Eurasian Watermilfoil: The Aquatic Invader You Should Never Plant
If you’re considering aquatic plants for your water garden or pond, you might come across Eurasian watermilfoil (Myriophyllum spicatum). While this underwater plant might look appealing with its feathery, finely divided foliage, this is one species you’ll want to steer clear of entirely. Let me explain why this seemingly innocent aquatic plant has become one of North America’s most problematic aquatic invaders.
What is Eurasian Watermilfoil?
Eurasian watermilfoil, also known as spike watermilfoil, is a perennial aquatic forb that grows completely underwater except for its small flower spikes. This non-native species is classified as a forb, meaning it’s a vascular plant without significant woody tissue. While it might look delicate with its feathery underwater leaves, don’t let appearances fool you – this plant is a powerhouse of invasive growth.
Where Did It Come From and Where Is It Now?
Originally native to Europe and Asia, Eurasian watermilfoil has unfortunately made itself at home across North America. This invasive species has been introduced and now reproduces spontaneously throughout Alaska, Canada, and the lower 48 states. You can find established populations in nearly every state and province, from Alabama to Alaska, and from British Columbia to Florida.
Why You Should Never Plant Eurasian Watermilfoil
Here’s where things get serious. Eurasian watermilfoil isn’t just non-native – it’s aggressively invasive and regulated across multiple states:
- Alabama classifies it as both Category 1 invasive and a Class C noxious weed
- Connecticut lists it as Invasive and Prohibited
- Michigan considers it Invasive and Restricted
- Minnesota, New Hampshire, and other states have it listed as Prohibited
- Wisconsin restricts its use and transport
These classifications exist for good reason. Once established, Eurasian watermilfoil forms dense underwater mats that can completely take over water bodies, crowding out native aquatic plants and disrupting entire aquatic ecosystems.
The Problems It Causes
Eurasian watermilfoil might seem harmless floating in the water, but it creates significant problems:
- Forms dense mats that impede water recreation like swimming, boating, and fishing
- Crowds out native aquatic plants that provide better wildlife habitat
- Alters water chemistry and oxygen levels
- Can clog water intake systems
- Reduces property values along affected waterways
Wildlife Considerations
While Eurasian watermilfoil does provide some wildlife benefits – water birds and terrestrial birds occasionally use it for 5-10% of their diet – these minimal benefits are far outweighed by the ecological damage it causes to native plant communities that would provide much better wildlife habitat.
Growing Conditions (For Identification Purposes Only)
Understanding where and how Eurasian watermilfoil grows can help you identify and report it. This fully aquatic plant has an Obligate Wetland status across all regions, meaning it almost always occurs in wetlands. It thrives in:
- Still to slow-moving freshwater
- Lakes, ponds, and slow streams
- USDA hardiness zones 3-11
- Various water conditions from nutrient-poor to nutrient-rich
What to Plant Instead
Instead of risking the introduction of this invasive species, consider these native aquatic alternatives that provide excellent wildlife benefits without the ecological risks:
- Native pondweeds (Potamogeton species)
- Wild celery (Vallisneria americana)
- Coontail (Ceratophyllum demersum)
- Native water lilies
- Arrowhead (Sagittaria species)
If You Spot It, Report It
If you think you’ve identified Eurasian watermilfoil in a water body, contact your local environmental agency or extension office. Early detection and rapid response are crucial for preventing new infestations from establishing and spreading.
Remember, when it comes to Eurasian watermilfoil, the best approach is complete avoidance. Stick with native aquatic plants that will provide beautiful, sustainable habitat for wildlife while supporting healthy aquatic ecosystems. Your local waterways – and future generations – will thank you for it!
