Rosy owl-clover (Orthocarpus bracteosus) COSEWIC assessment and status report: chapter 2

Executive Summary

Rosy Owl-clover
Orthocarpus bracteosus

Species Information

Rosy owl-clover (Orthocarpus bracteosus) is a small, annual herb. Its leaves are alternate and unstalked. The tube-shaped rose-purple flowers are grouped in a dense terminal spike among prominent bracts. A white-flowered form is occasionally encountered, usually among purple-flowered plants.

Distribution

Rosy owl-clover occurs in western North America, mainly from Vancouver Island south to Oregon west of the Cascades, and southward east of the Cascades to northern California. In Canada, it has been found in the vicinity of Victoria, British Columbia. Populations in the adjacent islands of Washington State have disappeared.

Habitat

Rosy owl-clover favours moist vernal pools and depressions that are moist in the winter and dry out in the summer. It is found with a variety of small herbs, in the absence of robust herbs, shrubs or trees.

Biology

Rosy owl-clover is an annual plant that germinates, grows, flowers and produces seed in the spring/early summer, and then withers and dies. Most seeds are probably dispersed in the vicinity of the parent plant, as the seeds lack adaptations for long-distance dispersal. It forms root-connections with a number of other species of plants, from which it obtains water and nutrients but it also contains chlorophyll and is autotrophic.

Population Sizes and Trends

A maximum of nine historic records are known. Eight of these presumably different populations dating from 1887 to 1954 are now extirpated. A single population remains on Trial Island, near Victoria, B.C. This population has fluctuated from 40 to about 940 individuals between 1998 and 2002 but the plants have not spread to occupy new habitat, even in favourable years.

Limiting Factors and Threats

Urbanization in the vicinity of Victoria, B.C. has eliminated many former populations and continues to pose a threat to suitable, unoccupied habitat. Invasions by aggressive, alien weeds have reduced the capability of habitats to support rosy owl-clover and threaten the remaining population on Trial Island. Foot traffic associated with the Canada Coast Guard lighthouse on Trial Island and incidental use by boaters also threaten the current population. Marine pollution presents a constant threat as this species occurs near sea level along a busy oil tanker route.

Special Significance of the Species

The British Columbia population of O. bracteosus is about 300 km disjunct from the northern extent of their main range in California, Oregon and southern Washington State.

Existing Protection or Other Status Designations

The Trial Island population occurs in Trial Island Ecological Reserve within metres of its boundary with a commercial communications lease. The plants, like all species within an ecological reserve, are legally protected under the Protected Areas of British Columbia Act. The ecological reserve lacks a management plan to address management of the species and employees rarely visit the site. Rosy owl-clover is red-listed in British Columbia and has a provincial status of S1 (critically imperiled).

COSEWIC History

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

COSEWIC Mandate

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

COSEWIC Membership

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

Definitions (after May 2004)

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 it 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)Footnote1
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)Footnote2
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)Footnote3
A wildlife species for which there is inadequate information to make a direct, or indirect, assessment of its risk of extinction.

 

Canadian Wildlife Service

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

 

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