Parrot Feather (Myriophyllum aquaticum)

Also known as Brazilian water milfoil.

Description

Parrot feather is an herbaceous aquatic plant that grows to a length of 6.5 to 16 feet. Its stems are greenish blue with numerous small leaves that resemble feathers. The leaves are either submersed or emergent and grow in whorls of 4 to 6 around the stem. Emergent stems are bright green in color and can reach up to a foot above the water surface. The emergent leaves are also vibrantly green, grow to 2 inches long, and have 6-18 divisions per leaf. The submersed leaves are only 1.25 inches long with 20-30 divisions per leaf and are dark green and limp. Barely visible flowers grow from between the stem and the emergent leaves.

Look-alikes

This species is easily confused with the native water milfoils and the invasive Eurasian water milfoil.

Impacts & Habitat

Parrot feather is native to the Amazon in South America, but has spread to the east and west coasts of the United States as well as some Midwestern states. It prefers warm mild climates although it can survive temperate winters. Parrot feather grows best in still waters such as lakes, ponds, quiet streams and drainage ditches, but is able to survive in rivers. Vegetative reproduction is the only dispersal agent because female plants are not found in the United States. Parrot feather infestations can cause drainage problems in shallow rivers and streams as well as impeding recreational and commercial boating and fishing. It alters river and lake ecosystems by shading out the water column, disrupting native plant growth and providing breeding ground for mosquitoes.

Control

As fragmentation may cause more dispersal, mechanical control is not recommended unless all habitats are infested. The emergent steams and leaves of parrot feather have a waxy coating so a surfactant is necessary for herbicide penetration. Use only herbicides approved for open waters. Successful control has been achieved by using Glyphosate and 2,4-D, diquat, diquat and complexed copper in summer or fall when water levels are low.

Additional Information (Links exit DNR)

A Noxious Aquatic Weed in Washington
USDA
USGS