Eurasian watermilfoil is a bay grass with whorls of feathery leaves along long, branching stems. It grows in quiet fresh and slightly brackish waters throughout the Chesapeake Bay watershed.
The Eurasian watermilfoil is made up of tough, branching stems that can grow to 8 feet long and delicate, feather-like leaves that grow in whorls of 4 to 5 along each stem. Leaves lose their shape when taken out of the water. Spikes of reddish flowers poke above the water’s surface in late summer. The plant has a rooted base.
This grass is common in slow-moving or protected fresh and slightly brackish waters; it cannot tolerate strong waves or currents. It often grows in sandy mud.
Native to Europe and Asia, Eurasian watermilfoil is found in the upper Chesapeake Bay from the Susquehanna Flats to just north of the Chesapeake Bay Bridge. It also grows in tributaries throughout the Bay watershed, from fresh non-tidal streams to slightly brackish tidal rivers.
This grass usually reproduces asexually when stem fragments form into new plants. It can also reproduce sexually in late summer, when female flowers are pollinated through the air and produce nut-like seeds that sink to the bottom. Seeds can remain viable for years.