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Montana Field Guide

Montana Field Guides

Big-leaf Sedge - Carex amplifolia

Potential Species of Concern

Global Rank: G4
State Rank: SH
* (see State Rank Reason below)

Agency Status
MNPS Threat Rank:
C-value: 5

External Links

State Rank Reason (see State Rank above)
Only known in Montana from one collection in the northwestern part of the state. A revisit of the site is needed.
  • Details on Status Ranking and Review
    Big-leaf Sedge (Carex amplifolia) Conservation Status Review
    Review Date =
General Description
Rhizomatous. Stems erect, 50–100 cm, reddish at the base, tufted. Leaves basal and cauline; sheaths hispidulous; blades 1–2 cm wide. Inflorescence of 4 to 8 overlapping, pedunculate spikes; the lowest bract greater than the inflorescence. Spikes ascending, 3–10 cm long, linear; the uppermost male, otherwise female. Perigynia ascending, green to brown, ovoid, glabrous, 3–4 mm long including the 1–2 mm long beak. Female scales acute to mucronate, reddish brown with a hyaline tip and a light midstripe, longer or shorter than the perigynia. Achene 3-sided, filling the perigynium (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Fruits mature in July-August.

Diagnostic Characteristics
The leaves of this species are much broader than either C. lasiocarpa or C. lanuginosa. Carex amplifolia could be confused with C. utriculata, but the perigynia of the latter are 4-7 mm long. A hand lens and technical manual should be used for positive identification.

Species Range

Range Comments
BC south to CA, ID and MT; collected in Sanders County (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX). Also disjunct in NM (Kartesz in prep. 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 7

(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)


Ecological Systems Associated with this Species

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Citation for data on this website:
Big-leaf Sedge — Carex amplifolia.  Montana Field Guide.  .  Retrieved on , from