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Flowering rush
(Butomus umbellatus)

Emergent aquatic perennial that can grow to be 1-5’ tall. It can also survive in water as deep as 10’.


Regulated areas of flowering rush
This species is listed as Restricted(orange counties)

Other names for this plant include:

  • Common names: grassy rush, water-gladiolus

Ecological threat:

  • Marshes, backwaters, and along shorelines; forms dense colonies and crowds out native species.

Classification in Wisconsin: Restricted

Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. The recommendation for flowering rush was based upon this literature review developed by the department.


Leaves: These 3-sided leaves are stiff, narrow and triangular in a cross-section. They get to be 3’ tall and 0.5” wide. May remain submerged if water is too deep, but are limp.

Flowers: White to light pink-rose in color. Flowers have 3 petals, 3 sepals, and red anthers. Terminal umbels bloom June-August; rise above leaves. Will not emerge or flower if in deep water.

Fruits & seeds: Clustered follicles with long beaks containing many seeds that are generally not viable.

Roots: Rhizomes that aid in vegetative growth also produce small bulbs, or bulblets, that are easily dispersed by water.

Similar species: Bur-reed (Sparganium spp.) is another shallow-water emergent that is roughly the same height as flowering rush and also has similar leaves. However, bur-reeds have v-shaped leaves and the female flower parts look like small, spiked balls.


Counties in WI where flowering rush has been reported (as of April 2013). Both vouchered and unvouchered reports included.

Do you know of flowering rush locations? Send us a report.


Mechanical: Can be cut several times throughout the year below the water line. Small populations can be dug out making sure to get all of the root fragments.

Chemical: Some aquatic herbicides may control flowering rush infestations. Aquatic approved herbicides require a permit


View flowering rush pictures in our photo gallery!


Sources for content:

  • Czarapata, Elizabeth; Invasive Plants of the Upper Midwest: an illustrated guide to their identification and control. University of Wisconsin Press. 2005. Pg. 142-143

Links for More Information

Last revised: Friday May 31 2019