Tall bugbane (Cimicifuga elata) COSEWIC assessment and status report: chapter 2

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Executive Summary

Description

Cimicifuga elata (Tall Bugbane) is a perennial, large-leafed understorey plant that stands 1 to 2 m tall. Stems are branched above and leaves are bi-ternate with 9 to 17, cordate to ovate, often palmate leaflets, which are usually 3-lobed. This species has a dark, tuberous, horizontal rhizome. The inflorescence is a simple to compound raceme with 50 to 900 small, white, closely-crowded flowers. Individual flowers are radially symmetrical and apetalous, and sepals are white or pinkish, falling off at once. Fruits are follicles, 9 to 12 mm long, subsessile, appearing singly in the upper flowers, but in two’s, and rarely, three’s in the lower ones of the raceme. Follicles each contain approximately 10 red to purple-brown seeds.

Distribution

Cimicifuga elata occurs from southwestern Oregon and western Washington north to southwestern British Columbia. In British Columbia, C. elata is only found sporadically in the Chilliwack River valley. Cimicifuga elata occurrences are all west of the Coast-Cascade Mountains in British Columbia and Washington, but within the mountain range in southwestern Oregon.

Habitat

Cimicifuga elata grows in shady, moist, mixed, mature western red cedar-hemlock and Douglas-fir, but also in predominately deciduous stands. The deciduous component is extremely important, providing the perfect balance of shade and light, and moisture retention. Common associated species include Rubus parviflorus, Oploplopanax horridus, Acer circinatum, Dryopteris expansa, Tolmeia menziesii, Sambucus racemosa, Circaea alpina, and Asarum caudatum.

Biology

There is no information available on the biology of Cimicifuga elata in British Columbia, however, studies related to pollination ecology, and population genetic structure have been conducted in Washington and Oregon. There have also been studies on the presence of active compounds of pharmacological use in species of Cimicifuga. Percentage germination is low and seeds are heavy with no special dispersal mechanism in C. elata.

Population Sizes and Trends

There are seven extant, recently verified, 1 historic and 2 unverified populations of Cimicifuga elata in the Chilliwack River valley. Populations are relatively small, ranging from a single plant to 63 plants. Cimicifuga elata has likely been extirpated from the Liumchen mountain site, which has been extensively converted to young forest. In addition, only a single plant was observed on Cheam Mountain, also an area extensively clearcut several years ago; the first observation at this site reported several plants in a clearcut. Other than this association with forest practises, no other population trends are known.

Limiting Factors and Threats

Cimicifuga elata has both intrinsic biological limitations, and an uncertain future under current logging regimes in the Pacific Northwest. Cimicifuga elata occurs in small populations that are sporadically distributed over the landscape, is relatively much less attractive to pollinators than other flowering plants, and lacks any specialized seed dispersal mechanism. Extremely small populations exist which are susceptible to low genetic diversity, and imminent extirpation. In addition, the increasingly fragmented landscapes of the forests of the Pacific Northwest threaten the continued persistence of this species. Populations of C. elata are notably absent from young 15-30 year-old managed stands, and re-colonization into these sights may be unlikely due to the low reproductive success and the poor dispersal ability of this species.

Existing Protection

There is currently no legislation that specifically protects Cimicifuga elata in Canada. However, the British Columbia Ministry of Environment, Lands, & Parks has recognized rare vascular plants as 'wildlife,' and Cimicifuga elata is considered 'red-listed,’ or rare and threatened/endangered. None of the populations of C. elata occur in protected areas, with the exception of two small British Columbia Forest Service reserves on Mt. Vedder, one a small ‘wildlife tree patch, ’ and the other, a ‘visual landscape’ reserve.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of wild species, subspecies, varieties, and nationally significant populations that are considered to be at risk in Canada. Designations are made on all native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fish, lepidopterans, molluscs, vascular plants, lichens, and mosses.

COSEWIC comprises representatives from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership), three nonjurisdictional members and the co-chairs of the species specialist groups. The committee meets to consider status reports on candidate species.

Species

Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X)

A species that no longer exists.

Extirpated (XT)

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

Endangered (E)

A species facing imminent extirpation or extinction.

Threatened (T)

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

Special Concern (SC)*

A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)*

A species that has been evaluated and found to be not at risk.

Data Deficient (DD)***

A species for which there is insufficient scientific information to support status designation.

* 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.

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.

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