Scientific name: Myriophyllum aquaticum

What Is It?

Parrotfeather is a bright green aquatic plant with leaves that grow above the water and resemble tiny fir trees. It grows in slow moving rivers, ditches, and shallow freshwater lakes and ponds, as well as on wet soil along shorelines. Parrotfeather rapidly forms dense mats of vegetation that can take over shallow lakes, ponds, and ditches. It is native to South America.

Is It Here Yet?

Yes. Parrotfeather has been documented across western Washington, and, to a limited extent, in eastern Washington.

Why Should I Care?

Parrotfeather rapidly takes over shallow lakes, ponds, and ditches by forming dense mats of vegetation that can cover the water surface entirely, accelerate flooding, block passage for salmon, shade out algae that form the base of the aquatic food web, cause water quality issues, and provide habitat for mosquito larvae. Its tough stems present challenges to boaters, swimmers, and other water recreationists.

How Can We Stop It?

Do not purchase, plant, or trade this species. Parrotfeather is on Washington’s Wetlands and Aquatics Quarantine list, meaning it is prohibited to transport, buy, sell, offer for sale, or distribute parrotfeather plants or plant parts. Parrotfeather is listed as a Class B noxious weed in Washington, meaning it is designated for control in certain state regions. Parrotfeather plant fragments may get stuck on boats and resprout in other water bodies the boat enters. Clean, drain, and dry boats before transporting them elsewhere.

What Are Its Characteristics?

  • Parrotfeather has bright green, stiff, fir-tree-like foliage that can extend up to 1 foot above the water, and resemble very small fir trees.
  • It has leaflets in whorls of 4-6 around the stem, with feather-like leaf arrangements.
  • The plant forms a dense mat of intertwined brownish stems in the water, and may have reddish, feathery-leaved, limp underwater leaves.
  • Parrotfeather differs from the invasive Eurasian watermilfoil in that it has above-water leaves.

Additional Photographs