Fauna
Plant · GBIF taxon 2870583

Water Lettuce

Pistia stratiotes

Also known as Water Cabbage, Nile Cabbage, Shellflower

Water lettuce drifts in buoyant, velvety rosettes across calm freshwater bodies, reproducing rapidly via connected stolons to blanket open water in dense green mats. Submerged feathery root systems absorb copious nutrients and offer refuge to small aquatic organisms, while the thick leaf canopy shades out submerged vegetation and depletes dissolved oxygen. Though popular in ornamental ponds and aquariums, escaped populations severely disrupt water transport and provide prime microhabitats for disease-bearing mosquitoes.

AquaticFloatingInvasive
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Least ConcernConservation statusIUCN Red List categoriesLCNTVUENCREWEXLeast ConcernRed List categories, explained →
Key facts
Diet & prey
  • Photoautotrophic, absorbs dissolved aquatic nutrients directly through submerged roots
Predators
  • Water Lettuce Weevil
  • Apple Snail
  • Grass Carp
ThreatsFreezing temperatures, herbicide applications, and biological control weevils
HabitatsSlow-moving rivers, canals, ponds, lakes, marshes, and ditches in tropical and subtropical zones
Life spanPerennial (or annual in regions subject to winter frosts)
Classification
  1. OrderAlismatales
  2. FamilyAraceae
  3. GenusPistia
  4. SpeciesPistia stratiotes
Range & activity
Range data is not available yet.
Safe observation
Interaction riskHigh
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is high
Contains microscopic calcium oxalate crystals; toxic to humans, dogs, and cats if chewed or swallowed.
Why it is dangerous
Plant tissues contain insoluble calcium oxalate raphides that pierce oral tissues, causing intense burning, swelling, and digestive distress in pets and humans.
How to recognize a risky encounter
Look for stemless, ridged, soft-hairy light green leaves arranged like a head of open lettuce floating freely on water.
What to do
Do not taste or ingest; wash hands after clearing large mats and keep away from grazing pets.
Responsible observation
  • Disposal Check: Compost or desiccate thinned plants on dry land away from runoff to prevent wild escapes.
  • Mosquito Control: Agitate water or stock safe native fish to suppress larvae sheltering among the roots.
  • Aquarium Pruning: Thin crowded rosettes regularly to preserve light penetration for underwater flora.
Related species
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