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Invasive Freshwater Plants and Algae

Giant Salvinia

  • Scientific Name

    Salvinia molesta - Visit ITIS for full scientific classification. 

  • Description


    • Floating mats, no flowers (fern), leaf tops fuzzy with tiny, egg-beater shaped hairs.
    • In open water, leaves are oval, flat, 1/3" to 1/2"wide.
    • When in dense mats, leaves are 2-lobed, folded, crowded and are 1" to 2 1/2" wide if unfolded to examine. 
  • Habitat
    • Still or slow-moving, warm, freshwater habitats with high nutrient levels.
    • Tolerates low salinity and occasional frost. 
  • Invasion Pathways and Distribution
    • Introduced from tropical South America.
    • Found worldwide in tropical areas.
    • Can be used to remove excess nutrients and other pollution from water and, when dried, as mulch.
    • It is spread by wind, water motion, floods, boating, fishing and discarding plants from ponds and aquariums into waterways.
    • In California it occurs along the Colorado River, in canals in Riverside and Imperial Counties, and in San Luis Obispo County. 
  • Life History
    • This aquatic fern rarely produces spores.
    • Instead, it breaks into pieces of stem that spread vegetatively.
    • It can double its biomass in 2-3 days when conditions are right. 
  • Impacts
    • Dense mats up to 20" thick cover open water, outcompete native plants and animals, increase stagnation and risks of flooding, reduce water quality, and interfere with navigation and recreation.
  • References and Useful Links

    For references by category and links to other useful AIS sites see our LEARN MORE page.