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Stalked-pod Locoweed - Oxytropis podocarpa
State Rank Reason (see State Rank above)
Oxytropis podocarpa is rare in Montana, where it is known from a few occurrences from the Rocky Mountain Front north to Glacier National Park. The state population level appears to be at least 3,000 plants, to perhaps more than 10,000. Most observation data is more than 35 years old. Population trend data is lacking. However, populations are presumed to be relatively stable because their habitat is remote, largely intact, and afforded some protections where designated as wilderness or national park. Threats have not been reported though climate change poses a potential risk to the state's populations.
Revisits to known occurrences, at specified intervals, are greatly needed to collect data on population parameters, habitat conditions, and potential threats. Monitoring at a subset of occurrences is necessary to track population trends. Additional surveys into areas of potentially suitable habitat are also needed to better assess the state's distribution.
General Description
Stalked-pod Crazyweed is a perennial that usually forms small, dense cushions. Its naked stems are erect or prostrate and up to 7 cm long. The basal leaves are 2-5 cm long and pinnately divided into 9-27 narrowly lance-shaped leaflets. The herbage is covered with stiff, silvery hairs. The 1-2 purple flowers resemble pea flowers and are held erect at the top of the stem. The corolla is 12-17 mm long, and the tubular calyx is purplish and 2/3 the length of the corolla. The papery, inflated pod is 15-25 mm long and ovoid in outline.
Phenology
Flowering in June, fruiting late June-August.
Diagnostic Characteristics
This is our only purple-flowered Oxytropis with fewer than 4 flowers. Species of alpine Astragalus have leafy stems.
Species Range
Montana Range
Range Descriptions
Native
Range Comments
AB to CO; Baffin Island to NL (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations: 14
(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
Gravelly ridges and slopes, often on limestone, 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
Ecology
POLLINATORS The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap:
Bombus appositus,
Bombus bifarius,
Bombus centralis,
Bombus fervidus,
Bombus flavifrons,
Bombus melanopygus,
Bombus nevadensis,
Bombus rufocinctus,
Bombus sylvicola,
Bombus occidentalis,
Bombus insularis, and
Bombus kirbiellus (Macior 1974, Bauer 1983, Shaw and Taylor 1986, Williams et al. 2014, Miller-Struttmann and Galen 2014).
Stewardship Responsibility
Threats or Limiting Factors
Threats to Stalked-pod Locoweed 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 a Highly 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.
References
- Literature Cited AboveLegend:
View Online Publication- Bauer, P.J. 1983. Bumblebee pollination relationships on the Beartooth Plateau tundra of Southern Montana. American Journal of Botany. 70(1): 134-144.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
Macior, L.M. 1974. Pollination ecology of the Front Range of the Colorado Rocky Mountains. Melanderia 15: 1-59.- Miller-Struttmann, N.E. and C. Galen. 2014. High-altitude multi-taskers: bumble bee food plant use broadens along an altitudinal productivity gradient. Oecologia 176:1033-1045.
- 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.
- Shaw, D.C. and R.J. Taylor.1986. Pollination ecology of an alpine fell-field community in the North Cascades. Northwest Science 60:21-31.
- Williams, P., R. Thorp, L. Richardson, and S. Colla. 2014. Bumble Bees of North America. Princeton, NJ: Princeton University Press. 208 p.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- 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.
- Web Search Engines for Articles on "Stalked-pod Locoweed"
