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Wetland Plants and Plant Communities of Minnesota and Wisconsin


(Myriophyllum verticillatum L.)

Water Milfoil
The leaf of a water milfoill
Figure 9 - Leaf



FIELD CHARACTERISTICS: An aquatic, perennial herb. The leaves are whorled in 4's and 5's, 2-4 cm. long, and highly dissected into thread-like divisions in a feather- like shape. The emerged leaves are stiffer and have wider segments than the submerged leaves on the same plant. Spikes are emerged to a height of 4-12 cm. Flowers are in the axils of modified leaves on the emerged spike. Flower parts are in 4's. In flower from July to September.

ECOLOGICAL NOTES: Water milfoil is found submerged in the quiet waters of lakes, rivers, and deep marshes, or rooting on muddy shores.

Two similar species of water milfoil (M. spicatum and M. sibiricum) are also very common and can become a nuisance by forming dense mats that interfere with swimming, fishing, and boating. In some parts of the nation there are large-scale aquatic weed control programs for controlling water milfoil.

SOURCE: Fernald (1970); Gleason and Cronquist (1991); and Voss (1985).

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