Myriophyllum aquaticum

parrotfeather flower.jpg

Parrotfeather - An escaped ornamental that is submerged until it grows long enough to reach the surface where it will then have emergent leaves. This plant has a unique highly hydrophobic property that allows its leaves to hold bubbles of air.

Leaves: Featherlike with whorled formation of 4 to 6 leaves. The subsurface leaves are darker than the emerged leaves which are bright green and resemble little fir tree seedlings.

Flowers: Inconspicuous whitish flowers found at the leaf axils of emerging stems during summer months.

Habitat: Found in freshwater ponds, streams, lakes and rivers. Tends to be rooted in shallow muddy areas but stems can grow up to 16 feet.

Weed Classification: B Select

This has been found at multiple points along the Chehalis river, in adjacent sloughs and in various waterbodies around the county.

Why is it a Noxious Weed?
Parrotfeather poses similar threats to aquatic ecosystems as most other aquatic invasives; it outcompetes natives, blocks sunlight, inhibits water flow and recreational activities. This noxious weed is especially prolific and can grow a new stem from every node of a dislodged or broken stem.

Control Recommendations:
WA State Noxious Weed Board
UC Davis Weed Report
King County Noxious Weed Board - Best Management Practices