Vectors of spread:
General: Perennial, aquatic macrophyte. Flowering Rush has two plant forms: emerged and fully submerged. It is most distinguishable by its flowers, however, most plants may not produce any flowers at all.
Flowers: Around 20 – 50 flowers form an umbrella-shaped cluster at the end of each stem. Each flower has three pinkish-white petals, three sepals, and red anthers. Flowering Rush is most distinguishable by its flowers, however, it may or may not produce any.
Stem: Stems are green, resemble Bulrush, and can grow up to 1.5 m tall.
Leaves: Thin, straight, sword-shaped leaves that are dark green and have a triangular cross-section. When broken, the leaves also have cob-web like white filaments connecting the two segments. The leaves of a fully submerged plant are flexible and float at the surface. The leaves of an emerged plant are stiff and upright.
Fruits: Has follicle fruits that contain many seeds. The seeds are straight and lined.
Common Bulrush (Typha artifolia) : Common Bulrush, often referred to as Common Cattail, is a native plant to British Columbia that closely resembles a Flowering Rush plant but that does not possess any flower clusters.
Common Bulrush is commonly identified by its large cylindrical seed pod, found on the female plants. Plants are 0.9 – 2.7 m, and leaves are large, thin and tapered. Similar to Flowering Rush, Common Bulrush grows in extremely moist environments including freshwater, marshes and shorelines.
Habitat and Origin
Flowering Rush originates from Europe and was most likely introduced to North America as an aquatic ornamental plant. It is an extremely aggressive spreader that grows in a variety of aquatic ecosystems such as along the shorelines of ponds, small water bodies, wetlands, and previously vegetated areas. The emerged plants can be found at the shorelines of these water bodies. Flowering Rush often prefers shallow waters but can survive water up to 6 m deep.
Propagation and Vectors of Spread
Flowering Rush reproduces mainly by the rhizome and root bulblets. The growing tips and fragments of the rhizome can form new plants. Pea-sized root bulblets (bulb-like plant sprouts), may be present on the rhizome or at the base of the plant. Only some Flowering Rush plants reproduce by seed.
The long-distance dispersal of Flowering Rush can be attributed to nursery sales and its use as an ornamental plant in aquatic gardens. Once introduced to an area, local dispersal can occur via water, human recreation, and the improper disposal of garden materials. Seeds, root fragments, and root bulblets can detach from the plants and disperse to new locations in the current. Flowering Rush is considered a pioneer species, as it invades areas lacking plant diversity with ease.
Ecological and Economic Impacts
Crowds out native vegetation and provides cover and nesting habitat for invasive fish species such as the Northern Pike, Walleye, Smallmouth Bass, and Largemouth Bass, thereby altering natural ecosystems.
The presence of Flowering Rush has been linked to cases of Swimmer’s itch, as it provides ample habitat for the Great Pond Snail, which hosts parasites that carry Swimmer’s itch.
Dense stands impede the use of shallow waters for boating and other recreational activities as well as irrigation systems.
What Can I Do?
Flowering Rush has currently been found at only one site in Whistler, and three in all of British Columbia. The best approach to controlling the spread of Flowering Rush is PREVENTION.
Learn to identify Flowering Rush: use the images presented in this profile page to learn how to identify Flowering Rush.
What to do if you spot it: You can report any Flowering Rush sighting by clicking here.
- Always clean, drain, and dry boats and equipment before leaving any water body (to avoid spreading floating seeds or plant parts).
- Take caution when transporting your boat or other equipment from one province to another.
- Regularly monitor any property for Flowering Rush and control new infestations.
- Be PlantWise and choose alternative non-invasive species when selecting plants for a garden.
- Minimize soil disturbances near Flowering Rush plants.
- Ensure plants (particularly flowering heads or root fragments) are bagged or covered to prevent spread during transport to designated disposal sites (e.g. landfill).
- Maintain riparian and aquatic environments in a healthy condition to ensure a productive natural plant community.
- Plant Flowering Rush in aquatic gardens, no matter how well-contained its enclosure may seem.
- Purchase Flowering Rush at nurseries, garden stores.
- Move water-crafts from water bodies where Flowering Rush has been reported to water bodies where Flowering Rush is not present without performing the Clean, Drain, Dry method
Flowering Rush is very difficult to control.
- Mechanical methods of control (cutting, digging, etc.) can be effective at decreasing abundance, however, these methods are problematic, as they can cause the spread of seeds, root fragments, and root bulblets.
- Herbicide treatment is not possible at most sites, due to the plant’s aquatic habitat.
- In any case, herbicide control is challenging and complex, and should not be attempted without seeking more information from the BC MFLNRORD.
- There are currently no biocontrol agents available for this species in BC.
Due to its limited distribution in BC, Flowering Rush is part of the Early Detection Rapid Response program in BC. SSISC is working with the BC Government to control the Whistler site.
- Alberta Invasive Species Council, Flowering Rush, https://abinvasives.ca/fact-sheet/flowering-rush/
- Britannica Encyclopedia, Flowering rush, https://www.britannica.com/plant/flowering-rush
- CABI, Biological Control of Flowering Rush, https://www.cabi.org/projects/biological-control-of-flowering-rush/
- Central Kootenay Invasive Species Society, Flowering Rush, https://ckiss.ca/species/flowering-rush/
- Electronic Atlas of the Flora of British Columbia, Butomus umbellatus, http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Butomus%20umbellatus
- Fall Wildflowers of New England, Common Cattail, http://www.bio.brandeis.edu/fieldbio/Wildflowers_Kimonis_Kramer/PAGES/COMMONCATTAIL_PAGE_FINAL.html
King County, Flowering-rush Identification and Control, https://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/flowering-rush.aspx
- Invasive Species Centre, Flowering Rush, https://www.invasivespeciescentre.ca/invasive-species/meet-the-species/invasive-aquatic-plants/flowering-rush/
- Invasive Species Council of British Columbia, Flowering Rush, https://bcinvasives.ca/invasives/flowering-rush/
- Manitoba Invasive Species Council, Flowering Rush, http://invasivespeciesmanitoba.com/site/index.php?page=flowering-rush-2
- Minnesota Department of Natural Resources, Flowering Rush, https://www.dnr.state.mn.us/invasives/terrestrialplants/herbaceous/floweringrush.html
- Ontario Invasive Plant Council, Flowering Rush Best Management Practices in Ontario, https://www.ontarioinvasiveplants.ca/wp-content/uploads/2021/01/FloweringRush_Edn1.0_March2020.pdf
- Washington State Noxious Weed Control Board, Flowering Rush, https://www.nwcb.wa.gov/weeds/flowering-rush