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

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

Introduction to Vascular Plants

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.

General:
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.

Leaves:
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

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration Source: The Illustrated Flora of British Columbia

Origin Status	Provincial Status	BC List (Red Blue List)	COSEWIC
Native	S3	Blue	T (Nov 2008)

BC Ministry of Environment: BC Species and Ecosystems Explorer.

Two other Azolla species occur in BC: A. filiculoides and A. caroliniana, both of which are likely introduced from eastern North America. Azolla caroliniana is distinguished from the other two species by its smaller size (less than 1 cm in diameter), its dichotomously-branched form throughout, and its leaves that are scarcely, or not at all, overlapping. Azolla mexicana can be distinguished from A. filiculoides by its less imbricate leaf form, smaller size (< 3 cm vs. 2 to 6 cm), many crosswalls (vs. no crosswalls) on the hooked hairs of microspore masses, and the megaspores shallowly pitted (vs. net-veined) in the basal region (Brunton 1983; Douglas et al. 2000).

Source: British Columbia Conservation Data Centre

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