THIS week, Hillcrest Conservancy, takes a look at the Water lettace, as part of its series of articles on alien invasive plants, to help the community to identify and eradicate them from their gardens.
The Water lettuce’s scientific name is Pistia stratiotes (Araceae) but it is also known as the Nile cabbage, Nile lettuce, shell flower, water cabbage, water fern and Waterslaai (Afrikaans).
Description: The free-floating, aquatic perennial plant seldom exceeds 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 to May, but occasionally throughout the year in warm tropical climates, it produces small, green capsules.
The leaves are poisonous and known to cause intense internal irritation.
Where does the species come from?
This species was originally from South America (Brazil).
What is its invasive status in South Africa?
It is a Category 1b plant and must, therefore, be removed from your garden.
Where in South Africa is it a problem?
KwaZulu-Natal, Eastern Cape and Mpumalanga.
How does it spread?
It forms dense mats which completely cover a water surface. It invades dams, pans and slow-moving rivers in subtropical regions.
Why is it a problem?
These dense mats clog waterways and irrigation equipment, reduce waterflow, impede navigation, fishing and other recreational activities and provides a breeding place for mosquitoes and bilharzia-carrying snails. Should this species escape into our dams we would be faced with a serious problem.
Does the plant have any uses?
It is used as an aqua ornament.
Do you want to receive news alerts via WhatsApp? Send us a WhatsApp message (not an sms) with your name and surname to 060 532 5409.
You can also join the conversation on Facebook, Twitter and Instagram.
