Hero Image

Invasive Freshwater Plants and Algae

Brazillian Egeria

  • Scientific Name

    Egeria densa - Visit ITIS for full scientific classification. 

  • Description


    • Submerged waterweed forms dense mats.
    • Has long stems, single white flowers (3 petals) at water surface.
    • Leaves are smooth and narrow, with teeth on edges and no stalks, placed in groups along stems.
    • Looks like Hydrilla, except that upper and middle leaves are 1/2" - 1 1/2" long.
    • It looks larger and leafier than Hydrilla.
    • Often has 4 leaves per group.
    • The similar Elodea often has 3 leaves per group. 
  • Habitat
    • Still or slow-moving, freshwater habitats with high nutrient levels.
    • Grows best under low light (~100 lux), tolerates turbidity and brief time under ice. 
  • Invasion Pathways and Distribution
    • Introduced from eastern South America as an aquarium plant.
    • Can infest when it is discarded from an aquarium into freshwater habitats.
    • Occurs in several areas of California and it is expected to spread to new areas. 
  • Life History
    • In U.S. plants only produce pollen-bearing flowers.
    • Can grow and infest from pieces. 
  • Impacts
    • Aggressively invades new areas, displacing other plants and changing aquatic ecosystems.
    • Forms dense, submerged mats that reduce water flow, interfere with boating and fishing, and clog pumps needed for irrigation, water supply, and flood control.
    • California State Parks - Division of Boating and Waterways conducts a control program in the Sacramento-San Joaquin Delta. 
  • References and Useful Links

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