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Montana Field Guide

Montana Field Guides

Pacific Mosquito Fern - Azolla filiculoides
Other Names:  Large Mosquito Fern, Pacific Mosquitofern

Native Species

Global Rank: G5
State Rank: SNR
(see State Rank Reason below)

Agency Status


External Links

State Rank Reason (see State Rank above)
Previously and incorrectly reported as A. mexicana in Montana.
General Description
Tiny, floating, mat-forming, aquatic annual. Stems tightly branched with simple roots. Leaves emersed, alternate, overlapping, sessile with 2 ovate lobes <1 mm long; upper lobe green or red, covered with white, flake-like hairs; lower lobe smaller and floating. Sporocarps dimorphic, obovoid, apparently in lower leaf axils; megasporocarps with 1 spore < 0.5 mm long; microsporocarps ca. 0.1 mm long with numerous spores clustered in small masses bearing hooked hairs (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range
Montana Range Range Descriptions


Range Comments
BC to CA, AZ, NM, TX, Mexico. Collected in Ravalli 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: 9

(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)


  • Literature Cited AboveLegend:   View Online Publication
    • Douglas, G.W., D. Meidinger, and J. Pojar, editors. 2000. The Illustrated Flora of British Columbia. Volume 5. Dicotyledons (Salicaceae through Zygophyllaceae) and Pteridophytes. British Columbia Ministry of Environment, Lands and Parks and British Columbia Ministry of Forests, Victoria.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
  • Web Search Engines for Articles on "Pacific Mosquito Fern"
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Citation for data on this website:
Pacific Mosquito Fern — Azolla filiculoides.  Montana Field Guide.  .  Retrieved on , from