Eurasian Watermilfoil

(Myriophyllum spicatum)

Non-Native

Eurasian Watermilfoil has feather-like leaves with 14-20 pairs of leaflets whorled around the hollow stem along the entire length of the plant.

Description

Eurasian Watermilfoil has stems sometimes more than six feet long, and branching prolifically at the water’s surface. They are spaghetti-like and reddish-brown to whitish-pink. Leaves are typically less than half an inch long, divided all the way to midrib like a feather, and contain 14-20 pairs of thread-like leaflets. Eurasian Watermilfoil leaves are connected by a short stalk, four to five leaves are whorled around the stem, and they are spaced one-half to one and a half inches apart. The flower spike is on the same stem as the leaves, sticks out of water, and reddish flowers whorl around the stem.

There are eight species of watermilfoil in the Midwest, and the other seven are all native. Eurasian Watermilfoil and Northern Watermilfoil are often confused. Eurasian Watermilfoil contains 14 or more pairs of leaflets while Northern Watermilfoil contains five to 12 pairs. Eurasian Watermilfoil grows with less control than Northern Watermilfoil and will form large canopies at the surface of the water in short periods of time. It also fragments more, which adds to the unrestrained growth. Eurasian Watermilfoil relies on sprouts or fragments for reproduction and begins growing in cool spring waters (about 59˚ F). The early start, combined with quick growth to the surface forming canopies, gives this plant an advantage over native plants, crowding them out. Eurasian Watermilfoil is often confused for Coontail; Coontail feels rough when pulled through the hand and Eurasian Watermilfoil does not.

Location

Eurasian Watermilfoil can be found across the United States.

Propagation

Fragments, roots