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Dwarf woolly-heads - Psilocarphus brevissimus
State Rank Reason (see State Rank above)
DRAFT: Requesting feedback on the 2026 revised rank, factors, and State Rank Reason outlined below and in the Conservation Status Rank Report.
Psilocarphus brevissimus is rare in Montana, known from just over a dozen sites primarily in northwest and north-central Montana. Data on the populations are limited and generally 20-30 years old. Several populations were documented as containing "thousands" of plants. Significant and imminent threats to the populations are not known though current data are lacking. The species appears to be vulnerable but not at a high risk of extirpation in the state.
Surveys to document population sizes and extent, habitat quality and potential or existing threats are needed for all populations. Surveys of potentially suitable habitat may locate additional populations.
General Description
Dwarf Woolly-heads is a low annual with erect to prostrate, branched stems that are up to 5 cm tall. The alternate, lance-shaped leaves are 5-25 mm long, and the foliage is densely covered with white, tangled hairs. Minute flowers are borne in globose, woolly heads that are partially hidden among the upper leaves. Each flower and seed in the head is enclosed by a long-hairy bract that is ca. 3 mm long. A pappus is lacking.
Phenology
Mature fruit June-early August.
Diagnostic Characteristics
Gnaphalium paulstre, a woolly annual of vernally moist habitats, and Filago arvensis, an introduced annual, may appear to be similar, but each has a pappus on top.
Species Range
Montana Range
Range Descriptions
Native
Range Comments
Eastern Washington to Baja California east to western Montana, eastern Wyoming and northern Utah, with disjunct populations in Chile and Argentina.
Observations in Montana Natural Heritage Program Database
Number of Observations: 25
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Habitat
Drying mud of ponds and other vernally wet soil in the valleys and on the plains.
National Vegetation Classification System Groups Associated with this Species
Wetland and Riparian
Wet Meadow and Marsh
Stewardship Responsibility
Threats or Limiting Factors
STATE THREAT SCORE REASON
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).
References
- Literature Cited AboveLegend:
View Online Publication
MTNHP Threat Assessment. 2021. State Threat Score Assignment and Assessment of Reported Threats from 2006 to 2021 for State-listed Vascular Plants. Botany Program, Montana Natural Heritage Program, Helena, Montana.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- Cronquist, A. 1950. A review of the genus Psilocarphus. Research Studies of the State College of Washington 28(2):71-89.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
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