Stop the Spread-Flowering Rush
Trout Unlimited Canada’s Stop the Spread campaign focuses on actions that Canadians can take to prevent the spread and impact of aquatic invasive species and pathogens that threaten Canada’s fisheries. There are a number of invasive species threatening Canada’s water. Meet an invasive that you might not associate with the potential to damage our water and fish habitat, flowering rush.
L. Gillespie, Town of Innisfail
Identification: Flowering rush, a perennial aquatic species, has spongy and compressible triangular leaves and a round stem from which 2-2.5 cm diameter pink flowers grow. Twenty to fifty flowers can grow from a single stem with each flower capable of producing up to 1200 seeds. Fowering rush can grow as an emergent plant in waters up to 3 metres deep within lakes and slow moving streams or as a submerged plant in waters 3 to 6 metres deep. Identification of this invasive species is easiest while in bloom.
Sources of Introduction:
Flowering rush originated from Eurasia (Europe and Asia) and like many invasive plants, was likely introduced to North America an ornamental plant; in this case, for water gardens. Observations of this invasive species were first recorded in 1897 on the St. Lawrence River. Since then, flowering rush has been recorded in Canada in every province with the exception of Newfoundland and the territories.
Photo Credit: Ben Legler
Impact to the Environment: There are two varieties of the flowering rush – a sterile and a fertile variety. Fertile plants can reproduce by four different methods making flowering rush extremely prolific. Sterile plants can also spread when buoyant fragments of their root system establish themselves within sparsely vegetated shoreline soils of lakes, wetlands, or slow moving streams. Waterbodies with fluctuating water levels are particularly susceptible because exposed, unvegetated soils are the perfect place for flowering rush to establish. Like many invasive species, flowering rush competes with native shoreline vegetation and can displace these more desirable plants.
Why Should We Care? Chemical and mechanical methods to control flowering rush have proven to be ineffective or limiting, so prevention of its spread is imperative. Flowering rush can:
Grow prolifically in irrigation ditches reducing water flow and increasing maintenance costs
Colonize previously open-water areas of lakes and slow moving streams, impacting recreational activities by intertwining boat propellers and reducing angling opportunities.
Support habitat for the great pond snail which hosts the parasite that causes swimmer’s itch.
Adversely impact native fish species, specifically those adapted to open water habitats such as bull trout and cutthroat trout, by forming dense stands and limiting spawning areas.
How Can You Stop the Spread?
Learn to identify flowering rush.
Do not use flowering rush in landscaped water gardens.
Clean all recreational equipment (boats, trailers) and fishing gear prior to leaving any waterbody and dispose of any plant material in the garbage.
Talk to and inform others about the impacts of flowering rush and other invasive species.
Support Trout Unlimited Canada’s Stop the Spread program.
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