Kariba weed

Kariba weed

Salvinia molesta (Salviniaceae)

Common Name:

Kariba weed

Scientific Name:

Salvinia molesta (Salviniaceae)

Alternative common names:

Salvinia, African pyle, water fern (English); watervaring (Afrikaans)


An aquatic, mat-forming, free-floating fern with horizontal stems up to 25cm long. Green to yellow-green oval leaves form in pairs with dense upper surface cover of hairs. Feathery, root-like leaves hang down in the water

Additional Information

Where does this species come from?

Brazil in 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?

Western and Eastern Cape, KwaZulu-Natal, Gauteng, Mpumalanga and Limpopo

How does it spread?

Spreads only vegetatively by fragmentation

Why is it a problem?

Forms dense mats up to 50 cm thick which completely cover a water surface. The mats clog waterways and irrigation equipment, reduce waterflow, impede navigation, fishing and other recreational activities, provide a breeding place for mosquitoes and bilharzia-carrying snails. Dense mats reduce light penetration, reduce oxygen levels and result in poor water quality. Dense mats threaten indigenous aquatic plant and animal life

What does it look like?

General description: A green, mat-forming water weed with leaves covered in dense hairs.
Leaves: Green to yellow-green oval leaves in pairs with dense upper surface cover of hairs
Flowers: None
Fruit/seeds: None

Does the plant have any uses?


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