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Montana Field Guide

Montana Field Guides

Thin-flowered Sedge - Carex tenuiflora

Species of Concern
Native Species

Global Rank: G5
State Rank: S2
(see State Rank Reason below)
State Threat Score: No Known Threats

Agency Status


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State Rank Reason (see State Rank above)
Rare in Montana, where it is currently known from only one site in Glacier National Park. The potential for negative impacts to the occurrence are minimal.
General Description
Caespitose. Stems weak, often prostrate, 20–50 cm. Leaves basal and cauline; blades ca. 1 mm wide. Inflorescence of 2 to 4 sessile, aggregated spikes; lowest bract inconspicuous. Spikes 4–6 mm long, all similar, bisexual; female flowers above. Perigynia spreading to ascending, pale green, narrowly ovoid, 3–3.5 mm long with an inconspicuous beak; stigmas 2. Female scales hyaline to tan with a green midvein, shorter than the perigynia. Achene 2-sided, filling the perigynium (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Fruit mature in July-August.

Diagnostic Characteristics
Carex tenuiflora could be confused with two other more common peatland sedges: C. interior and C. canescens. The former has lance-shaped perigynia, and both have scales that are only half the length of the perigynia. A hand lens or microscope will be needed to observe these characters.

Species Range
Montana Range Range Descriptions


Range Comments
Circumboreal south to BC, MT, CO; collected once in Flathead 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: 3

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Wet, organic soil of Sphagnum-dominated fens in the montane zone.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

Threats or Limiting Factors
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).

  • 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?
    • 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 "Thin-flowered Sedge"
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Citation for data on this website:
Thin-flowered Sedge — Carex tenuiflora.  Montana Field Guide.  .  Retrieved on , from