Myriophyllum aquaticum (Vell.) Verdc.: Parrotfeather. Haloragaceae (watermilfoil family).
Exotic perennial. Grows from rhizomes in shoreline mud or in water depths to 3.3 ft (1 m), often with all or most of the plume-like plant emergent. Can form large dense colonies and compete with other emergent aquatic plants. Stems can be reddish and up 6.5 ft (2 m) long. Emergent foliage is soft and feathery, a striking light- to gray-green, with a waxy-looking bloom. The rather stiff emergent leaves are in whorls, 3 to 6 leaves around the stem, and up to 2 in (5 cm) long. The individual leaf resembles a tiny narrow feather; it is made up of 20 or more paired leaf divisions that are shorter than in most other milfoils. Underwater leaves are similar, but more flexible and a little longer. Inconspicuous flowers can occur around stems at base of leaves, but are not often produced. This species spreads by underground stems or from rooted stem pieces, and is able to produce dense stands that hinder water use and degrade habitat.
