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MONTANA FIELD GUIDE™

MONTANA FIELD GUIDE™

Large-fruited Kobresia - Kobresia sibirica
Other Names:  Kobresia macrocarpa, Carex borealipolaris

Species of Concern
Native Species

Global Rank: G5
State Rank: S2
(see State Rank Reason below)
State Threat Score: Unknown
C-value: 8


Agency Status
USFWS:
USFS:
BLM:


 





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. Kobresia sibirica is rare in Montana, where it is known from a few occurrences in alpine tundra on the Beartooth plateau. Occurrences are in remote areas with the known populations occurring within designated wilderness areas or research natural areas. The remote habitat limits the potential for negative impacts, and no significant and widespread threats to the species are known besides potential impacts associated with climate change. Population levels are imprecisely known though appear to be relatively small, and trends are unknown though populations have likely been relatively stable in the recent past or experienced only minor declines. The known occurrences have not been surveyed since the 1990's. Climate change may negatively affect this species over the next several decades. However, the timing and magnitude of potential impacts are largely unknown. Although climate change is listed as a potential threat to the species, it does not affect the overall threat rank or scoring, or the final subnational rank. Survey and monitoring data are needed to be able to more precisely determine population levels, assess condition and for assessing population trends. Surveys in potentially suitable habitat are likely to document additional occurrences.
Large-fruited Kobresia (Kobresia sibirica) Conservation Status Summary
State Rank: S2
Review Date = 07/23/2026
See the complete Conservation Status Rank Report
How we calculate Conservation Status Ranks
CC BY NC
 
General Description
Stems 5–15 cm. Leaves inrolled, ca. 0.5 mm wide; basal bladeless. Inflorescence 1–2 cm long, a solitary spike; bracts 5–6 mm long. Spikelets: upper male, 1-flowered; lower bisexual, 1- to 3-flowered. Perigynia light brown, 3.5–5 mm long. Achenes 2.5–4 mm long (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Phenology
Fruit matures in late July-August.

Diagnostic Characteristics
This species could be confused with Kobresia bellardii, Carex elynoides, or Carex scirpoidea, which have narrower spikes, usually less than 4 mm wide. The former two species occur in drier habitats.

Species Range
Montana Range Range Descriptions
Range in Montana
CC BY NC
Native
 


Range Comments
Circumpolar south to CO (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 6
(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
Moist tundra, solifluction slopes, and gravelly lake shores in the alpine zone.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see here

National Vegetation Classification System Groups Associated with this Species
Alpine
Alpine - Vegetated
Wetland and Riparian
Alpine Riparian and Wetland
Wet Meadow and Marsh


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.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Fertig, W. and M. Bynum. 1994. Biological report on the proposed Twin Lakes Research Natural Area. Unpublished report to the Shoshone National Forest. Wyoming Natural Diversity Database, Laramie, Wyoming. 33 pp. plus appendices.
    • 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.
  • Web Search Engines for Articles on "Large-fruited Kobresia"
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Citation for data on this website:
Large-fruited Kobresia — Kobresia sibirica.  MONTANA FIELD GUIDE™.  .  Retrieved on , from