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Porsild's Draba - Draba porsildii
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.
Draba porsildii is known in Montana from less than a dozen sites, primarily from the Beartooth Plateau with an outlying site in the Madison Range. Population sizes are unknown as are trends. However, populations are likely relatively stable or have experienced only minor declines as the species' alpine habitat is remote and largely intact. Threats to the species are generally unknown, though shifts in climate may negatively impact the species, and it is rated as "Extremely Vulnerable" to climate change as part of an analysis using the CCVI.
Surveys are needed to document population sizes and extent of the known occurrences. Monitoring of a subset of populations is needed to be able to determine potential population trends.
General Description
Porsild's Draba is a low perennial herb with few to many leafless stems that are 1-6 cm high and which arise from basal leaf rosettes that, in turn, arise from the ends of a simple or branched rootcrown. The lance-shaped leaves are 3-12 mm long, have entire margins, and are covered with branched hairs. The stalked flowers are borne at the tops of the stems in nearly flat-topped inflorescences. Each flower has 4 separate sepals, 4 separate, white petals, and 4 long and 2 short stamens. The style is ca. 0.2 mm long. The glabrous, narrowly elliptic capsules are 4-8 mm long and are borne on ascending stalks that are 1-2 mm long.
Phenology
Flowering in July, fruiting in July-August.
Diagnostic Characteristics
There are many similar-appearing species of Draba in our area. A technical manual and hand lens or microscope are required for positive identification. Draba lonchocarpa, a more common white-flowered species, has capsules that are usually greater than 8 mm long.
Species Range
Montana Range
Range Descriptions
Native
Range Comments
YT south to CO. In MT known only from the Beartooth Range in Carbon County (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)
Observations in Montana Natural Heritage Program Database
Number of Observations: 12
(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
Moist, gravelly open soil in the alpine zone.
National Vegetation Classification System Groups Associated with this Species
Alpine
Alpine - Sparse and Barren
Alpine - Vegetated
Wetland and Riparian
Alpine Riparian and Wetland
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- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
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?- Lesica, P. 1993. Vegetation and flora of the Line Creek Plateau area, Carbon County, Montana. Unpublished report to USDA Forest Service, Intermountain Research Station. Montana Natural Heritage Program, Helena, Montana. 30 pp.
- 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.
- Mulligan, G.A. 1976. The genus Draba in Canada and Alaska: key and summary. Canadian Journal of Botany 54:1386-1393.
- Web Search Engines for Articles on "Porsild's Draba"
