Dwarf Woolly-heads Southern Mountain population
Scientific Name: Psilocarphus brevissimus
Other/Previous Names: Dwarf Woolly-heads
Taxonomy Group: Vascular Plants
Range: British Columbia
Last COSEWIC Assessment: April 2006
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered
Image of Dwarf Woolly-heads
Two varieties of Dwarf Woolly-heads are recognized: the typical Psilocarphus brevissimus var. brevissimus and P. brevissimus var. multiflorus. Since the species is represented in Canada only by the brevissimus variety, the name “Dwarf Woolly-heads” is used here without the variety being specified.
Dwarf Woolly-heads is a small, woolly annual with short, opposite leaves. The upper leaves usually surpass the flower clusters, or heads. The flower heads are copiously woolly and inconspicuous like the rest of the plant. Each head is lobed, and each lobe contains a few central male flowers surrounded by anywhere between 8 and 80 female flowers. Each female flower is partly enclosed by a minute sac composed of tiny specialized leaves, or bracts. Although the heads appear to be growing at the end of shoots, they are actually located in the forks of inconspicuous branches. Unlike the flower heads of most other members of the Aster family, the heads of this species are not surrounded by rings of small bracts.
Distribution and Population
The range of Dwarf Woolly-heads extends from south-central British Columbia south to Montana and Utah in the western United States to Baja California, Mexico. It also occurs in Chile and Argentina. In Canada, Dwarf Woolly-heads is known from only the Similkameen Valley south of Princeton in south-central British Columbia and from southeastern Alberta and southwestern Saskatchewan. The Southern Mountain population (British Columbia) and the Prairie population (Alberta and Saskatchewan) are separated by a distance of over 500 km and several mountain ranges. In British Columbia, Dwarf Woolly-heads occurs at three known sites. Like all annual plant populations of vernal pools and temporary ponds, the Southern Mountain population fluctuates greatly from year to year, depending on rainfall and flooding. It may have as few as 700 mature individuals in “trough” years and perhaps as many as 2 million in “peak” years. It is therefore difficult to predict long-term trends in this population.
Dwarf Woolly-heads occurs in calcareous clay soils in vernal pools in large forest openings dominated by two other flowering plants: Scouler’s popcornflower and close-flowered knotweed. It is also found in shallow, temporarily flooded depressions and along lakes and ponds, in the same type of soils, wet in spring but dried out and compacted in summer. Some of the potential habitat has been lost over the past century because of agricultural development and invasion by exotic grasses and shrubs. The amount of suitable habitat fluctuates greatly depending on the degree of spring flooding.
There are very few data on the biology of this species. However, it is known that Dwarf Woolly-heads flowers and fruits in mid- to late summer in British Columbia. The lack of structures to aid in wind or animal dispersal of pollen suggests that the species likely reproduces by self-pollination, meaning its flowers are fertilized by its own pollen. Dwarf Woolly-heads fruits when the pool in which it is growing dries out. The seeds, which are dispersed in the late fall, lack structures to aid long-distance dispersal. Some seeds may be dispersed by small mammals that feed on them, while others may be carried long distances in mud on the feet of shorebirds and waterfowl that frequent vernal pools. The seeds germinate during the early summer, but the plant continues to develop even as the surrounding uplands dry out. The ability to tolerate high moisture levels in winter and very low moisture levels in summer enables this species to grow where many other plants would succumb to environmental stress.
The most imminent threat to the Southern Mountain population is its small area of occupancy. In fact, this population is particularly vulnerable and even susceptible to extirpation in British Columbia because there are very few localities and they are restricted to small areas of suitable habitat. The primary threat to this population comes from habitat alteration due to changes in grazing and hydrology practices. Two Dwarf Woolly-heads sites occur on private lands within the Agricultural Land Reserve, in which agriculture is recognized as the primary land use. Some of the activities permitted in the land reserve could be inconsistent with the habitat requirements of the species. The recreational use of all-terrain vehicles observed in the immediate area of these sites represents another definite threat. The vehicles could alter the environment radically enough that it will become inhospitable for this species and suitable for invasive exotic plant species. Weed control activities are also a potential threat to this annual plant. The chemicals used to control invasive noxious weeds on rangelands or highway verges, for example, are marginally specific and may kill Dwarf Woolly-heads. Climate change may pose a significant threat to the species by reducing the frequency of flooding in suitable sites.
Federal ProtectionThe Dwarf Woolly-heads, Southern Mountain population, is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
Dwarf Woolly-heads is not protected under any provincial legislation in British Columbia.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Multi-species Recovery Strategy for the Princeton Landscape, including Dwarf Woolly-heads (Psilocarphus brevissimus) Southern Mountain Population, Slender Collomia (Collomia tenella), and Stoloniferous Pussytoes (Antennaria flagellaris) in Canada
Status Final posting on SAR registry
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
14 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (2 record(s) found.)
- Response Statements (2 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- Orders (4 record(s) found.)
- COSEWIC Annual Reports (2 record(s) found.)
- Consultation Documents (2 record(s) found.)
COSEWIC Status Reports
Multi-species Recovery Strategy for the Princeton Landscape, including Dwarf Woolly-heads (Psilocarphus brevissimus) Southern Mountain Population, Slender Collomia (Collomia tenella), and Stoloniferous Pussytoes (Antennaria flagellaris) in Canada (2013)The federal Minister of the Environment is the competent minister for the recovery of the Dwarf Woolly-heads - Southern Mountain Population, Slender Collomia, and Stoloniferous Pussytoes and has prepared the federal component of this multi-species recovery strategy as per section 37 of SARA. It has been prepared in cooperation the Province of British Columbia. SARA section 44 allows the Minister to adopt all or part of an existing plan for the species if it meets the requirements under the Species at Risk Act for content. Environment Canada has adopted the British Columbia recovery strategy for these plant species and prepared a federal addition to meet the requirements of SARA.
COSEWIC Annual Reports
COSEWIC Annual Report - 2004 (2004)2004 Annual Report to the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
COSEWIC Annual Report - 2006 (2006)2006 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
- Date modified: