Flowering Rush Facts
Appearance: Perenial aquatic herbaceous plant. It grows 1-4' high on an erect stem along shores in shallow water.
In deeper water it grows submerged without producing flowers. Flowering rush is very difficult to identify when not in flower. It closely resembles many native shoreland plants, such as the common bulrush.
Leaves: Leaves are sword-shaped,
triangular in cross section.
Flowers: Pink flowers are arranged in umbels (umbrella-shaped).
Seeds: Populations in the eastern U.S. produce seeds. Only one Minnesota population (Forest Lake) produces viable seeds.
Roots: Reproduces by vegetative spread
from its rootstock in form of bulb-lets.
Both seeds and bulb-lets are dispersed by water current.
Flowering Rush Rhizome
History in Pelican River Watershed
Flowering Rush was introduced before 1976 as an ornamental planting in Lake Curfman (Deadshot Bay).
- 1978 - Found along South Shore Drive
- 1980 - Established vegetation beds along the Flats
- 1982 - Plants are found along the Detroit Lakes city beachfront area
- 1985 - North and East Shore Drive are infested with Flowering Rush
- late 1980's - Mechanical harvest operation reaches its height
- 1994 - Flowering rush has established throughout Detroit, Sallie, and Melissa Lakes
- 2005 - Chemical Treatment begins
- 2005 - Mill Pond is infested
- 2008 - Buck Lake infested
- 2010 - Research project with Mississippi State begins
- Current - Dramatic reductions within treatment areas continue
Progression of Flowering Rush in Big and Little Detroit Lake from Curfman
Flowering Rush Research and Treatments
In 2010, the District gathered experts from around the US to form a collaborative effort to research the growth cycle, habitat, and herbicide options to better understand Flowering Rush and develop better management strategies. The partnership included the Pelican River Watershed District, Mississippi State University Geosystems Research Institute (GRI), Concordia College (Moorhead, MN), US Army Corps of Engineer Research and Developments Center (USACERDC), and the Minnesota Department of Natural Resources - Ecological and Water Resources Division.
In order to most effectively reduce Flowering rush populations, submersed (below water surface) flowering rush was targeted for the treatment research project. The growth cycle and habitat studies were used to refine herbicide application timing and water depths for treatments. Small-scale herbicide trials and an in-lake dissipation study were conducted in 2010-11. Based upon these promising results, in 2012, the first operational-scale of Flowering rush in-lake treatments were conducted on Detroit, Curfman, Sallie, and Melissa lakes. In 2013, the treatment areas were expanded due to the significant reduction of below surface plants and roots following treatment with limited impact on native plant species.
Flowering Rush Reports
2014 Flowering Rush Research Report
Mississippi State's Geosystems Research Institute has released the report for the 2014 Flowering Rush study. The study was a collaborative effort between the Dr. Gray Turnage, Dr. John Madsen, and the Pelican River Watershed District staff. The report is available to download.
2015 Flowering Rush Treatment Areas
Flowering Rush Treatment and Research is complete for the 2015 season. The plant samples from the first year of the "maintenance" phase of research are currently being analyzed. We expect to have the full report complete in the spring of 2016. The thresholds for where and when treatments occurred can be found in the 2015 Pre-Treatment Summary.
2015 Pre-Treatment Summary, Mississippi State University