Flora of North America species comparison

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Azolla filiculoides

Azolla caroliniana

duckweed fern, large mosquito fern, mosquito fern, Pacific mosquito fern, water fern

Carolina mosquito fern, eastern mosquito fern
Habit Plants green to yellowish green or dark red, with 2 growth stages; plants fertile only in mature stage, generally in late spring. Plants dark green or with margins of bright crimson or whole plants dark red, free-floating or forming multilayer mat to 4 cm thick under good conditions; plants infrequently fertile.
Stems

prostrate when immature, 1–3 cm, internodes elongate to 5 mm, becoming nearly erect to 5 cm or more when mature and crowded.

prostrate, 0.5–1 cm.
Hairs

on upper leaf lobes strictly unicellular.

Megaspores

warty with raised angular bumps, each with a tangle of filaments.

without raised angular bumps or pits, densely and uniformly covered with tangled filaments.
Largest

hairs on upper leaf lobe near stem with 2 or more cells;

broad pedicel cell often 1/2 or more height of hair, apical cell curved, with tip nearly parallel to leaf surface.

Azolla filiculoides

Azolla caroliniana
Habitat Stagnant and slow-moving waters. Stagnant or slow-moving water in ponds, lakes, marshess, swamps, and streams.
Distribution
from FNA
AZ; CA; OR; WA; BC; Mexico; Central America; Europe; ne Asia; s Africa; Pacific Islands in Hawaii
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; CT; DE; FL; GA; IL; IN; KS; KY; LA; MA; MD; MI; MO; NC; NE; NJ; NY; OH; OK; PA; SC; SD; TN; TX; VA; WV; ON; Mexico; South America; West Indies; Europe; Asia
[WildflowerSearch map]
Discussion

Azolla filiculoides is cold tolerant, surviving even in fragmented parts under thin ice. It usually reaches a climax population in late spring, becomes fertile, collapses, and is replaced by other more heat-tolerant aquatics such as Lemna spp. Hybrids between this species (male) and A. microphylla Kaulfuss (female), a species of Central America, South America, and the West Indies, have been reported (Do V. C. et al. 1989). V. M. Bates and E. T. Browne (1981) reported A. filiculoides from Georgia, far removed from its main range in western North America. The most likely explanation is that the plants represent escapes from horticulture.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

The sporophyte of Azolla caroliniana commonly survives throughout the year in temperate areas (with hard frosts and prolonged ice cover). It is the best adapted of all species for subsistence on mud. Azolla caroliniana is rarely collected with sporocarps.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 2, p. 341. FNA vol. 2, p. 341.
Parent taxa Azollaceae > Azolla Azollaceae > Azolla
Sibling taxa
A. caroliniana, A. mexicana
A. filiculoides, A. mexicana
Name authority Lamarck: in Lamarck et al., Encycl. 1: 343. (1783) Willdenow: Sp. Pl. 5(1): 541. (1810)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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