By Kallum McDonald

Aquatic invasive species (AIS) pose a serious threat to lakes, rivers, and other waterbodies because of their ability to outcompete native species, alter hydrology, disrupt aquatic food webs, and hinder aquatic recreation.

Flowering Rush is a prohibited invasive species under both the Weed Control Act and the Fisheries (Alberta) Act.

Recently, Alberta Environment & Protected Areas received the first report of Flowering Rush (Butomus umbellatus), a prohibited aquatic invasive plant, in the Red Deer River itself. There is a known infestation of Flowering Rush in Buffalo Creek near Innisfail (also within the Red Deer River watershed) and has been receiving control for several years. Another known infestation of Flowering Rush is at Lake Isle (west of Edmonton), which has undergone 3 years of chemical treatment, with strong results. The Bow and South Saskatchewan Rivers are also heavily infested.

Flowering Rush has long, thin leaves that appear similar to shoreline grasses and native reeds to the untrained eye. Here is how to identify Flowering Rush:
• Leaves 3-sided (triangular in cross section), often purplish-red coloration in the lower portion.
• Leaves can be fully submerged or emerge 2-3 ft above the water’s surface.
• Flowers arranged in umbrella-like clusters, bright pink (3 petals, 3 sepals), and borne on tall stalks.
• Blooms July-August. No native aquatic or shoreline plants in Alberta have 6 pink petals.