Connect with us


Report an Invasive Species

Flowering rush

Flowering rush

Flowering rush

(Butomus umbellatus )

Priority: -  Contain

Tags: Aquatic | EDRR

Identification and Reproduction

Identification:

  • Flowering rush is an aquatic perennial that resembles native grasses.
  • It is most notable during its flowering stage; July through September. Plants will only produce flowers when situated in shallow water or on dryer sites. 

  • Flowers grow in an umbrella shaped cluster. Each individual flower segment is made up of 3 green sepals and 3 white to pink petals. 

  • Green stems, appearing like bulrushes and triangular near base. 

Reproduction:

  • It spreads through seeds as well as by underground stems and rhizomatous roots.
  • The root fragments may break off and float in waterways to re-establish elsewhere.
  • Animals may use pieces of the plant for their habitats, furthering its spread.
  • Fragments are also easily broken and transported from boat users.

Habitat & Ecology

  • This plant thrives in freshwater wetlands; commonly found along edges of rivers and lakes. 
  • It can also grow suspended in water up to 3-6 m deep. 
  • Flowering rush has already invaded the Great Lakes region and has caused significant impacts. 
  • Waterbodies that flucutate in water levels are vulnerable to flowering rush infestations. When water levels are low and soil is exposed this allows flowering rush to spread further. 

Impacts

Social: 

  • Dense patches may block recreational users. 
  • Infestations can also obstruct irrigation ditches. 

Ecological:

  • As they invade, they will crowd out native plants, disrupting the natural food chain. 
  • Alters water quality and will interfere with native fish and wildlife habitat. 

Management

Prevention is a high priority for this plant. Always clean, drain, and dry aquatic equipment like boats or canoes before transferring from one body of water to another. Never grow or intentionally transport this plant, or dispose of aquarium plants in waterways or down the drain.

For alternative planting options to flowering rush download the ISCBC's Grow Me Instead brochure (pg. 27 and 28).

Mechanical/Manual Control:

  • Cutting plant stems right below the water surface will help summer flowering; minimizing the risk of spread. Cutting will not kill the plants, as the roots will still survive.

  • Hand digging may be effective on isolated patches of flowering rush. It is best to remove isolated patches as it is often hard to differentiate flowering rush from native rushes and even sedges. Digging should be done with extreme caution as any broken fragment will reproduce. 

Resources

Download the Alberta Invasive Species Council's Factsheet on Flowering Rush here

Header photo (Ar Herrmann).