Myriophyllum spicatum

Eurasian watermilfoil

Family: Haloragaceae

Origin: Eurasia and Africa

Close up of Eurasian watermilfoil floating in the water.
Forms thick mats in the water excluding natives.
Photo credit: Barry Rice, The Nature Conservancy Wildland Invasive Species Team

Regional Pest Management Plan (RPMP) status

  • Unwanted organism

View more about the RPMP statuses

General description

Perennial submerged rhizomatous aquatic herb. Stems are long, branching and smooth. Leaves are soft, pinnate, feather-like and borne in whorls of four. Flowers are small, yellow and borne on emergent spike. Fruits contain four seeds.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell Eurasian watermilfoil. As Eurasian watermilfoil is an Unwanted Organism, these restrictions apply within the Auckland region and across the whole of New Zealand.

Habitats

Rivers, lakes, streams, reservoirs, ponds, drains, tidal creeks, bays.

Dispersal

Sets seed. Vegetative spread from runners and stem fragments. Seed and stem fragments dispersed by water. Human-mediated dispersal through movement of contaminated boats, equipment and machinery.

Impact on environment

Forms dense mats, outcompeting native plants and altering habitat structure. Impedes drainage and recreational activities.

Control

Recommended approaches

Do not attempt to undertake control of this species. Please report to Auckland Council.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Close up of a hand holding a stalk of Eurasian watermilfoil.
Leaves are feather-like and form in whorls of four.
Photo credit: Barry Rice, The Nature Conservancy Wildland Invasive Species Team