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Montana Field Guide

Montana Field Guides

Mountain Bladder Fern - Cystopteris montana

Potential Species of Concern
Native Species

Global Rank: G5
State Rank: SH
(see State Rank Reason below)
State Threat Score: Unknown

Agency Status


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State Rank Reason (see State Rank above)
Reported for Montana from one collection in 1932 near Gunsight Pass in Glacier National Park.
General Description
Mountain Bladder Fern has delicate fronds arising singly from dark, cord-like, creeping rhizomes. The black, sparsely scaly petioles, 6-30 cm long, are longer than the triangular blades, which are 6-14 cm long and wide. The blade is pinnately divided into numerous pairs of leaflets, which become smaller towards the tip. The lower leaflets are again 2-3 times pinnately divided, while the upper leaflets are only pinnately lobed. The first downward pointing division of each of the 2 lowest leaflets is noticeably longer than the paired upward pointing divisions. Clusters of spores, or sori, are borne on veins just in from the edges on the undersides of the blades. Each sorus is partially contained in a whitish membranous pocket, or indusium.

Mature fronds in August.

Diagnostic Characteristics
The blades of C. fragilis are at least twice as long as they are wide. Gymnocarpium dryopteris has a triangular blade, but it is somewhat wider than it is long, and the sorus lacks an indusium. Dryopteris austriaca has blades that are over 20 cm long.

Range Comments
In MT known only from Flathead County; WA, MT, QC and disjunct in 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) Map Help and Descriptions
Relative Density



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

Moist rock ledges near or above timberline.

Ecological Systems Associated with this Species

  • 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?
    • Lellinger, D.B. 1985. A Field Manual of the Ferns and Fern-Allies of the United States and Canada. Smithsonian Inst. Press. Washington, D.C. B85LEL01PAUS
    • 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.
    • McLaughin, W. T. 1935. Notes on the flora of Glacier National Park, Montana. Rhodora 37:362-365.
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Citation for data on this website:
Mountain Bladder Fern — Cystopteris montana.  Montana Field Guide.  .  Retrieved on , from