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Flowering rush

(Butomus umbellatus)

Photo of flowering rush
Photo credit: Kitty Kohout

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


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.
Overview map of flowering rush classification in WI
Restricted (orange) counties

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 [PDF] 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 the 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.


See the reported locations of flowering rush in Wisconsin.

Do you know of additional populations? 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: