Flowering rush

Scientific Name: Butomus umbellatus

Jack Randall, Bishop Museum, HawaiiCopyright Info

Identification: Flowering rush is a tall perennial plant. Its sword-shaped leaves are triangular in cross-section and arise from a low, horizontal stem. It blooms from July to September. The flower stalks are umbrella-shaped clusters of many white to pink three-petal flowers. This species is also known as grassy rush and water gladiolus.

Size: This plant grows up to 5 feet (1.5 m) high with leaves up to 3 feet (1 m) long. Flowers are approximately 1 inch (2-3 cm) across.

Native Range: This species is native to Africa, Asia, and Eurasia.

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Butomus umbellatus are found here.

Full list of USGS occurrences

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Indiana195219631St. Joseph
Michigan1905201823Au Sable; Betsy-Chocolay; Cass; Cheboygan; Clinton; Detroit; Huron; Kalamazoo; Kawkawlin-Pine; Lake Erie; Lake Huron; Lake Michigan; Lake St. Clair; Lone Lake-Ocqueoc; Lower Grand; Ottawa-Stony; Pere Marquette-White; Pigeon-Wiscoggin; Raisin; Saginaw; Shiawassee; St. Clair; St. Joseph
New York1929201415Chaumont-Perch; Great Lakes Region; Headwaters St. Lawrence River; Lake Champlain; Lake Ontario; Mettawee River; Niagara; Northeastern Lake Ontario; Oak Orchard-Twelvemile; Oswego; Raisin River-St. Lawrence River; Richelieu River; Salmon-Sandy; Seneca; St. Lawrence
Ohio193320198Ashtabula-Chagrin; Black-Rocky; Cedar-Portage; Cuyahoga; Lake Erie; Ottawa-Stony; Sandusky; Tiffin
Pennsylvania194120152Chautauqua-Conneaut; Lake Erie
Vermont192720073Lake Champlain; Mettawee River; Otter Creek
Wisconsin197520178Fox; Lake Michigan; Lake Winnebago; Oconto; Peshtigo; Pike-Root; Upper Fox; Wolf

Table last updated 12/5/2019

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Means of Introduction: This plant was first observed in North America in 1897, and it was first collected from the St. Lawrence River in 1905. It is now found in 16 states in the northern and northeastern United States, as well as six Canadian provinces. It is widespread in the Great Lakes region and is actively expanding.

Status: Flowering rush was intentionally brought to North America from Europe as an ornamental plant. It has been introduced to new waterways by garden planting and can also be spread when plant fragments cling to boats and recreational equipment. In addition, muskrat use parts of the plant and contribute to its local spread. Once introduced, it spreads locally through growth of horizontal stems, fragmentation of the root system, and transport by water and ice movements.

Remarks: It is illegal to purchase flowering rush in some states because control is very difficult. Herbicides easily wash away from its narrow leaves, and cutting alone does not eliminate the plant because it can grow back from the roots. Care must be taken to remove cut pieces from the water so that they don’t float to new locations where they can sprout new plants.

Author: Illinois-Indiana Sea Grant

Contributing Agencies:
NOAA Sea Grant GLRI Logo

Revision Date: 9/25/2012

Citation for this information:
Illinois-Indiana Sea Grant, 2019, Flowering rush: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatlakes/FactSheet.aspx?SpeciesID=1100&Potential=N&Type=1&HUCNumber=All%20Great%20Lakes, Revision Date: 9/25/2012, Access Date: 12/5/2019

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.