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| NAS - Nonindigenous Aquatic Species |
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Common Name: parrot feather, Brazilian watermilfoil
Synonyms and Other Names: Enydria aquatica, M. brasiliense, M.proserpinacoides
Taxonomy: available through 
Identification:
Myriophyllum aquaticum is rooted in the substrate with part of the stem
beneath the surface of the water and a conspicuous emergent portion. Creeping rhizomes may give rise to multiple stems, which are red to green, 2-5 mm in diameter and may grow 2 meters in length.
Emergent portions are composed of pinnately dissected leaves arranged in whorls of 4-6 around the central stem and may rise up to 30 cm above the water surface. The waxy, bright green or bluish-green emergent leaves are 2-5 cm long with 12-36 leaflets (6-18 leaflet pairs). Submersed leaves are often missing or decayed, but if present are limp, 1.5-3.5 cm long with 20-30 leaflets (10-15 leaflet pairs). If emergent portions have not yet formed, submersed leaves are often mistaken for other Myriophyllum species.
Stems branch and root at the nodes allowing for the formation of fragments. Because only pistillate (female) plants occur in North America, all reproduction is asexual through vegetative fragments, but flowers do form in the axils of slightly modified leaves on emergent portions. Aiken (1981) provides a detailed key for flowering specimens.
Native Range:
South America (Brazil, Bolivia, Ecuador; Peru, Argentina, Chile, Paraguay)
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 Alaska |
Hawaii |
Caribbean |
Interactive maps: Continental US, Alaska, Hawaii, Caribbean
Nonindigenous Occurrences: Naturalized in Asia, Australia, New Zealand, southern Africa and regions of the United States. First introduced to the U.S. as an ornamental pond plant, perhaps as early as the late 1800's.
Ecology: Slow-moving water in rivers, lakes, ditches and ponds; prefers nutrient rich waters. Stems may grow along shorelines in wet soils, surviving periods of drawdown.
Means of Introduction: Escaped ornamental pond plant
Status:
Impact of Introduction: Dense infestations can completely colonize small ponds and sloughs; impede water flow in drainage ditches and irrigation canals and may out-compete native macrophytes.
Remarks:
References
Author: V. Howard Morgan
Revision Date: 3/11/2009 Citation for this information:
V. Howard Morgan. 2009. Myriophyllum aquaticum. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=235> Revision Date: 3/11/2009
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