Eurasian Water-milfoil is an invasive aquatic plant native to Eurasia and North Africa. Introduced to North America in the 19th century, it is now one of the most widely distributed invasive aquatic plants on the continent. Its method of introduction is contested, but it is suspected to have been introduced to the Great Lakes from ballast water and transported around the province from recreational boats. Since tiny plant pieces of Eurasian Water-milfoil can develop into new plants, it is easily spread when water currents, boat propellers, trailers, or fishing gear carry plant fragments to new areas.
First discovered in Lake Erie in 1961, Eurasian Water-milfoil has spread to all of the Great Lakes, the St. Lawrence River, many inland lakes throughout southern and central Ontario, and much of the United States. It can now be found across every continent, except Antarctica. It has also become the dominant vegetation in the northern part of the OAC.
- Fast growing aquatic plant that can quickly overtake native vegetation once introduced and left unchecked
– Some native aquatic species (example??) are picky about where they live and nest, so this can not only further harm existing SAR, but other species as well
- Can contribute to low oxygen conditions leading to fish kills due to thick mats of decaying plant material
- Can hybridise with native Northern Water-milfoil (Myriophyllum sibericum) to create a more aggressive form of the invasive species
- Dense stands can create stagnant water, which is an ideal habitat for mosquitoes.
- Grows in such thick mats that it can hinder recreational activities such as swimming, boating, and fishing
How to Identify:
- Feather-like green leaves circle the stem in groups of four or five
- Each leaf typically has 24 or more thread-like segments
- Tiny, reddish flowers grow on spikes 5 to 20 cm long that rise above the water towards late summer (August-September)
- Eurasian water-milfoil looks similar to the native northern water-milfoil (Myriophyllum sibiricum), but the native species typically only has leaves with 24 or fewer leaf segments
– Hybridisation can make identification very difficult as it can cause overlap between the 2 species, requiring genetic analysis to be certain
– Early season leaf growth and leaves on floating fragments of Eurasian watermilfoil can also resemble native Northern Water-milfoil. However, In the late summer and fall, native Northern Water-milfoil will form turions (overwintering buds) at the stem tips that look like short segments of dark, densely crowded leaves – Eurasian watermilfoil will not form these buds.
– Eurasian watermilfoil typically will branch near the surface of the water, whereas the native Northern Water-milfoil will stem branches lower in the water column and less abundantly
How you can help:
- Learn how to identify Eurasian water-milfoil
- Prevent accidentally spreading this plant – Clean, Drain, Dry your boat, trailer, waders, and other equipment after each use. Remove all plants, animals, and mud before moving to a new waterbody.
- Avoid infested areas or reduce your speed when travelling near Eurasian water-milfoil infestations. Your propeller can dislodge fragments and spread the pieces to new areas as new plants can grow from small pieces of the plant.
- Do not plant Eurasian water milfoil in your aquarium or water garden. Aquarium hobbyists and gardeners should only use native or non-invasive plants and are encouraged to ask retailers for plants that are not invasive.
- Never release unwanted aquarium plants or pets. Return or donate unwanted plants to a garden centre, pet store, or put them in the garbage. Aquatic plants can be composted so long as the compost is at least 30m from the water’s edge.
- Organize or engage in community aquatic invasive plant pulls
If you find Eurasian water-milfoil or another suspected invasive species in the wild, please contact the toll-free Invading Species Hotline at 1-800-563-7711, visit EDDMapS Ontario, or search for the ‘Invasive Species in Ontario’ project on iNaturalist.org to report a sighting. For further information on invasive species and how to identify them, go to www.invadingspecies.com
Phragmites australis subsp. australis
While not detected yet within the Old Ausable Channel, this invasive reed has the potential to stir up trouble. Sometimes known as European Common Reed, Invasive Phragmites was declared as our nation’s worst invasive plant species in 2005 by Agriculture and Agrifood Canada. Once introduced to an area, Invasive Phragmites spreads quickly. It outcompetes native plants by releasing toxins into the surrounding soil from its roots. Aquatic habitat suffers greatly in dense thickets of this species, which has also been documented lowering water levels in some wetlands. While primarily aquatic in nature, Invasive Phragmites can still survive in relatively dry areas due to its extensive root system.