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

Habit Plants green to yellowish green or dark red, with 2 growth stages; plants fertile only in mature stage, generally in late spring.

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


on upper leaf lobes strictly unicellular.


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

Azolla filiculoides

Habitat Stagnant and slow-moving waters.
from FNA
AZ; CA; OR; WA; BC; Mexico; Central America; Europe; ne Asia; s Africa; Pacific Islands in Hawaii
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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.)

Source FNA vol. 2, p. 341.
Parent taxa Azollaceae > Azolla
Sibling taxa
A. caroliniana, A. mexicana
Name authority Lamarck: in Lamarck et al., Encycl. 1: 343. (1783)
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