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Montana Field Guide

Montana Field Guides

Prairie Sedge - Carex prairea

Species of Concern
Native Species

Global Rank: G5
State Rank: S3
(see State Rank Reason below)
State Threat Score: No Known Threats
CCVI: Highly Vulnerable
C-value: 9

Agency Status


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State Rank Reason (see State Rank above)
Rare in Montana, where it is currently known from a small area in the northwest corner of the state. The potential for negative impacts to the popoulations appears to be low.
General Description
Densely caespitose. Stems erect, 30–60 cm. Leaves: basal and cauline; cauline sheaths coppery opposite the blades that are 1–3 mm wide. Inflorescence elongate, of several, sessile, ascending spikes, overlapping above, separate and sometimes branched below; lowest bract inconspicuous. Spikes 3–6 mm long, all similar, male flowers above, female below or all female. Perigynia ascending, lanceolate, tan to brown, glabrous, serrulate-margined, 3–4 mm tapered to the flattened, grooved beak, 1.5–2 mm long; stigmas 2. Female scales brown lanceolate, concealing the perigynia. Achene 2-sided, filling the perigynium (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Fruiting mid-July through August.

Diagnostic Characteristics
Carex prairea is somewhat intermediate between C. diandra and C. cusickii; distinguished from the former by having leaf sheaths that are copper colored inside at the mouth, more open flowering heads, and dull perigynia. Carex cusickii also has copper colored sheaths and open heads but has wider leaves and brownish-black perigynia. A hand lens or microscope and technical key are needed for positive identification.

Species Range
Montana Range Range Descriptions


Range Comments
YT to NL south to MT, IL, VA. Known from Lincoln 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: 21

(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)

Rich fen with alluvium derived from calcareous glacial till in the valley 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 "Prairie Sedge"
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Citation for data on this website:
Prairie Sedge — Carex prairea.  Montana Field Guide.  .  Retrieved on , from