Lindley’s false silverpuffs (Uropappus lindleyi) COSEWIC assessment and status report: chapter 2

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COSEWIC Executive Summary

Species information

Lindley’s false silverpuffs (Uropappus lindleyi, formerly named Microseris lindleyi), a member of the aster family, is approximately 10-70 cm tall and usually has a simple stem growing from a slender taproot. The long leaves at the base of the plant are linear and pointed at the tip. The stem leaves are usually linear and occur on the bottom half of the stems. The flowering stems emerge from the base or from the axils of the stem leaves. The solitary, terminal flowering heads have strap-shaped, yellow flowers.

Genetic studies of the genus Microseris(=Uropappus) have discovered numerous DNA and enzyme differences between M. lindleyi and other members of the genus resulting, in part, in the recognition of the genus Uropappus. Variation within Uropappus lindleyi material from the U.S. was not detected; no genetic studies have been conducted using Canadian material of the species.

Distribution

Lindley’s false silverpuffs ranges from southwestern British Columbia disjunctly to Idaho and central Washington and south to Oregon, Utah, Texas, New Mexico, Arizona and California. A historic occurrence is known in the San Juan Islands of northwestern Washington. In Canada, Lindley’s false silverpuffsis known only from the Gulf Islands in southwestern British Columbia. Less than one percent of the species’ total range occurs in Canada. The current Extent of Occurrence in Canada is approximately 150 km². The actual area of habitat occupied is about 0.01 km² but the Area of Occupancy, based on a 1x1 km or 2x2 km grid for the five localities, is a maximum of 20 km².

Habitat

Lindley’s false silverpuffs populations in British Columbia are found in, or near, Garry oak (Quercus garryana) and associated ecosystems in the dry Coastal Douglas-fir zone of southeastern Vancouver Island and adjacent Gulf Islands. This area has a relatively warm and dry Mediterranean climate. The speciesoccurs in a number of different habitats ranging from sandstone cliffs and steep grassy slopes to xeric deciduous or evergreen forests. There is no specific information on the trends of Lindley’s false silverpuffshabitats on southeastern Vancouver Island or the adjacent Gulf Islands although they almost certainly share the same threats as Garry oak ecosystems, including agricultural development, urbanization and invasion by aggressive alien weeds.

Biology

Lindley’s false silverpuffs is an annual species, with flowering typically observed in late-April to mid-May in British Columbia and seed production occurring in from mid-May to June. Compared to similar species in the genus Microseris, Lindley’s false silverpuffs is characterized by such features such as being self-pollinated and having smaller flowers and fewer scales (bracts) surrounding the flower heads. The bristle-tipped pappus scales attached to the top of the fruitlets could attach to bird feathers, and may possibly enable long-distance dispersal. Most seeds, however, are likely dispersed locally by wind and gravity.

Population sizes and trends

There are five extant locations in Canada where Lindley’s false silverpuffshas been collected since 1974. One additional population was recorded in 1998, and is probably extirpated as a result of housing development. Population sizes range from approximately 20 to 1200 plants on areas of less than 1 m² to 1 ha. The most recent survey of the populations indicates that there are probably about 2000 individuals in Canada. The potential for immigration from the species’ main range is unlikely. Even locally, exchange of seeds or pollen probably occurs only rarely due to lack of effective dispersal vectors.

Limiting factors and threats

The most immediate threat to Lindley’s false silverpuffsin British Columbia is habitat destruction through housing development on private property. Almost all populations occur on valuable, private ocean view properties. Habitat destruction has also resulted in increased fragmentation of populations. In addition, much of the remaining habitat suitable for Lindley’s false silverpuffshas been heavily altered due to invasion by introduced species.

Special significance of the species

In California,Lindley’s false silverpuffs seeds are collected from the wild and sold in at least one native plant nursery; other cultural, medicinal or spiritual uses are unknown. Since the Canadian population represents the northern extent of the species’ range, it may be of evolutionary and ecological significance. Genetic study of Microseris (the genus within which Lindley’s false silverpuffs was formerly included) indicates that Lindley’s false silverpuffs (=M. lindleyi) has distinct differences from other members of the genus. Consequently, the recent reclassification places Lindley’s false silverpuffs in the genus Uropappus, consisting of a single species (U. lindleyi).

Existing protection or other status designations

Globally, Lindley’s false silverpuffshas a rank of G5, indicating that it is considered "frequent to common to very common; demonstrably secure and essentially ineradicable under present conditions". The species is tracked as a rare species outside of British Columbia only by Utah, with a rank of S1 (critically imperiled) in the state or province because of extreme rarity or because of some factor(s) making it especially vulnerable to extirpation). Since the species is restricted to British Columbia in Canada, it has a national rank of N1 (critically imperiled in the nation because of extreme rarity or because of some factor(s) making it especially vulnerable to extirpation).Provincially, Lindley’s false silverpuffs is ranked by the British Columbia Conservation Data Centre as S1 and appears on the British Columbia Ministry of Environment red list.

COSEWIC History

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

COSEWIC Mandate

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

COSEWIC Membership

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

Definitions (2008)

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)^Footnotea

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)^Footnoteb

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

Data Deficient (DD)^Footnotec

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.