Elodea densa
Common Name(s):
Previously known as:
- Egeria densa
- Phonetic Spelling
- el-loh-DEE-ah DEN-sah
- Description
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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:
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- Tags:
- Cultivars / Varieties:
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- Tags:
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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.
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Whole Plant Traits:
- Plant Type:
- Water Plant
- Weed
- Habit/Form:
- Spreading
- Growth Rate:
- Rapid
- Maintenance:
- High
- Texture:
- Medium
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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
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Fruit:
- Fruit Description:
- Plants do not set fruits in introduced areas.
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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
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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
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Stem:
- Stem Color:
- Green
- Stem Is Aromatic:
- No
- Stem Cross Section:
- Round
- Stem Description:
- circular stems have 6 to 12 double nodes
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Landscape:
- Problems:
- Weedy