Myriophyllum aquaticum, Parrotfeather Watermilfoil

Gardens & Landscapes, Invasive Species, Extension Master Gardener December 16, 2015 Print Friendly and PDF

Invasive Species: Myriophyllum aquaticum, Parrotfeather Watermilfoil

Parrotfeather watermilfoil is an herbaceous, rooted, submerged/emergent plant that invades aquatic habitats throughout much of the United States. Stems are stout and blue-green in color. Leaves are abundant, whorled, pinnately compound, and finely dissected. Submersed leaves are 0.6 to 1.4 in. (1.5 to 3.5 cm) long and have 20 to 30 divisions per leaf. Emergent leaves are 0.8 to 2 in. (2 to 5 cm) long, less divided, and greener than the submersed leaves. As only female plants occur in North America, reproduction occurs vegetatively. Inconspicuous flowers are formed in the axils of the emergent leaves in the spring (sometimes fall). Parrotfeather watermilfoil is found in lakes, ponds, and slow-moving streams where it can form dense mats of vegetation. These mats can clog waterways, impede boating traffic, disrupt the growth of native vegetation and provide a breeding ground for mosquitoes. Parrotfeather watermilfoil is native to South America and was first introduced into the United States in the Washington D.C. area around 1890 as an aquarium and aquatic garden plant.

What are invasive species and why should we be concerned about them? 


Taxonomy: Scientific and Common Names for This Species

Haloragales > Haloragaceae > Myriophyllum aquaticum (Vell.) Verdc.

Synonym(s): water-feather, Brazilian water-milfoil, parrotfeather

Myriophyllum aquaticum - USDA PLANTS Profile

Distribution Maps

Parrotfeather watermilfoil - The reported distribution of this invasive species across the United States (Source: Invasive Plant Atlas of the United States)

Up-to-the-minute distribution maps and why they are important 

Reporting This Invasive Species

What is the best way and place to report the occurrence of an invasive species? 

 How to report an invasive species sighting to EDDMapS - Early Detection & Distribution Mapping System

EDDMapS - Report an invasive species to EDDMapS.

Cooperative Extension Offices - Find your local Cooperative Extension office on this map provided by USDA.

How to Identify

This invasive species can be identified by looking for the characteristics described in the paragraphs that follow.

Plant

Herbaceous, rooted, submerged to emergent plant. Stems are stout and blue-green in color.

parrotfeather Parrot Feather
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Foliage

Leaves are abundant, whorled, pinnately compound, and finely dissected. Submersed leaves are 0.6 to 1.4 in. (1.5 to 3.5 cm) long and have 20 to 30 divisions per leaf. Emergent leaves are 0.8 to 2 in. (2 to 5 cm) long, less divided, and greener than the submersed leaves.

parrotfeather (Myriophyllum aquaticum)

parrotfeather Myriophyllum aquaticum (Vell.) Verdc.
Leslie J. Mehrhoff, University of Connecticut
Bugwood.org

Leslie J. Mehrhoff, University of Connecticut,
Bugwood.org

Flower

As only female plants occur in North America, reproduction occurs vegetatively. Inconspicuous flowers are formed in the axils of the emergent leaves in the spring (sometimes fall).

   
bugwood.org bugwood.org

Fruit

No fertile fruit is known to be produced in the United States.

   
bugwood.org bugwood.org

Native Species That Can Resemble Parrotfeather Watermilfoil

- Images at invasive.org

   
bugwood.org bugwood.org

- Images at invasive.org

   
bugwood.org bugwood.org

Additional Images for Parrotfeather Watermilfoil

Parrotfeather watermilfoil - Images at Invasive.org

Learning Resources for Parrotfeather Watermilfoil

Myriophyllum aquaticum Identification Card - US Fish & Wildlife Service

Myriophyllum aquaticum Fact Sheet - US Fish & Wildlife Service

Additional Information, Biology, Control and Management Resources

Control and management recommendations vary according to individual circumstances. Location, habitat, weather, and a variety of other conditions are factors that help determine the best treatment choice. To find the safest and most effective treatment for your situation, consult your state's land-grant institution. If you will use chemicals as part of the control process, always refer to the product label.

United States Land-Grant University System - Find your land-grant university's college of agriculture, Cooperative Extension office, or other related partner on this map provided by USDA.

Plant Invaders of Mid-Atlantic Natural Areas - National Park Service and US Fish and Wildlife Service

Invasive Plant Atlas of New England - University of Connecticut

Global Invasive Species Database - Invasive Species Specialist Group

Plant Profiles - Cal-IPC

Center for Aquatic and Invasive Plants - University of Florida IFAS

Invasive Plant Atlas of New England - University of Connecticut

Plant Invaders of Mid-Atlantic Natural Areas - USDA Forest Service & USDA APHIS PPQ


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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.