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Flowering Rush

(Butomus Umbellatus L.)

Common Names

grassy rush, water gladiolus


Flowering rush is an aquatic perennial that can reach heights of five feet tall. Stems are erect and triangular. Leaves are also sword-like and triangular and may end with spirals. The root system is extensive and often remains submerged in water. The roots also form unique bulb-let rhizomes. If the plant flowers, the flowers are distinctive in that they are umbrella-shaped and pink and white in color. Each flower has three white to pink petals and flowers bloom from June to August, but will not flower if the plant is located in deep water.  If the plant does not flower, it is very difficult to differenciate between the invasive and natives such as common bulrush. Six pods  with long beaks develop when mature; each pod contains numerous seeds. Flowering rush reproduces by seed and by root.

Key Features

The umbrella-shaped pink and white flower and the bulb-lets that are formed on the extensive root system.


Flowering rush requires wet soil and full sun. It will not grow in shaded areas. It is found in the riparian areas including water courses and wetlands such as muddy shores of shallow water, ditches, marshes, lakes, or streams. It grows well in a variety of soil types.

Currently found in the following counties:

Flathead, Lake, Missoula and Sanders


Interesting Facts

Bark from other plants and flowering rush were used at one time to aid in the elimination of worms from horses and cattle. The roots of flowering rush have been said to be roasted and eaten in Asia.

Commonly Confused Plants

  • The leaves of Butomus umbellatus and Sparganium spp. look similar. However, when Butomus umbellatus is in flower they are easily told apart.
  • Common Bulrush

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Photo credits:Photo Credits: Christian Fischer; ©Gary Fewless, Cofrin Center for Biodiversity, University of Wisconsin-Green Bay,; Peter Rice