Priority: - Prevent
Tags: Aquatic | EDRR
Identification and Reproduction
- Water lettuce is an aquatic plant that floats above the surface of the water with roots hanging submerged in the water.
- This plant does not have a stem, rather leaves are gathered in a rosette.
- Rosettes are about 10 cm wide and 6 cm tall.
- Leaves are light green, soft, succulent, wavy margins with parallel running veins and can reach up to 14cm in length.
- Flowers are found in the middle of the rosette.
- Roots hang below and appear feathery.
- Water lettuce can reproduce from seeds or vegetatively.
- It will produce clones from short, brittle stolons.
- Stolons can spread up to 60 cm in length.
Habitat & Ecology
- This plant is the most productive freshwater aquatic plant in the world.
- Often regarded as a free-floating aquatic plant, water lettuce can still survive in moist soil.
- It is sensitive to frost and is often restricted to tropical and sub-tropical regions.
- It thrives in waters that are high in nutrient content, notably waters that are contaminated with sewage or fertilizers.
- Can block irrigation canals and reservoirs.
- Dense mats can clog hydro-electricity turbines and halt energy production.
- Dense mats will alter the hydrological properties of ecosystems.
- In extreme cases water lettuce can grow over the waterbody and block any gas exchange at the air-water interface. This reduces oxygen levels in the water and will kill fish and other organisms.
- Large infestations will also out-shade native aquatic species.
- Provide a good breeding habitat for mosquitoes. Eggs are laid under the leaves and larvae attach to the plant roots.
Prevention is a high priority for this plant.
- Do not plant or purchase this plant to put in your pond or water garden.
- Never release unwanted plants into natural waterbodies.
- Learn to identify this plant and avoid traveling infested sites.
- Always clean, drain, and dry aquatic equipment like boats or canoes before transferring from one body of water to another.
- Small infestations should be controlled to prevent the subsequent spread.
- Harvesters can also be used to remove plants.
- Control will be long-term and will need to be repeated.
For more details check out the Invasive Species Compendium datasheet on Pistia stratiotes (water lettuce).
Header photo (Σ64).