Parrotfeather (Myriophyllum aquaticum)

This aquatic invader has been spotted just downstream from our lake.  What a pest this will be.  

http://www.ecy.wa.gov/programs/wq/plants/weeds/aqua003.html

Technical Information

Description 

Parrotfeather (Myriophyllum aquaticum) gets its name from its feather-like leaves which are arranged around the stem in whorls of four to six. Parrotfeather has both submersed and emergent leaves, with the submersed form being easily mistaken for Eurasian watermilfoil (Myriophyllum spicatum), a close relative. The submersed leaves are 1.5 to 3.5 centimeters long and have 20 to 30 divisions per leaf. The emergent leaves are 2 to 5 centimeters long and have 6 to 18 divisions per leaf. The bright green emergent leaves are stiffer and a darker green than the submersed leaves. The emergent stems and leaves are the most distinctive trait of parrotfeather, as they can grow up to a foot above the water surface and look almost like small fir trees. Submersed leaves are limp and often appear to be decaying but the stems are very robust. Adventitious roots form at the nodes. When attached to a bank, parrotfeather stems can extend out several yards over the water surface. Flowers are inconspicuous and are borne in the axils of the emergent leaves. The white flowers are approximately 1/16 inch long.