The Frog Blog – Aquatic Weed Wednesday

Eurasian Watermilfoil

Eurasian watermilfoil (Myriophyllum spicatum)

Happy Wednesday! Today we will talk a little bit about a very common invasive aquatic species (AIS) found in Ohio waters and across the US called Eurasian watermilfoil (Myriophyllum spicatum).

Eurasian watermilfoil is a pesky aquatic plant that can be quite the headache to manage! Introduced into the US from Eurasia, the plant has few predators in our ponds and lakes. As a result, Eurasian watermilfoil can potentially outcompete native species and easily “choke-out” smaller waterbodies. It has finely divided leaves that whorl around the plant’s stem (usually 4 – 5 leaves per whorl) and resemble a feather of sorts. Each feathery leaf will have 14 – 20 opposite pairs of smaller leaflets.  The number of leaflets is important to consider since a rarer native species called Northern watermilfoil has 5 – 12 pairs and looks extremely similar to its Eurasian cousin.

Many different management techniques have been utilized to try and limit or eradicate Eurasian watermilfoil from ponds and lakes. Herbicides may be the most commonly used because of cost and effectiveness but, others have tried non-herbicide techniques as well. These include hand-pulling, mechanical harvesting, the use of benthic mats, and even some interesting biocontrol organisms. All of these techniques have pros and cons as well as techniques that can increase their effectiveness so checking with a specialist is always suggested.

By: Edward Kwietniewski

Aquatic Biologist

AQUA DOC Lake and Pond Management

Edward Kwietniewski graduated from The State University of New York College of Environmental Science and Forestry (SUNY ESF) with a Bachelor’s degree in Aquatics and Fisheries Science. He also has a Master’s degree in Lake Management from the State University of New York College at Oneonta (SUNY Oneonta). He has a love for all things aquatic and is an avid fisherman.

Resources and External Links

Borman, S., Korth, R, and Jo Temte. Through the Looking Glass: A Field Guide to Aquatic Plants. Stevens Point, Wis. :Wisconsin Lakes Partnership, 1997. Print.



Edited by: Sharon Daneshmand