Myriophyllum aquaticum is a flowering plant, a vascular dicot, commonly called parrot's-feather[2] and parrot feather watermilfoil.

The emergent stems and leaves are the most distinctive trait of parrot feather, as they can grow up to a foot above the water surface and look almost like small fir trees.

The plant has whorls of feathery blue-green to waxy gray-green leaves deeply cut into many narrow lobes.

It was first discovered in the United States in the 1890s in Washington, D.C.[4] Parrot's feather typically grows in freshwater streams, ponds, lakes, rivers, and canals that have a high nutrient content.

[8] In Florida in the United States, flea beetles have been found to use parrot feather as a host for their larvae.

[citation needed] Because of its attractiveness and ease of cultivation, parrot feather has been introduced worldwide for use in indoor and outdoor aquaria.

While parrot feather may provide cover for some aquatic organisms, it can seriously change the physical and chemical characteristics of lakes and streams.

[4] The parrot feather grows abundantly, shades out naturally occurring algae, and clogs irrigation ducts and canals.

[8] In the U.S. states of Alabama, Connecticut, Massachusetts, Maine, Vermont, and Washington, parrot feather is a declared noxious weed and is therefore banned from sale.

[citation needed] The physical aspects of removal are such acts of cutting, harvesting, and rotovation (underwater rototilling).

[13] This implies that this species cannot be imported, cultivated, transported, commercialized, planted, or intentionally released into the environment in the whole of the European Union.