Invasive Aquatic Plants

Invasive plants can have just as much of an impact as invasive animals! Invasive aquatic plants can reduce the habitat for our native plants, which threatens species of insects, fish, animals and other plants that depend on native plants. As invasive plants begin rapidly reproducing, they reduce the overall biological diversity of ecosystems, can effect on water quality and interfere with recreational opportunities.

Invasive Aquatic Plant Profiles

Eurasian Watermilfoil (Myriophyllum spicatum)

Eurasian watermilfoil (Myriophyllum spicatum)

Place of Origin/When Introduced

  • Originally from Eurasia, it was introduced to North America in 1961 in Lake Erie. To our knowledge, Eurasian watermilfoil is currently not present in Alberta.

Habitat

  • Prefers shallow water, but can root up to 10 metres in depth.

Identification

  • Perennial, submersed; flowers are very small, reddish, and held above water on an emersed flower spike.
  • Usually 12 to 21 closely leaflet pairs per leaf.

Reproduction

  • A single segment of stem and leaves can form a new colony; plant does produce seeds but germination rates are usually poor. Stem fragmentation and underground runners allow this plant to reproduce rapidly.

Issues

  • Forms large, floating mats that prevent light penetration into waterbodies, out-shading native plants and reducing oxygen levels when decomposing.
  • Outcompetes native milfoils.

Related Information

For more information on comparing native and invasive milfoil see:

Flowering Rush (Butomus umbellatus)

Flowering Rush (Butomus umbellatus)

Place of Origin/When Introduced

  • Originally from Eurasia, was introduced as an ornamental garden plant in the 1890s. Flowering rush is now found across Canada and the United States

Habitat

  • Can grow as an emergent plant along shorelines, or as a submersed plant in lakes and rivers up to 4 metre depth.

Identification

  • A perennial, surviving winters and droughts.
  • Cross section of stem is triangular.
  • Easiest to identify when flowering in summer months; each umbrella-shaped cluster has whitish pink pedals up to 1.5 metres in height. Flowers are only produced in very shallow water or on dry sites.
  • Looks similar to cattails (Typha latifolia), rushes (Juncus spp.) and bur-reeds (Sparganium spp.)

Reproduction

  • Can reproduce by breaking the root system or by seed.

Issues

  • Dense stands in irrigation ditches can reduce water availability, and in lakes can interfere with boat propellers and swimming.

Current Management in Alberta

Alberta Environment and Parks has partnered with several organizations to study eradication methods on Lake Isle.

Hand digging, mechanical harvesting, bottom barriers and herbicide treatments were completed in two-by-two metre plots. The effectiveness of each method will be evaluated in 2017.

The application of an herbicide to decrease the population and density of flowering rush was also used in Buffalo Creek near Innisfail.

Related Information

Phragmites (Phragmites australis australis)

Phragmites (Phragmites australis australis)

Phragmites Treatment

Place of Origin/When Introduced

  • Originally from Eurasia, it is unclear how this subspecies of phragmites was introduced to Canada. Phragmites australis australis was found in two locations in Alberta near Brooks in March of 2016.

Habitat

  • Grows in shallow water, up to 1 metre near the water’s edge of stationary or slow moving water such as that found in wetlands.

Identification

  • Perennial, aquatic or subaquatic, with large stems up to 4 metres tall.
  • Alternating leaves, 25 to 50 centimetres long and 1 to 5 centimetres wide.
  • Feathery seedhead with several flowered spikelets that are 10 to 18 millimetres long.

Issues

  • Highly competitive and form dense stands, outcompeting native plants for water and nutrients.

Current Management in Alberta

  • Both stands of phragmites found in Alberta were treated in 2016. The terrestrial stand was treated with herbicides, while the stand in water was cut and burned.

What can you do to help stop the spread of invasive plants?

Report it!

If you spot an invasive species, call 1-855-336-2628 (BOAT).

Learn more about identifying and preventing some of the most damaging plant species for lakes and rivers:

Spread the word, not the plant!

Print off a Don’t Let it Loose poster and tell you friends about the threats invasive plants pose!

Related Information

Alberta Agriculture and Forestry

 

Page Information

Updated: Oct 5, 2017