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Parrot feather

(Myriophyllum aquaticum)

Photo of parrot feather
Photo credit: Leslie J. Mehrhoff, University of Connecticut,

Native to South America, but introduced nearly worldwide. Stems can be up to five feet long and trail along the ground or water surface, becoming erect and leafy at the ends.


Other names for this plant 
  • Common names: parrot feather watermilfoil, Brazilian water-milfoil, red-stemmed parrot feather
  • Scientific names: Myriophyllum brasiliense; M. brasiliensis.
Ecological threat
  • Invades shallow lakes, ponds, ditches and backwaters in rivers; will colonize all shallow waters, forming dense mats of vegetation that can entirely cover the surface of the water.
  • Tough stems make it difficult to boat, swim, fish or water ski; provides ideal habitat for mosquito larvae and the mass of the plant can cause flooding to occur.
 Overview map of prohibited classification in WI
Prohibited (red) counties

Classification in Wisconsin: Prohibited

Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. The recommendation for parrot feather was based upon this literature review [PDF] developed by the department.


Leaves: Emergent leaves are bright blue-green, stiff and two to five centimeters long, arranged in whorls of three to six leaves around the stem and divided into 12-36 leaflet pairs; underwater leaves are often decayed, but if present, they are limp, 1.5-3.5 cm long and are divided into 10-15 leaflet pairs per leaf.

Flowers: Tiny (0.5 mm) flowers with four white sepals occur individually on short stalks at the base of the emergent leaves; male and female flowers are on separate plants, but only female plants are found in North America.

Fruits & seeds: Because there are only female plants in North America, no fruits are produced here. Spreads through fragmentation of the stems and rhizomes.

Roots: Many, thin, from rhizomes.


Currently, there have been no reports of parrot feather in Wisconsin. Have you seen it? Send us a report.


Mechanical: Attempting control by manual or mechanical means tends to spread the plants and should only be conducted in small, contained water bodies. Draining a pond in the summer achieved control in one instance, but draining may not achieve control in winter.

Chemical: Control with herbicides is difficult because the emergent stems and leaves have a waxy cuticle that repels herbicides. Chemicals that have been used successfully against parrot feather water-milfoil include diquat, diquat and complexed copper, endothall dipotassium salt, endothall and complexed copper, and 2,4-D. If using glyphosate formulated for aquatic use plus a surfactant, apply during the low water levels of summer and fall for more complete coverage. Consult with your natural resources department before beginning herbicide control.

Biological: Plant-eating sterile grass carp find parrot feather unpalatable due to the tough, woody stems and high tannin content of the plants.


View parrot feather pictures in our photo gallery.


Sources for content
  • Czarapata, Elizabeth; Invasive Plants of the Upper Midwest: an illustrated guide to their identification and control. University of Wisconsin Press. 2005. Pg. 147
  • Swearingen, J., K. Reshetiloff, B. Slattery, and S. Zwicker. 2002. Plant Invaders of Mid-Atlantic Natural Areas. National Park Service and U.S. Fish & Wildlife Service, 82 pp. Invasive Plants of the Eastern U.S. Parrot Feather Watermilfoil [exit DNR].
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