Parrotfeather (Myriophyllum aquaticum) is a submersed aquatic perennial that pushes its feathery floral spike above the water's surface. A member of the watermilfoil family (haloragaceae), it is considered to be native to South America, possibly Brazil. It was introduced into the U.S. in the late 1800s as an aquarium plant. Water garden enthusiasts who culture this plant need to take precautions to avoid potential escapement.
Growing in a variety of habitats ranging from lakes to wetlands, full sun to shade, parrotfeather can be spotted from a distance by its odd gray-green color. Stems are often a reddish hue when viewed up close. Although the plant is largely submerged, it is the stem tips portion (floral spike) that is readily seen and used to identify this species. The plant gets its name from the feathery appearance of the leaves tightly whorled along the floral spike.
Dense growths of parrotfeather provide breeding areas for mosquitoes and will degrade both water quality and habitat for fish and wildlife. It fouls intakes used to supply municipal drinking water and irrigation and becomes a navigation hazard. Parrotfeather should never be introduced to open waters.
Parrotfeather has spread through most of the subtropical regions of the South and along the West Coast. Recently, populations have been reported in more temperate zones. The plant reproduces by fragmentation. Although flowers can be found, only pistillate plants (no males) occur in the U.S., and no seeds are produced. The spread of this invasive plant parallels its sale and distribution by wetland nurseries and water garden hobbyist across the country. Most of the complaints about parrotfeather in North Carolina can be traced back to water garden escapement or intentional plantings through "pond beautification" efforts.
The best control method, as with all invasive species, is to avoid its introduction. Where infestations exist, herbicides are used to control or eradicate this nuisance plant