Red water fern

Azolla filiculoides
Red water fern: Azolla filiculoides Red water fern: Azolla filiculoides

Common name:

Red water fern

Scientific name:

Azolla filiculoides (Azollaceae)

Alternative common names:

Watervaring (Afrikaans)

A free-floating perennial aquatic fern from tropical South American with horizontal stems up to 35mm long. It has a loose branching pattern. The leaves are 1-1,5mm long, almost circular in shape and are silvery-green turning reddish brown or purple in winter. 

Additional Info

  • Where does this species come from?

    Tropical South America.

    What is its invasive status in South Africa?

    Existing legislation: CARA 2002 – Category 1 NEMBA – Category 1b

    Where in South Africa is it a problem?

    This water weed is a problem throughout most wetlands in South Africa.

    How does it spread?

    Spores and detached plant segments.

    Why is it a problem?

    It can rapidly cover an open water surface and severely degrade aquatic ecosystems. These dense mats of red fern reduce light penetration and causes de-oxygenation, having a significant affect on organisms living below the water surface. This results in reduced quality of drinking water caused by bad odour, colour and turbidity.

    What does it look like?

    General description: A floating tiny-leafed aquatic plant which forms dense mats on the water surface, often turning red in colour. Bark: None. Leaves: Minute silvery-green leaves turning reddish brown or purple in winter. Flowers: None Fruit/seeds: Fruiting bodies are minute, and appear in October to February.

    Does the plant have any uses?

    Used mostly as an aquarium plant and sometimes as a water feature ornamental.

    Plant me instead alternatives

    Cape pond weed (Aponogeton distachyos), small yellow water lily (Nymphoides thunbergiana).