A program of the Bonner Soil and Water Conservation District, the Lake Assist program provides assistance to Bonner County residents on water quality concerns and suggestions on how to reduce pollutants to our abundant lakes, rivers, streams and groundwater.
Lake Assist
Flowering Rush
(Butomus umbellatus)
Flowering rush is an exotic plant that was likely introduced to North America from Europe as a garden ornamental. Once in a watershed, it spreads locally by rhizomes and root fragments, transported by animals, boats, flowing water and ice movement.
Flowering rush grows as an emergent plant along shorelines and as a submersed plant in lakes and rivers. This plant can form dense stands, which interfere with lake use and crowd out native vegetation. Flowering rush can create a marsh out of a bay in very short order.
Protecting native riparian or shoreline plants is an important way to help keep flowering rush out of your shoreline. It likes exposed, bare soils so keep your native vegetation intact and dense. It is very difficult to control and eradicate flowering rush. Inappropriate control methods can worsen the flowering rush problem. Hand digging can be used to remove small isolated plants, but use extreme care to remove all root fragments as the rhizomes break easily risking further spread. Any disturbance to the root system will cause small reproductive structures on the roots to break off and spread to other areas. Methods such as raking or pulling only disturb the root system and are not recommended. If this method is used, dispose of plants far away from shoreline and thoroughly dry all the flowering rush plant once removed from the water. Any amount of moisture will aid its survival.
It is very difficult to kill flowering rush with herbicides. Herbicides are easily washed away from the narrow leaves of this plant. At this time, no specific herbicide has been successful at controlling flowering rush long term.
Identifying Flowering Rush
Flowering rush looks very similar to native rushes that occur in wetland areas. It is easy to identify by the stem which is triangular in cross section (Figure 9-15). This is easy to determine by pinching stem in half and by looking at the root system(9-16). Most flowering rush plants do not flower.
· The stems are green and triangular in cross section.
· Plants can be found growing along the shore and submerged in water with erect leaves, reaching to about 3 feet in height.
· When plant grows beyond being submerged, it will often lay limp on the surface of the water.
· When first emerging in spring, new leaves appear purple and are difficult to see in mud.
