What is Eurasian Water-Milfoil?
IMPORTANT: Eurasian water-milfoil (Myriophyllum spicatum) is an INVASIVE species, NOT native to Quebec.
Eurasian water-milfoil is an invasive submerged aquatic plant native to Europe, Asia, and North Africa. This highly invasive species was accidentally introduced to North America in the 1940s, likely through ship ballast water or the aquarium trade. It was first established in Quebec in 1958 in the St. Lawrence River and now colonizes over 200 water bodies in the province.
Eurasian watermilfoil has slender stems up to 2.5 meters long, with submerged leaves arranged in whorls of four around the stem. The plant forms dense grass beds with spikes of small flowers that emerge from the water (late July-early August).
How to Identify Eurasian Water-Milfoil
Key characteristics:
- Leaves: Feather-like leaves arranged in whorls of 3-6 (often 4) around the stem, composed of 12-24 pairs of thread-like leaflets
- Leaf length: Usually between 15-35 mm long
- Out-of-water behavior: Leaves become limp and collapse against the stem when the plant is removed from water
- Stems: Typically light brown, sometimes pink, with tips often red or pink in color
- Flowers: Inconspicuous, orange-red flowers, 4-6 mm long, produced on a 5-15 cm spike held vertically above the water surface
Differentiating from Beneficial Native Species
It is absolutely essential to distinguish INVASIVE Eurasian water-milfoil from native species that play vital roles in the lake ecosystem:
Northern Water-Milfoil (Myriophyllum sibiricum) - ESSENTIAL NATIVE SPECIES TO PROTECT:
- NATIVE to Canada for millennia - this species MUST be preserved
- Has only 5-9 pairs of leaflets (versus 12-21 for the invasive species)
- Leaves remain rigid when out of water
- Produces turions (winter buds) which Eurasian water-milfoil does not
- Branches sparsely unlike Eurasian water-milfoil which branches profusely
- Provides quality habitat for native invertebrates and fish
Other native species not to confuse:
- Coontail (Ceratophyllum demersum): Its rigid leaves retain their shape out of water
- Bladderworts (Utricularia spp.): Carnivorous plants with modified leaves (small black vesicles) that act as floats and insect traps
- Myriophylle verticillé (Myriophyllum verticillatum) : Autre espèce de myriophylle indigène
⚠️ DANGEROUS CONFUSION: There are 6 native milfoil species in Quebec. Only experts can differentiate them with certainty, highlighting the absolute importance of professional intervention.
Devastating Ecological Impacts
Densely populated areas of Eurasian milfoil create an ecosystem with fewer food sources for surrounding fish due to the plant's inability to provide the same microhabitat for invertebrates created by native aquatic plant species. Impacts include:
- Aggressive competition: Crowds out native plants and creates dense mats that interfere with recreational activity
- Hypoxic zones: Dense growth blocks sun penetration to native aquatic vegetation, preventing them from photosynthesizing
- Fisheries impact: Creates microhabitats for juvenile fish and obstructs space for larger fish, ultimately disrupting normal feeding patterns
- Biodiversity reduction: Forms thick mats of vegetation on the surface that block light, reducing biodiversity and deoxygenating water when decomposing
⚠️ WARNING: Why You Should NEVER Attempt Removal Yourself
Risk to native species: Any unprofessional removal attempt can accidentally destroy precious native species that resemble Eurasian water-milfoil. The 6 native milfoil species in Quebec are essential for the ecosystem and their accidental elimination could cause irreversible ecological damage.
Explosive proliferation through fragmentation:
Eurasian watermilfoil grows primarily from broken off stems, known as shoot fragments, which increases the rate at which the plant can spread and grow. Each unprofessional manipulation can:
- Multiply the problem: A single fragment can establish a new colony
- Spread the invasion: Trailering boats has proven to be a significant vector by which Eurasian milfoil is able to spread and proliferate across otherwise disconnected bodies of water
- Worsen the situation: Manual pulling attempts can fragment the plant and create hundreds of new infection points
Our Professional Approach
Hand-harvesting by trained divers with proper techniques has been able to effectively control and maintain many lakes. Our team uses scientifically validated methods including:
- Preliminary assessment by specialized biologists
- Complete removal techniques including root systems
- Containment protocols to prevent dispersal
- Post-intervention monitoring to ensure effectiveness
Contact Us
If you suspect the presence of Eurasian water-milfoil in Lake Pope waters, do not attempt to remove it yourself. Contact our professional team immediately.
Références scientifiques / Scientific References
- Aiken, S.G., P.R. Newroth, and I. Wile. 1979. The biology of Canadian weeds. 34. Myriophyllum spicatum L. Canadian Journal of Plant Science 59(1):201-215.
- Madsen, J.D. 1998. Predicting invasion success of Eurasian watermilfoil. Journal of Aquatic Plant Management 36:28-32.
- Smith, C.S. and J.W. Barko. 1990. Ecology of Eurasian watermilfoil. Journal of Aquatic Plant Management 28:7-14.
- Borrowman, K.R., E.P.S. Sager, and R.A. Thum. 2014. Distribution of biotypes and hybrids of Myriophyllum spicatum and associated Euhrychiopsis lecontei in lakes of central Ontario. Lake and Reservoir Management 30:94-104.
- Ministère de l'Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs du Québec. 2024. Guide d'identification des plantes aquatiques envahissantes en eau douce au Québec.
Images:
Plants de myriophylle à épis submergés. Crédit photo : Ministère de l'Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs du Québec
Submerged Eurasian Watermilfoil plants. Photo credit: Ministère de l'Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs du Québec
Eurasian Water-Milfoil: A Silent Threat to Lake Pope