Parrot Feather (Myriophyllum aquaticum)




Photo: Andre Karwath (

By David Newell, North-Eastern Lake Ontario Steward


Parrot feather (Myriophyllum aquaticum), also called Brazilian watermilfoil is an invasive aquatic plant in lakes, ponds, and streams throughout New York State. Parrot feather is a close relative to the more aggressive invasive species Eurasian watermilfoil and sometimes gets mistaken for Eurasian watermilfoil. Parrot feather is native to most of South America. Parrot feather was brought into the United States in the 1800s by the aquarium industry, it’s a very popular indoor and outdoor aquatic garden plant. Parrot feather got into the local waterways by escaping from its outdoor ponds or being spread by aquarium owners when they dump their aquarium and all of its contents into a waterway. Once in the waterway it can spread rapidly and take over.

Species Description:

Parrot feather gets its name for the very bright green leaves that look like a feathers, the leaves are arranged around the stem in whorls of four to six leaves per whorl. Parrot feather can have both submersed and emergent leaves. The submersed leaves are commonly mistaken for Eurasian watermilfoil. The submersed leaves are a less dark green and less stiff than the emergent leaves. The emergent stem and leaves resemble a parrot feather tail hence the name parrot feather. The emergent stems can grow up to a foot out of the water and extend out several yards over the water’s surface. The submersed leaves on the other hand are usually limp and appear as if they are decayed. The flowers are inconspicuous and are found on the emergent section of the plant. The flowers are white and only 1/16th of an inch long.

How Parrot feather spreads and its preferred habitat:

Only female Parrot feather plants are known to occur in the United States, therefore typical plant reproduction does not occur with the parrot feather. Thus the only way for new plants to grow is by plant fragmentation. The fragmented bits of plant material can create new plants. This means that boat propellers going through patches of Parrot feather can increase the patch size and their spread. The plant can also spread by flooding, fragments stuck on birds, watercraft, and plant fragment floating downstream. Parrot feather prefer shallow slow-moving nutrient rich water. It is common in shallow water as a rooted plant.

Ecological and economic impact:

Parrot feather offers some cover for aquatic organisms, but offers little food value for wildlife, and alerts the aquatic environment. The dense patches of Parrot feather shade out native plants and algae which serves as aquatic food. After the dense patches of Parrot feather dies off, there decompose and can create a low oxygen conditions which can harm aquatic organisms. The large vegetation mats that Parrot feather forms can cause economic impact as well. The mats make it difficult to navigate and are restricting to recreational activates such like boating, fishing, and swimming. Parrot feather can also decrease aesthetic value, thus decreasing property values.

Control Methods:

With chemical control of Parrot feather there has been some success but it is difficult to achieve complete control. Repeated chemical treatments are needed to produce some type of success. Many herbicides have been tried on Parrot feather, but one go to herbicide hasn’t been found yet. A wetting agent is required to penetrate the waxy emergent leaves. It is more effective when applied to young plants. There has been no biological control found yet for Parrot feather but there are some that are being looked into such as the use of beetles or other insect species. Mechanical control is to not be used unless it is needed to break up the dense mates to let sunlight enter waterway. This is because mechanical harvesting create plant fragmentation, and thus makes the infestation worse than it already was.

What can you do:

Always make sure to clean off your boat, trailer, equipment from hanging plant material, this will help stop with the spreading of Parrot feather. Make sure to always drain the bilge or live wells, along with any compartment on that has water in it. Lastly make sure dry the watercraft, and any equipment that was used before entering a new waterway.

Remember to always Clean, Drain, Dry



“Non-native Invasive Freshwater Plants.” Washington State Department of Ecology, Official Homepage. N.p., n.d. Web. 11 June 2016. <;.


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