Water Hyacinth & Water Lettuce

Harmful Impacts

In the wild, invasive water lettuce and water hyacinth create thick mats on water surfaces that reduce oxygen levels, block sunlight, and prevent growth of submerged vegetation. Mats interfere with recreation and can have a negative effect on fish and other aquatic species.


Both of these free-floating, aquatic invasive plants are on the state of Michigan’s watch list. It is important to prevent, detect, and quickly control watch list species because if left unchecked they can spread rapidly with many negative impacts to the environment and economy.


Local Efforts

Water lettuce was discovered in the Clinton River Spillway and McBride Drain in 2020. In 2021, the CISMA surveyed almost 140 acres within the Clinton River watershed and removed over 3,300 pounds of invasive water lettuce and water hyacinth from Miller Drain in Macomb Township.

How You Can Help

  • If you use these in water gardens or aquariums, they should never be released into wild waterways.

    • Dispose of unwanted plants in the trash.

  • Enthusiasts should provide a physical barrier between ponds and wild waters to prevent accidental spread during flood events.

  • Clean boats, boat trailers, fishing equipment, waders, and other gear to prevent spread.

  • Report observances to the Midwest Invasive Species Information Network or notify your local CISMA.


Water hyacinth

  • Distinctive air bladders that keep leaves afloat

  • Rounded, leathery leaves arranged in whorls of 6-10

  • 14-day flowering cycle produced lavender flowers with central yellow fleck


Water lettuce

  • Resembles an open head of lettuce

  • Leaves are thick and ridged, light green, & have short, white hairs

  • Many feathery roots dangle under the rosette


Fish and other live beings from water gardens should also never be released into water bodies. If you find your water garden with an overabundance of fish in the fall contact a local retailer, find another water gardener that has space for additional fish, or trade with another hobbyist.

If you suspect a non-native plant or animal in the wild, please report the occurrence to the Midwest Invasive Species Information Network (MISIN) or contact the Lake St. Clair CISMA directly at CISMA@macombgov.org. For more tips, visit this MSU Extension Water Garden Care page.

Water Garden Tips

Caring for water gardens helps to reduce future problems in both your ponds, water gardens, and wild waters!

Reducing Invasive Pet and Plant Escapes (RIPPLE) is crucial to keep in mind when removing unwanted plants and fish. Some of the most popular water garden plants sold, including water lettuce, water hyacinth and European water clover, are not native to Michigan and should never be released into waterways, lakes and streams. Outside of cultivation, these plants can create thick mats that reduce oxygen levels, block sunlight, and prevent growth of submerged vegetation. Mats interfere with recreation and can have a negative effect on fish and other aquatic species in an infested area. Unwanted plants should be placed in a sealed bag in the trash.