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Thick-leaf Whitlow-grass - Draba crassa
State Rank Reason (see State Rank above)
Draba crassa occurs in Montana at the northern edge of the species' range. Plants are found at at least twelve sites within four mountain ranges in the state. Population counts and trends are unknown. However, populations are presumed to be relatively stable or experiencing only minor declines because the species' alpine habitat is remote and largely intact. Threats to the species are generally unknown, though shifts in climate may negatively impact Draba crassa.
Surveys that bring forth current data on population parameters, habitat conditions, mapping, and potential threats are needed. Monitoring at a subset of populations is greatly needed to assess population trends, and more accurately determine its state conservation status rank in the state.
General Description
Perennial from a simple or branched caudex clothed in old leaf bases. Stems simple, 4–12 cm. Basal leaves petiolate, oblanceolate, 2–5 cm long, entire. Stem leaves several, lanceolate, sessile. Vestiture of simple and forked hairs on the stem and sparse cilia on leaf margins. Petals yellow, 3–5 mm long. Fruit ascending, 5–9 × 3–5 mm, glabrous, often twisted; style 0.3–1 mm long; lower pedicels 2–8 mm long (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Species Range
Montana Range
Range Descriptions
Native
Range Comments
Regional endemic of south-central Montana, western Wyoming, northeastern Utah, and Colorado.
Observations in Montana Natural Heritage Program Database
Number of Observations: 21
(Click on the following maps and charts to see full sized version)
Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Habitat
Rocky areas in the alpine particularly on cool, shady sites.
Ecological Communities Associated with this Species
Alpine
Alpine - Sparse and Barren
Alpine - Vegetated
Wetland and Riparian
Alpine Riparian and Wetland
Stewardship Responsibility
Threats or Limiting Factors
Reliable threats to Thick-leaf Whitlow-grass have not been reported though climate change poses a potential risk to the state's populations. The MTNHP conducted a species-level assessment using the Climate Change Vulnerability Index (CCVI) in 2021, which resulted in an Extremely Vulnerable rating to climate change. Climate change including increased ambient temperatures, decreased snowpacks, and increased frequencies and severities of drought could have negative impacts on this species; however, field-based data on the timing and magnitude are not available.
The report of significant, negative impacts at one site from invasive plants is questionable because alpine environments rarely have invasive plants.
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?- Aho, Ken Andrew. 2006. Alpine and Cliff Ecosystems in the North-Central Rocky Mountains. Ph.D. Dissertation. Bozeman, Montana: Montana State University. 343 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.
- Rollins, R. C. 1993. The Cruciferae of Continental North America: systematics of the mustard family from the Arctic to Panama. Stanford University Press, Stanford, California. 976 pp.
- Web Search Engines for Articles on "Thick-leaf Whitlow-grass"
