Flowering Rush (Butomus umbellatus)


Common names:

Flowering rush, grass rush, water gladiolus

Scientific Name:

Butomus umbellatus


Flowering rush is an aquatic perennial plant in the Butomaceae family. Leaves are thin, and either straight or slightly twisted, up to 40 inches long, and have a triangular cross-section at the base. When the plant is submerged the leaves are flexible, and when emerging along the shoreline, they are more stiff. Flowers have 3 large pink petals (with three sepals below that look like petals), and grow in flat-topped clusters of 20-50 on tall cylindrical stalks. It has fleshy rhizomes that trail along the ground (??). It was introduced as an ornamental and is sometimes still sold for water gardens. It spreads mostly through rhizome fragments or small bulbils that detach and disperse through the water, though some varieties also produce seeds.

Life cycle:


Height of mature plants

Up to 5 feet

Flower color:

Light pink

Bloom time:

June – August


While not a true rush, it looks similar to many other rushes and bulrushes


Flowering rush requires wet soil and sunshine. It can be found in wetlands, irrigation ditches, shorelines, and along slow-moving streams and rivers, and it can grow in water up to 9 feet deep. It often grows in areas with fluctuating water levels and can tolerate a wide variety of temperatures.


Flowering rush is an aggressive colonizer that can out-compete native wetland and shoreline vegetation. It can clog slow moving waterways and impede boat travel and fishing along shoreline, thus degrading both their recreational and ecological value. As an aquatic plants that spreads vegetatively, it is difficult to control, and can be easily spread by waterfowl, wildlife, and boaters.

Noxious Weed Listing:


Northern Africa, Asia, and Europe


Oregon Noxious Weed Profile
Washington Noxious Weed Profile
King County Noxious Weed Profile
Invasive.org profile


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