirmed in May 2000. Last assessment based on an existing status report.

3.4.1 Description of the species

Water-plantain buttercup is a perennial herb of the buttercup family (Ranunculaceae). The flowers occur singly at the ends of the stalks. The bright yellow petals are up to 1 cm long, about 3 times as long as the sepals. Basal leaves are broadly lanceolate to egg-shaped and sometimes toothed, while the stem leaves are smooth and linear. The stems are upright, often branched, usually rather stout, up to; 60 cm tall, smooth, and hollow, and arise from several thickened roots. In contrast to many buttercup species, the stems do not root at the nodes. The fruits are smooth achenes, 10-60 in a small spherical head and with short, curved to straight beaks (Hitchcock et al. 1964). Vegetative growth appears in early spring with flowers emerging in April and May and seeds maturing in June. During July, when drought conditions are prevalent, the foliage diesback and the plants become dormant until the following year.

Aside from basic habitat relationships, little information is available on the ecology of the species (Illingworth and Douglas 1994), including pollination ecology, competitive ability, and life history traits such as recruitment rates, age-specific survivorship, life span, generation time, and longevity of seeds in the soil.

Water plantain-buttercup is of no known economic or social significance in Canada. However, seeds of water-plantain buttercup can be purchased through at least one online seed catalogue in the U.S., presumably for horticultural purposes. In Oregon, the seeds have been used as a component of seed mixes sown for wetland prairie restoration (City of Eugene 2002).

3.4.2 Distribution and status

The global range of water-plantain buttercup extends from the Gulf Islands southward through Washington, Idaho, and western Montana to Oregon and north-eastern California (Hitchcock et al. 1964, Illingworth and Douglas 1994, Douglas and Illingworth 1998) (Fig. 4). It is common in most northwest Pacific states. However, in Canada, the species is known from just two locations: Uplands Park in Oak Bay (Greater Victoria), and Ballenas Island off the southeast coast of Vancouver Island (Table 2, Fig. 4). Herbarium labels for Victoria from the late 19th century refer to two vague locations: "Oak Bay" and "Cadboro Bay Rd." These sites are either extirpated or represent earlier records of the single extant site at Uplands Park (Illingworth and Douglas 1994).

Water-plantain buttercup has a global conservation ranking of G5T5. It is ranked SNR (unranked) in California, Washington, Idaho, Oregon, Montana, Nevada, and Wyoming (NatureServe 2005). The Canadian extent of occurrence (EO) of water-plantain buttercup is approximately 2.8 km², and the total area of occupancy (AO) is approximately 4 . This represents &lt;1 percent of the species' total distribution.

3.4.3 Habitat

Across its range, water-plantain buttercup is found in swampy ground around lakes and mudflats, along streams and roadside ditches, and in wet prairies and meadows from sea level up to 2300 m in the subalpine (Peck 1961, Hitchcock and Cronquist 1973, Jolley 1988, Wilken 1993, Whittemore 1997, Douglas et al. 1999b). In the U.S., it is federally classified as a "facultative wetland" species, the designation given to taxa that usually (with 67% to 99% probability) occur in wetlands but are occasionally found in non-wetlands (USDA-NRCS 2004). However, detailed information is lacking on the requirements and tolerances of this species with respect to microsite attributes such as soil texture, soil depth, moisture levels, nutrient content, pH levels, length and timing of inundation, and disturbance regimes (Table 9).

In Canada, water-plantain buttercup is currently known only from low-elevation vernal pools and wet Garry oak meadows (Table 9). At Uplands Park it grows in two separate locations: along a muddy trailside at the edge of a seasonably flooded grassy swale; and in a small wet depression about 200 meters southwest of the first site. The herb layer at the two locations is dominated by a mix of native and introduced forbs and grasses. Associated native species include tall woolly-heads, blue camas (Camassia quamash), rose (Rosa sp.), fool's onion (Triteleia hyacinthina), western buttercup (Ranunculus occidentalis) and graceful cinquefoil (Potentilla gracilis). Non-native, invasive species include creeping buttercup* (R. repens), English plantain* (Plantago lanceolata), English hawthorn* (Crataegus monogyna), soft brome* (Bromus hordeaceus), hedgehog dogtail* (Cynosurus echinatus), common velvet-grass* (Holcus lanatus), and orchard grass* (Dactylis glomerata). Soils are a poorly drained Tolmie or Gleysol developed from medium to fine textured marine materials overlying marine clay parent material (Day et al. 1959, H. Roemer, pers. comm. 2005).

On Ballenas Island, water-plantain buttercup grows in shallow mud within two small, vernally wet depressions at the base of a seepage area, next to an aspen Populus tremuloides) grove and surrounded by outcropping rock. Associated species include hairy honeysuckle (Lonicera hispidula), fool's onion, trailing blackberry (Rubus ursinus), Gairdner's yampah (Perideridia gairdneri) and Falkland Island sedge (Carex macloviana). Woody shrubs such as saskatoon (Amelanchier alnifolia) and evergreen blackberry* (Rubus lacinatus), and alien invasive grasses and herbs such as common velvet-grass* and common vetch* (Vicia sativa), are in the process of encroaching onto the sites and may pose a serious threat.

3.4.4 Population size and trends

The Uplands Park population consists of two subpopulations–one near the central meadow, and one in the southwest corner of the park. The two subpopulations are separated by ~250 m. In 2005, the two patches contained an estimated 139 flowering individualss (M. Miller, pers. obs.). Although water-plantain buttercup has been known at Uplands Park since 1918, long-term population trends are unknown. Nevertheless, the population appears to be generally stable (Douglas and Illingworth 1998, CDC HERB Database 2004).

The population at Ballenas Island was first discovered only in 1996, when 15-20 plants were counted (CDC HERB Database 2004). In 2005, a total of 91 flowering individuals (and &gt;100 non-flowering individuals in various size classes) were enumerated in two different patches. This population also appears to be generally stable.

The best recent available information for water-plantain buttercup suggests a total population size of &lt;250 flowering individuals (Table 2). There is no indication of the size of the historical population in Canada.

Figure 4. Distribution of water-plantain buttercup in North America (left) and in British Columbia (right).
(Solid circle: extant range. Open circle: historical range.)
Figure 4. Distribution of water-plantain buttercup in North America (left) and in British Columbia (right). (Solid circle: extant range. Open circle: historical range.)

3.5 Rosy owl-clover

Common Name: Rosy owl-clover

Scientific Name: Orthocarpus bracteosus Benth.

Current status and most recent date of assessment: Endangered, May 2004

Reason for designation: An annual herb of vernal pools and damp depressions present at a single remaining location where population size fluctuates widely with low numbers that may be fewer than 100 plants a year. Expansion is limited due to lack of suitable habitats and apparent low dispersal abilities. The population is at risk from spread of nearby invasive exotic plants, from trampling due to hiker traffic and local maintenance activities related to the nearby communications site and consequences of possible oil spills occurring in the busy shipping lanes surrounding the island site.

Occurrence: BC

3.5.1 Description of the species

Rosy owl-clover is a small, annual, hemiparasitic herb from an erect stem 10–40 cm tall. Its leaves are alternate and unstalked. The flowers are rose-purple (occasionally white) and are grouped in a dense terminal spike among prominent bracts. The upper lip of the corolla is slender and slightly hooked at the apex; the lower lip is sac-shaped. The plant is minutely hairy and somewhat sticky-glandular. The lower leaves are lance-shaped, while the upper leaves have 3 to 5 spreading lobes. The bracts are green or purplish and are also lobed (Peck 1961, Douglas et al. 2000). In the field, rosy owl-clover may be confused with other owl-clovers in the genera Orthocarpus, Castilleja and Triphysaria, especially in the early, pre-flowering stages.

The species has no special economic or social significance in Canada.

3.5.2 Distribution and status

Rosy owl-clover ranges from Vancouver Island (vicinity of Victoria) to Oregon west of the Cascades, southward to Plumas County, CA (Fig. 5). In Washington, it is currently known from one meadow complex in Klickitat County. There are also historical records from San Juan and Whatcom Counties, WA. In British Columbia there is a single known occurrence, plus about nine historical localities. These are all restricted to the Saanich peninsula, on Vancouver Island.

Rosy owl-clover has a global conservation ranking of G3. It is ranked S1 in British Columbia and Washington and SNR (unranked) in California, Oregon, Maryland, and New York (NatureServe 2005). The Canadian extent of occurrence (EO) and total area of occupancy (AO) of rosy owl-clover is approximately 0.01 hectares. This represents &lt;1 percent of the species' total distribution.

3.5.3 Habitat

Across its range, rosy owl-clover is known from moist meadows and fields at low elevations (Peck 1961, Hitchcock and Cronquist 1973, Douglas et al. 2000). The single documented Canadian population occurs on a sloping vernal seep on Trial Island, a small Gulf Island adjacent to Victoria. The substrate consists of shallow (8–18 cmdeep) organic mineral soil lacking in pronounced structure, overtop of bedrock (Table 9). The soil is saturated during the winter and remains damp until June, becoming completely dry by late July. The dominant plant species include gumweed (Grindelia integrifolia), English plantain* (Plantago lanceolata), hairy cat's-ear* (Hypochaeris radicata), self-heal* (Prunella vulgaris) and rosy owl-clover. Less abundant species include the COSEWIC-endangered seaside trefoil (Lotus formosissimus), as well as yellow monkey-flower (Mimulus gutattus), sea thrift (Armeria maritima), red fescue (Festuca rubra), Nuttall's quillwort (Isoëtes nuttallii), Macoun's meadow-foam (Limnanthes macounii) and paintbrush owl-clover (Castilleja ambigua).

The vegetation is probably at a climax successional stage, as encroachment by native trees, shrubs and robust mesophytic herbs is prevented by the shallow soils, their lack of aeration during the extended period of winter saturation, and the pronounced summer drought. There is a limited degree of invasion by a number of aggressive nonnative species including Scotch broom* (Cytisus scoparius), English gorse* (Ulex europaeus), leather-leaved daphne* (Daphne laureola), common velvet-grass* (Holcus lanatus), English ivy* (Hedera helix), barren fescue* (Vulpia bromoides), and dovefoot geranium* (Geranium molle) (Fairbarns 2004).

Sites now extirpated in the vicinity of Victoria may have occurred on a variety of soils. Herbarium labels indicate that collections from Oak Bay, the Patricia Bay Highway, Elk Lake and Sidney came from "prairies", often on gravelly soil, while specimens from Blenkinsop Lake, Cedar Hill and one collection from Sidney were collected from peat meadows and ditches. This is consistent with habitat descriptions for populations in Washington State (Fairbarns 2004). However, more information is required on microsite attributes such as soil texture, soil depth, moisture levels, nutrient content, pH levels, length and timing of inundation, and disturbance regimes (Table 9).

3.5.4 Phenology and reproduction

At Trial Island, germination occurs from March to May, with flowering commencing in June (M. Fairbarns, unpubl. data). Each reproductive plant produces around 6 to 10 seed capsules, with each capsule producing approximately 7 seeds. Seed banking likely occurs, but this has not been confirmed. Plants begin to whither in July (earlier in drier microsites) as the soil dries, and are largely finished by August. Later-developing flowers and fruit tend to abort prematurely, presumably due to the onset of drought, suggesting that summer moisture stress in the vernal pool area may be depressing fecundity at this site (M. Fairbarns, unpubl. data).

3.5.5 Population size and trends

There are nine historical collections for rosy owl-clover in Canada, all in the Victoria area, but it is uncertain how many of these, in fact, represent distinct populations due to the vague location data (Fairbarns 2004). One population is currently extant on Trial Island. The earliest record from Trial Island (1976) did not include an estimate of population size. The total number of reproductive plants has varied in recent years from 40 to nearly 1000. In 2005, there were 210-230 flowering plants (M. Fairbarns, unpubl. data). Wide population fluctuations are typical in many other annual species (Harper 1977) and such fluctuations may obscure population trends--particularly if the increase in aboveground numbers occurs through seed bank depletion.

Figure 5. Distribution of rosy owl-clover in western North America (left) and in British Columbia (right).
(Solid circle: extant range. Open circles: historical range.)
Figure 5. Distribution of rosy owl-clover in western North America (left) and in British Columbia (right). (Solid circle: extant range. Open circles: historical range.)

3.6 Dwarf sandwort

Common Name: Dwarf sandwort

Scientific Name: Minuartia pusilla(S. Wats.) Mattf.

Current status and most recent date of assessment: Endangered, May 2004

Reason for designation: An annual ephemeral herb present at a single very small vernal seepage site along a rocky maritime headland in southern Vancouver Island highly disjunct from the nearest populations in southern Washington State. The maximum population size documented totals 20 plants with numbers likely fluctuating depending on precipitation patterns. Risks to the plants arise from the susceptibility of the single small population to stochastic events and on-going disturbance of the habitat by gulls, trampling by boaters and potentially from encroaching invasive plants.

Occurrence: BC

3.6.1 Description of the species

Dwarf sandwort is a small, annual herb from an erect stem 2 to 5 cm tall. The stems are solitary or branched, hairless, and have a glaucous tinge. The leaves are opposite and linear, 2 to 4 mmlong and &lt;0.5 mm wide. The inflorescence consists of 2 to 9 flowers in an open, leafy-bracted cyme that may comprise 4/5 the total height of the plant. The petals, when present, are elliptic and 1 to 2 mm long. The sepals are lance-shaped, 2 to 3 mm long, 3-nerved, and have long to abruptly sharp points. The capsules are egg-shaped, 1 to 2 mm long, and 3-valved. The seeds are purplish brown and about 0.5 mm long (Hitchcock and Cronquist 1973, Douglas et al. 1998b, Rabeler et al. 2005).

Dwarf sandwort has no special economic or social significance in Canada.

3.6.2 Distribution and status

The global range of dwarf sandwort extends from southwest British Columbia south to northern California and east to Idaho, Nevada and Utah (Douglas et al. 1998b, NatureServe 2005). In British Columbia, the species is known to occur at just a single location on the southern coast of Vancouver Island (Table 2, Fig. 6).

Dwarf sandwort has a global conservation ranking of G5T3T5. It is ranked S1 in British Columbia and SNR (unranked) in California, Idaho, Nevada, Oregon, Utah, and Washington (NatureServe 2005). The Canadian extent of occurrence (EO) and area of occupancy (AO) of dwarf sandwort are both approximately 10 . This represents &lt;1 percent of the species' total distribution.

3.6.3 Habitat

In British Columbia, the known habitat of dwarf sandwort consists of a sloping vernal seepage site on a rocky maritime headland in the Coastal Douglas-fir zone (Table 9). However, this may not be representative of the typical habitat, as elsewhere in its range the species is known from dry areas in sagebrush steppe, pine barrens, chaparral slopes, and dry rock cliffs (Hitchcock and Cronquist 1973, Hartman 1993, Rabeler et al. 2005). Thus, more information is required on microsite attributes such as soil texture, soil depth, moisture levels, nutrient content, pH levels, length and timing of inundation, and disturbance regimes (Table 9).

The substrate at the Rocky Point seepage site consists of shallow (3–7 cm deep) organic mineral soil with no pronounced structure, overlying bedrock (Table 9). The soil is saturated during the winter and remains damp through the spring, but dries completely by early summer, traits that may help discourage in-growth of larger herbaceous or woody species that might otherwise overgrow or outcompete dwarf sandwort. Associated native plants include slimleaf onion (Allium amplectens), erect pygmyweed (Crassula connata), dwarf owl-clover (Orthocarpus pusillus), Scouler's popcornflower (Plagiobothrys scouleri), and beach bluegrass (Poa confinis). The COSEWIC-candidate species winged water-starwort, and the COSEWIC-endangered species snake-root sanicle (Sanicula arctopoides) and seaside trefoil (Lotus formosissimus), are also found nearby.

3.6.4 Population size and trends

The first Canadian collection of dwarf sandwort was made at Rocky Point in 1977. Since then, recorded population size has fluctuated from 9 to a few hundred individuals (Penny and Costanzo 2004, M. Fairbarns, unpubl.data). In 2005, approximately 80 flowering plants (with 1 to 2 seed capsules per plant) were observed. It is possible the species maintains a dormant seed bank, in which case aboveground stem counts may not provide an accurate indication of true population size. However, this has not been confirmed. Long-term trends at this site (and elsewhere in British Columbia) are unknown.

Figure 6. Distribution of dwarf sandwort in North America (left) and in British Columbia (right).
(For the U.S. distribution, dots merely indicate states where found.)
Figure 6. Distribution of dwarf sandwort in North America (left) and in British Columbia (right). (For the U.S. distribution, dots merely indicate states where found.)


* used hereon to designate species non-native to British Columbia.
6Although not confirmed, there is a strong possibility that the Alberta and Saskatchewan records for tall woolly-heads actually represent misidentified specimens of P. brevissimus, and that what is referred to in the COSEWIC status report as the "Pacific population" of P. elatiormay therefore constitute the entire Canadian population (M. Fairbarns, pers. comm.). If so, the Endangered designation currently applied to the "Pacific population" would apply to the entire species in general..
7 Tall woolly-heads has been reported historically from as far west as Ucluelet on Vancouver Island (Macoun 1909). However, this record is unconfirmed and may be erroneous (M. Fairbarns, pers. comm. 2004).