Dense water weed

Egeria densa
Dense water weed: Egeria densa Dense water weed: Egeria densa

Common name:

Dense water weed

Scientific name:

Egeria densa (Hydrocharitaceae)

Alternative common names:

Waterpes (Afrikaans)

A submerged aquatic plant with slender stems up to 3m long. Green, finely serrated leaves 15-30mm long in whorls of 4-5, sometimes 3-8. Yellow or cream flowers appear on long stalks about 20mm above the water surface. This aquatic plant invades still or slow-moving water in lakes and ponds.

Additional Info

  • Where does this species come from?

    South America (Argentina, south-eastern Brazil and Uruguay)

    What is its invasive status in South Africa?

    Existing legislation: CARA 2002 – Category 1 Proposed legislation: NEMBA – Category 1b

    Where in South Africa is it a problem?

    KwaZulu-Natal and the Western Cape.

    How does it spread?

    Spreads by fragmentation of the plant parts and dormant tubers.

    Why is it a problem?

    This aquatic invasive plant can negatively impact an aquatic ecosystem. It displaces native plants, blocks light needed for photosynthesis, reduces the amount of dissolved oxygen in the water and deposits silt and organic matter several times the normal rate.

    What does it look like?

    General description: Submerged aquatic plant with slender stems up to 3m long. Leaves: Green; margins finely serrated, but serrations not visible with the naked eye, leaf tip ends in one spine cell. Flowers: Yellow or cream, three-petalled; flowers about 15mm across, long-stalked and protrudes 20mm above the water surface.

    Does the plant have any uses?

    Used as an ornamental and for aquarium trade.