Flowering Rush
Butomus umbellatus
Washington State Classification
Class A — Eradication Required Statewide
Flowering rush is an invasive aquatic plant in the northeast U.
Quick Reference
Identification
Growth Habit
Flowering rush is an emergent, aquatic, perennial that grows in a range of fresh water habitats.
Leaves
It has a rhizome that produces thin, upright leaves that may be twisted in growth and reach 3 feet or more in length. They can be emergent, submersed or floating. Leaf bases are triangular in cross-section.
Flowers
Plants have a cylindrical stalk, up to 5 ft tall, ending in a flat-topped flower cluster with individual flower stalks originating from a common point of 20 to 50 light pink flowers. Flowers have three sepals, three petals, nine stamens and pink pistils.
Fruit & Seeds
The seeds are very small and are in follicles.
Impact
Flowering rush is an invasive aquatic plant in the northeast U.S. and has a limited distribution Washington. It is an aggressive colonizer and can spread by seed, bulbils and rhizome fragments. It can be difficult to control and research continues on control options.
Ecology & Spread
Habitat
It’s considered a wetland obligate and grows in only freshwater habitats. It roots in the mud and grows in shallow waters (to a depth of about 9 feet) in a variety of wetlands, particularly along the shoreline of lakes and slow moving rivers. Please click here to see a county level distribution map of flowering rush in Washington.
Spread Mechanisms
Reproduction
Flowering rush reproduces both by seed and clonally through the production of numerous vegetative bulbils on both the rhizomes and inflorescences and by small scale rhizome fragmentation.
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Control Methods
Mechanical
- Digging or suction dredging by hand may be a control option for isolated or individual plants in areas of low density populations. To be successful, the entire rhizome system must be removed without dislodging the rhizome bulbils. Even a slight bottom disturbance can cause the rhizome bulbils to release. Land disposal of plant material is necessary. No plants or sediments can be returned to the water.