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Brazilian Waterweed Elodea densa

Previously known as:

  • Egeria densa
This plant is an invasive species in North Carolina
Description

Brazilian Waterweed is an invasive perennial aquatic plant in the Hydrocharitaceae family found in freshwater ecosystems, including ditches, lakes, ponds, rivers, and streams. Native from Eastern Bolivia to Southeastern/Southern Brazil, Northeastern Argentina, and Uruguay, importers brought Brazilian Waterweed to the United States in the 1890s for use in aquariums. Plants dumped from aquariums were the initial source of infestations. In addition to invading most of the United States, Brazilian Waterweed is now found in much of Central America, Europe, and parts of Africa, Asia, Australia, and New Zealand. In North Carolina, it infests freshwater habitats in the coastal plain, piedmont, and mountains.

Brazilian Waterweed roots in water up to 20 feet deep, and grows underwater, with small, white, three-petaled flowers appearing above the surface sporadically from spring through fall. Whorls of as few as 3 to as many as 8 small (1 by .25 inch) simple, oblong green leaves with finely serrated edges occur on plant shoots. These shoots have circular stems, each with 6 to 12 double nodes—two nodes separated by a very short internode. These double nodes can produce adventitious roots, as well as buds and branches. Invasive spread does not occur from sexual reproduction, but from new plants forming from shoot fragments containing at least one double node.

Brazilian Waterweed can create dense colonies that block the sun, excluding other plants, degrading fish habitat, and interfering with recreational use, such as fishing and swimming. It is sometimes mistaken for another invasive, Hydrilla, which has more prominently serrated leaves and produces underground tubers.

Insects, Diseases, and Other Plant Problems: No significant problems. Listed as invasive by the NC Invasive Plant Council and in many other states.

See this plant in the following landscape:
Cultivars / Varieties:
Tags:
#invasive#full sun tolerant#white flowers#weedy#high maintenance#fast growing#aggressive#aquariums#shade tolerant#waterweed#aquatic weed
 
Cultivars / Varieties:
Tags:
#invasive#full sun tolerant#white flowers#weedy#high maintenance#fast growing#aggressive#aquariums#shade tolerant#waterweed#aquatic weed
  • Attributes:
    Genus:
    Elodea
    Species:
    densa
    Family:
    Hydrocharitaceae
    Life Cycle:
    Perennial
    Country Or Region Of Origin:
    E. Bolivia to SE. & S. Brazil and NE. Argentina and Uruguay
    Distribution:
    Most of the United States, much of Central America, Europe, and parts of Africa, Asia, Australia, and New Zealand.
  • Whole Plant Traits:
    Plant Type:
    Water Plant
    Weed
    Habit/Form:
    Spreading
    Growth Rate:
    Rapid
    Maintenance:
    High
    Texture:
    Medium
  • Cultural Conditions:
    Light:
    Dappled Sunlight (Shade through upper canopy all day)
    Full sun (6 or more hours of direct sunlight a day)
    Partial Shade (Direct sunlight only part of the day, 2-6 hours)
    Soil Texture:
    High Organic Matter
    Loam (Silt)
    Sand
    Soil pH:
    Acid (<6.0)
    Alkaline (>8.0)
    Neutral (6.0-8.0)
    Soil Drainage:
    Frequent Standing Water
    NC Region:
    Coastal
    Mountains
    Piedmont
    USDA Plant Hardiness Zone:
    7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b
  • Fruit:
    Fruit Description:
    Plants do not set fruits in introduced areas.
  • Flowers:
    Flower Color:
    Cream/Tan
    White
    Flower Inflorescence:
    Solitary
    Flower Bloom Time:
    Spring
    Summer
    Flower Shape:
    Cup
    Flower Petals:
    2-3 rays/petals
    Flower Size:
    < 1 inch
    Flower Description:
    Sperate male and female flowers grow on terminal stems as they reach the surface. They have 3 creamy-white petals and are up to 1 inch across with female flowers being smaller. Blooms spring and summer
  • Leaves:
    Leaf Color:
    Green
    Leaf Type:
    Simple
    Leaf Arrangement:
    Whorled
    Leaf Shape:
    Oblong
    Leaf Margin:
    Serrate
    Hairs Present:
    No
    Leaf Length:
    < 1 inch
    Leaf Width:
    < 1 inch
    Leaf Description:
    Small, simple, oblong green leaves with finely serrated edges occur on plant shoots in whorls of 3-6 around the stem. They are 1 inch long and 1/4 inch wide
  • Stem:
    Stem Color:
    Green
    Stem Is Aromatic:
    No
    Stem Cross Section:
    Round
    Stem Description:
    circular stems have 6 to 12 double nodes
  • Landscape:
    Problems:
    Invasive Species
    Weedy