Myriophyllum sibiricum

Northern Water-milfoil

COMMON WATER-MILFOIL, PARROT FEATHER*

NATIVE TO MAINE

NOTE: All leafy milfoils display a wide range of vegetative variability. All milfoils found in Maine waters should be considered “suspect” as potential invaders until a positive identification has been confirmed.

Habitat: Northern water-milfoil is found in the submersed plant community. It can grow in shallow water in coves of lakes or slow-moving streams.

Description: Northern water-milfoil is a submersed aquatic plant with feather-like finely divided leaves 1 to 5 cm long, with 5 to 12 pairs of thread-like leaflets on each leaf. The leaves are arranged in whorls (4 or 5 leaves per whorl) that are typically spaced as much as 1 cm apart along the stem. Flowers occur in the axils of bracts, arranged in whorls around a slender spike that emerges upright 4 to 10 cm above the surface of the water. The small reddish flowers of this plant are larger than the bracts. The bracts have smooth (entire), or slightly-indented, toothed margins (hand lens necessary). Toward the end of the growing season, egg-shaped winter buds (or turions) comprised of small stiff leaves are formed along the submersed stems.

Range: Northern water-milfoil is relatively rare in Maine, scattered in the remaining New England states, the northern United States, and Canada.

Annual Cycle: Turions provide the primary means of winter survival for northern water-milfoil. Produced toward the end of the growing season, the turions eventually separate from the parent plant, and remain dormant until the following spring when they unfurl and take root. The emergent flower spikes form early to mid summer, but reproduction by seeds is not common. Like most milfoils, northern watermilfoil readily propagates by fragmentation. Some water milfoils are known to hybridize with each other.

Value in the Aquatic Community: Northern water-milfoil is a food source for wildlife including water fowl. The plants provide shade and cover for fish and insect larva.

Look Alikes: May be confused with other water-milfoil species, water marigold, coontail, common bladderwort, white water crowfoot, yellow water crowfoot, fanwort, prickly hornwort or mermaid-weed.

*This is a good example of the confusion that may arise when using common names. Though northern water milfoil is sometimes referred to as “parrot feather,” this name is also used for one of the three invasive water-milfoils on Maine’s watch list, Myriophyllum aquaticum. The two “parrot feathers” are entirely different species, one a harmless Maine native, the other a non-native invader. Using the “northern water-milfoil” as the common name for M. sibericum will help to minimize confusion.