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.

Related Information

Himalayan Balsam

Himalayan Balsam

Place of Origin/When Introduced

  • Native to the western Himalayans, however it is widely known as an invasive alien in temperate areas of Europe, Asia, North Amercia and New Zealand. It was likely introduced to North America as an ornamental plant. Himalayan Balsam has been found in Alberta along watercourses.

Habitat

  • Grows in moist, nutrient rich soil and thrives in disturbed riparian habitats and wet woodlands.

Identification

  • Himalayan balsam leaves are simple, oblong-shaped with serrated edges, arranged oppositely on a square, hollow stem.
  • Leaf veins and stems have red to purple tinges. Flowers are irregular with five purple to pink to white petals and resemble an English policeman’s helmet.
  • Round brown seeds are released explosively when a ripened capsule is disturbed or dried.

Reproduction

  • It is only able to reproduce by seed; however, a single plant can produce up to 4,000 seeds that launch up to ten metres in all directions.

Issues

  • Displace native vegetation, reducing habitat for wildlife and native plants.
  • Draws pollinators away from native plants.

Current Management in Alberta

  • Control of Himalayan balsam can be difficult, especially once well established. Methods for control or eradication by trained personnel include careful hand digging for isolated or small populations, repeated mechanical cutting, and chemical treatment. The objective for control is to repeatedly remove the plant before they set seed.

Related Information:

Pale Yellow Iris

Pale Yellow Iris

Place of Origin/When Introduced

  • Native to the Africa, Asia and Europe and was likely introduced to North America as an ornamental plant. Pale yellow iris has already been found in isolated locations in Alberta.

Habitat

  • Grows in wetlands or along waterbodies – it can grow in water up to 25cm deep.

Identification

  • Pale yellow iris leaves are long, dark green and sword-like with raised mid-ribs that are slightly off-centre; overlapping fan-like arrangement starting from the base.
  • Flowers are white to yellow with distinct purple to brown markings.
  • Flat brown seeds form in large, green triangular capsules.

Reproduction

  • It is able to reproduce both by seed, easily dispersed by water, and through thick rhizome (root) fragments and bulbs.

Issues

  • Pale yellow iris presents a human safety concern, as all parts of the plant are irritating to skin and poisonous to humans and animals if consumed.
  • Infestations can displace native vegetation and alter water quality, reducing habitat for fish, wildlife, and native plants.
  • Dense rhizome mats in irrigation ditches, channels, or stormwater management ponds can increase sedimentation, disrupt the flow and availability of water and change wetlands to dry environments.

Current Management in Alberta

  • Control of pale yellow iris can be difficult, especially once well established. Methods for control or eradication by trained personnel include careful hand digging and benthic barriers for isolated or small populations, repeated mechanical cutting, and chemical treatment. Burning is not recommended, as regrowth is expected.
  • Care must be taken with hand digging and cutting to ensure all plant fragments are removed and disposed of. Fragments and seeds can drift with water movement and result in new infestations.

Related Information

Purple Loosestrife

Purple Loosestrife

Place of Origin/When Introduced

  • Native to Asia and Europe and was likely introduced to North America as an ornamental plant. Purple loosestrife has already been found in sporadic locations in Alberta. In the 1990s, a purple loosestrife eradication program in Alberta was successful in reducing the majority of locations in the province.

Habitat

  • Prefer to grow in moist, highly organic soils and neutral to alkaline pH.

Identification

  • Purple loosestrife leaves are slightly hairy, lance-shaped, and can be opposite or whorled.
  • Flowers attach closely to the square, woody stem in a tall vertical spike; petals are pink to purple surrounding a yellow centre.

Reproduction

  • It reproduces primarily by seed, producing more than two million seeds per plant annually but can also spread through stem cuttings and root fragmentation.

Issues

  • Purple loosestrife infestations can displace native vegetation and alter water quality, reducing habitat for fish, wildlife, and native plants.
  • Dense, tall stands in irrigation ditches, channels, or stormwater management ponds can disrupt the flow and availability of water and eliminate open water.

Current Management in Alberta

  • Control of purple loosestrife can be difficult, especially once well established. Methods for control/eradication by trained personnel include: careful hand-digging for isolated or small populations, repeated mechanical cutting, and chemical treatment.
  • Care must be taken with hand digging and cutting to ensure all plant fragments are removed and disposed of. Fragments and seeds can drift with water movement or animal dispersal and result in new infestations.

Related Information

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

 

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Updated: Jul 9, 2018