Parrotfeather
Myriophyllum aquaticum
Washington State Classification
Class B — Control Required (Designated)
Parrotfeather is an ornamental aquatic plant that has escaped cultivation.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
It is a submerged aquatic plant and has emergent and submersed leaves. It is occasionally found on mud banks. Long rhizomes and stems intertwine to form dense mats. Stems grow to 16 feet long.
Leaves
Leaves are feather-like and arranged in whorls of 4 to 6 leaves. Emergent leaves are bright green and look similar to little fir trees. Submersed leaves are darker.
Flowers
Flowers are inconspicuous and white in leaf axils of emergent stems.
Impact
Parrotfeather is an ornamental aquatic plant that has escaped cultivation. Infestations can alter aquatic ecosystems. It forms dense mats that shade out other native aquatic plants as well as inhibit water flow and recreational activities.
Ecology & Spread
Habitat
Parrotfeather is found in freshwater ponds, streams, lakes and canals. Please click here to see a county level distribution map of parrotfeather in Washington.
Spread Mechanisms
Reproduction
Since only female plants are present in North America, parrotfeather reproduces by stem and rhizome fragments.
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Control Methods
Mechanical
- Mechanical methods are not advised unless an area is entirely invaded by plants; otherwise, mechanical methods may increase infestation.
Cultural / Prevention
- Reduce weed infestation by handpulling weeds. Digging and carefully removing all rhizomes will effectively eliminate single plants and small infestations.
Biological Control
- Parrotfeather is unpalatable to grass carp.