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U.S. Forest Service

Plant of the Week

USDA Plants distribution map for the species. Range map of Azolla filiculoides. USDA PLANTS Database.

Pacific Mosquitofern (Azolla filiculoides) Pacific Mosquitofern (Azolla filiculoides).

Pacific Mosquitofern (Azolla filiculoides)

By Robinson Sudan

Physical Characteristics: At some times of the year, the scaly leaves of Azolla filiculoides can appear pink or red with changes in sunlight and temperature. This free-floating water fern is approximately three centimeters long. Freely branching, it can easily break off parts to reproduce vegetatively. It derives its common name from its propensity to form dense mats on still water that are said to be so thick as to prevent mosquito larvae from hatching.

Growing Conditions and Distribution: Native to many parts of the Old and New Worlds, A. filiculoides has nevertheless become either invasive or a nuisance species in many parts of its current range. Its speedy vegetative reproduction, propensity to form mats, and the ease with which it can be transported or spread by vertebrates makes it a good competitor and sometimes difficult to control.

Conservation Status: Not threatened.

Pollinator Information: As with all ferns, Azolla filiculoides does not reproduce using pollen, but with spores.

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