Native to North America, this annual aquatic fern is also known as fairy moss and is a member of the Salviniaceae, a small family of about 20 ferns. The plants are about an inch tall and are usually found floating on the surface of still or slowly moving water where they form a mat. Prostate, branched stems carry feather like roots suspended in the water and green to gray-green fronds that are scale-like, bilobed, and carried in two rows. The upper frond floats on the surface of the water while the lower frond is submerged below it. In bright sunlight or cool temperatures the fronds become rusty red. Mosquito fern grows rapidly and is attractive in ponds and water gardens but can become a nuisance. With the aid of the symbiotic blue-green algae, Anabaena azollae, the fronds are able to fix nitrogen and so have been used in rice paddies as fertilizer. The genus name, Azolla, may be from the Greek words azo meaning to dry and allyo meaning to kill referring the the fact that the plant is killed by drought. Alternatively, the name may be derived from a word used by the local population where the plant was collected. The specific epithet, caroliniana, in the Latinized form of Carolina referring to the states where it is native.
Type: Aquatic annual
Size: 1″ H and spreading
Light: Full sun to partial shade
Hardiness: Zones 7-11
Care: Remove unwanted plants with a net.
Pests and Diseases: None of significance
Propagation: Move plantlets to desired site
Companion Plants: Cattail, lizard’s tail, white mountain violet
Outstanding Selections: None available
Photo Credit: Kurt Stuber Wikipedia