Flowering rush

Flowering rush (Butomus umbellatus) can reduce irrigation water availability and impede aquatic activities like boating or swimming.

Place of origin

Originally from Eurasia, flowering rush (Butomus umbellatus) it was introduced as an ornamental garden plant in the 1890s. This invasive aquatic plant is now found across Canada and the United States.


Can grow as an emergent plant along shorelines or partially submerged in lakes and rivers up to 4 m in depth.


  • A perennial, surviving winters and droughts.
  • Cross section of leaves is triangular, while the flowering stem is round.
  • Easiest to identify when flowering in summer months. Each umbrella-shaped cluster has whitish pink petals. 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.).


  • Can reproduce by root system fragments or rhizome buds called bulbils.
  • Seed production is yet to be observed in North American populations.


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

Current management in Alberta

The Alberta government has partnered with several organizations to study flowering rush eradication methods on Lake Isle and Chestermere Lake. The following methods have all been tested in Alberta:

  • Bottom barriers
  • Diver assisted suction harvesting
  • Hand digging
  • Herbicide treatments
  • Mechanical harvesting

Hand digging and herbicide treatments are the most feasible treatments, but they have their limitations with effort and approvals.

Herbicide applications to decrease the population and density of flowering rush were also used in Buffalo Creek near Innisfail.


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