Water Lettuce

Invasive Species

Common Name

Water Lettuce

Scientific Name

Pistia Stratiotes


  • Water Lettuce Is A Free Floating Plant That Has An Appearance Very Much Like An Open Head Of Lettuce
  • The Leaves Are Covered In Very Fine Hairs And Arranged In A Spiral Pattern From The Center Of The Plant
  • A Sizable Number Of Unbranched Feathery Roots Up To 80cm Long Are Submersed In Water Beneath The Leaves Of The Plant
  • The Fruit Inside The Plant Is A Greenish Berry 5-10 In Diameter
  • The Flowers Of Water Lettuce Are Up To 1.5cm Long Hidden In The Center Of The Plant Among The Leaf Bases. The Flowers Are Whitish-Green In Colour
  • The Water Lettuce Can Grow Up To 15cm Tall And 30cm Wide

Where Does The Species Originate From Originally?

  • It Is Believed That The Water Lettuce Is Native To Africa, Though There Is No Consensus On Where It Originated From On The Continent

Where can it be found in canada?

  • In Ontario, It Has Been Found In Ponds Connected To The Rideau Canal Near Ottawa And In Welland Canal In The Niagara Region, Lake St. Clair And Its Tributaries, Bronte Creek In Oakville And Beaches East Of Toronto

when was the species introduced to canada?

  • The Water Plant Was Introduced To Canada In The 19th Century

Who Or What introduced the organisms to its new habitat?

  • The Water Lettuce May Have Arrived In Ballast Water And Explorer's Sailing Ships
  • The Plant Adapts To Life In Ponds, Lakes And Quiet Areas Of Rivers And Streams But Cannot Withstand Salt Water. Also, Not Being Able To Tolerate Cold Temperatures

what is the ecological damage cause by the organism?

  • As The Plant Dies And Decomposes, It Removes Oxygen From The Water Which Can Disrupt Fish Communties
  • It Can Completely Cover Water Bodies Disrupting All Life On The Water
  • It Clogs Waterways Preventing River Travel And Blocks Irrigation Canals
  • It Affects Hydro-Electricity Production As Its Vast Mats Clog The Turbines

What Is Its Role In Its Environment?

  • They Can Be Used In Fish Ponds As They Provide Shelter. The Hanging Roots Offer Protection To Spawn And Smaller Fishes
  • They Play A Role In Preventing Algal Blooms By Using Up Nutrients In The Water
  • Submerged Portions Of All Aquatic Plants Provide Habitats For Many Mirco And Marco Invertebrates. These Invertebrates In Turn Are Used As Food By Fish And Other Wildlife Species ( Amphibians, Reptiles, Ducks, Etc.)
  • Their Decomposition By Bacteria And Fungi Provides Food Which Are Called "Detritus" For Many Aquatic Invertebrates, Water Lettuce Has No Known Direct Food Value To Wildlife And Is Considered A Pest Species

Attempts At Capture

  • Avoid Infested Areas Or Reduce Your Speed When Boating Near Water Lettuce Infestations
  • Inspect Your Boat, Trailer And Equipment After Each Use. Remove All Plants, Animals And Mud Before Moving To A New Waterbody

Human Health Impacts Of The Species

  • Children, Adults And Livestock May Be In Danger Of Drowning If They Become Entangled In The Roots Of A Heavy Infestation
  • Water Lettuce Mats May Also Create A Place For Mosquitoes That Are Vectors Of Ross River Fever And Diseases


  • If You Find A Water Lettuce, Your Reward Will Be $150 With A 6 Inch Mini Water Lettuce To Grow

Contact Us :)

If You Find Water Lettuce Or Other Invasive Species In The Wild, Please Contact The Toll-Free Invading Species Hotline At 1-800-563-7711


By: callista griffiths