Red Water Fern
Azolla filiculoides
NEMBA category
English: Red Water Fern, Mosquito Fern, Water Velvet
This small floating aquatic fern forms dense mats on water. It is native to the Americas and has spread widely throughout the world by a variety of mechanisms, of which man has become the most significant.
It grows rapidly, easily out-competing indigenous vegetation. Decaying root and leaf matter below a mat of Azolla filiculoides, coupled with the lack of light penetration, creates an anaerobic environment which can reduce the quality of drinking water and make survival for other organisms in the water impossible.
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Origins: North and South America
Overall Appearance:
Azolla filiculoides is a small, free-floating aquatic fern that forms dense mats on the surface of still or slow-moving water bodies. It has a feathery appearance with delicate, overlapping leaves.
Leaves:
Leaves are small, overlapping, and typically green, although they may turn reddish-brown in winter.
Flowers:
Flowers are inconspicuous and rarely produced.
Fruits:
Not typically produced.
Seeds:
Seed production is rare.
Soil Type:
Not applicable. This plant floats on the water surface.
Aspect:
Prefers calm, still water bodies with ample sunlight.
Uses:
Historically used as a green manure in rice paddies.
Can be used as an ornamental plant in aquariums.
Problem Provinces:
Widespread throughout South Africa, particularly in wetlands, dams, and slow-moving rivers.
Note:
Azolla filiculoides is a highly invasive aquatic weed in South Africa.
It forms dense mats that block sunlight from reaching the water below, inhibiting the growth of submerged plants and reducing oxygen levels.
This can lead to fish kills and disrupt aquatic ecosystems.
It can also impede water flow and clog irrigation channels.
Friendly alternatives:
Common name
Scientific Name
Plant type:
Plant type
Plant family:
Plant family (derivation)