E-Flora BC: Electronic Atlas of the Flora of British Columbia

Azolla mexicana Schltdl. & Cham. ex C. Presl
Mexican mosquito fern (Mexican mosquitofern)
Azollaceae (Azolla family)

Introduction to Vascular Plants

© Brian Klinkenberg  Email the photographer   (Photo ID #4283)

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Distribution of Azolla mexicana
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Mexican mosquitofern is a tiny floating aquatic fern that is found in stillwater areas of lakes, oxbows and ponds. In the US, it is found in AR, AZ, CA, CO, IA, IL, KS, MN, MO, NE, NM, NV, OK, OR, TX, UT, WA, WI (USDA 2010). In Canada, this species is found only in British Columbia where it is reported from the Shuswap, Sicamous, Salmon Arm, Little Fort, and Vernon areas It was first collected in BC by John Macoun from Sicamous in 1889, and was then reported by him from Salmon Arm in 1890 (COSEWIC 2008).

Today, ten populations of this species are known in British Columbia, where it occurs in quiet pools in creeks, oxbow ponds, sheltered lake edges and small bays, and wet depressions. Mexican mosquitofern is easily spotted from a distance in mid- to late summer when plants turn a bright red on wetland surfaces. It may occur in small floating patches, or extensively cover the water surfaces.

Species Information

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Delicate aquatic ferns floating on water surface, plants usually 1-1.5 cm long, pinnately branched from a central axis, dichotomously branched only at the periphery of the plant; fronds overlapping like shingles, often densely so.
The upper lobes usually 0.7-0.9 mm long.Sporocarps Borne on floating lobes; hooked hairs with many cross-walls; megaspores shallowly pitted at the base.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Sloughs and pools in the montane zone; rare in SC BC, S to WI, IL, MO, TX, NM and CA.

Source: The Illustrated Flora of British Columbia

Additional Notes

Mexican mosquitofern is easily spotted from a distance in mid- to late summer, when plants turns a bright red.


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References