Water lettuce

Pistia stratiotes
Water lettuce: Pistia stratiotes Water lettuce: Pistia stratiotes

Common name:

Water lettuce

Scientific name:

Pistia stratiotes (Araceae)

Alternative common names:

Nile cabbage, Nile lettuce, shell flower, water cabbage, water fern (English), Waterslaai (Afrikaans)

A free-floating, aquatic perennial plant seldom exceeding 150-200mm in diameter. The plants consist of a rosette of leaves and a tuft of long, fibrous roots beneath and it resembles floating lettuces. The leaves are pale yellow-green, narrower at the base and round, straight or notched at their tips, ribbed, with many longitudinal veins radiating from the base. The leaves are softly hairy on both surfaces. Small pale green or white flowers appear from February-May, but occasionally throughout the year in warm tropical climates and it produces small, green capsules. The leaves are poisonous and known to cause intense internal irritation. It invades dams, pans and slow-moving rivers in subtropical regions.

Additional Info

  • Where does this species come from?

    South America (Brazil)

    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?

    KwaZulu-Natal, Eastern Cape and Mpumalanga

    How does it spread?

    Spreads and reproduces by seeds and rhizomes

    Why is it a problem?

    Forms dense mats which completely cover a water surface. The mats clog waterways and irrigation equipment, reduce waterflow, impede navigation, fishing and other recreational activities, provides a breeding place for mosquitoes and bilharzia-carrying snails

    What does it look like?

    General description: A free-floating, aquatic perennial plant seldom exceeding 150-200mm in diameter. The plants consist of a rosette of leaves and a tuft of long, fibrous roots beneath and resemble floating lettuces. Leaves: Pale yellow-green, narrower at the base and round, straight or notched at their tips, ribbed, with many longitudinal veins radiating from the base. The leaves are softly hairy on both surfaces. Flowers: Small pale green or white flowers appearing from February-May, but occasionally throughout the year in warm tropical climates. Fruit/Seeds: Produces small, green capsules

    Does the plant have any uses?

    Used as an aquatic ornament

    Plant me instead alternatives

    Small yellow waterlily (Nymphoides thunbergiana), Cape pond weed (Aponogeton distachyos)