COMMON NAME

Flowering rush

FULL SCIENTIFIC NAME

Butomus umbellatus L.

FAMILY NAME COMMON

Flowering rush family

FAMILY SCIENTIFIC NAME

Butomus umbellatus

IMAGES

Flowers	Habit	Flowers
Fruit	Incursion	Roots
Habitat

NOMENCLATURE/SYNONYMS

Synonyms: Butomus umbellatus f. vallisneriifolius (Sagorski) Gluck

DESCRIPTION

Botanical Glossary

Butomus umbellatus is a perennial, aquatic herb that grows from a fleshy rhizome on freshwater shorelines. It can be found in water several meters deep, and its flowering stem can reach up to 1 m (3.3 ft.) above the surface of the water. The 0.6-0.9 m (2-3 ft.) long ensiform leaves can be erect or floating on the water's surface. The leaves are three angled, fleshy and have twisted ends. The plants flower from the summer to the fall depending on the depth of the water. The flowers are arranged in a bracted umbel. The bracts are purple-tinged, and numerous flowers are on long, slender ascending pedicels. The petals and sepals are 3-merous and are 2-2.5 cm (0.8-1 in.) in diameter. They can be white to deep pink, to purplish brown in color. The submersed form of this plant does not have flowers, and has narrow, long thin leaves. The flowers produce beaked fruits that are dark brown, 1 cm (0.4 in.) long, and split at maturity to release the seeds. Often the plant does not flower (as is the case with some populations in Connecticut), which makes its identification more difficult. Page References Bailey 131, Crow & Hellquist 3, Fernald 92, Flora of North America 4, Gleason & Cronquist 632, Holmgren 602, Magee & Ahles 129, Newcomb 118. See reference section below for full citations.

SIMILAR SPECIES

Sparganium spp. (Bur-reeds) The leaves of Butomus umbellatus and Sparganium spp. look similar. However, when Butomus umbellatus is in flower they are easily told apart.

REPRODUCTIVE/DISPERSAL MECHANISMS

The seeds of Butomus umbellatus float and are dispersed by water. The plant also spreads vegetatively its rhizome.

DISTRIBUTION

Butomus umbellatus is native to east Asia. In Canada it is established most prominently along the St. Lawrence River in Ontario and Quebec. In the United States it is also established in the St. Lawrence River valley, and in the states of New York, Pennsylvania, Ohio, Michigan, Wisconsin, Indiana, Illinois, Minnesota, North Dakota, South Dakota, Nebraska, Montana and Idaho. In New England it occurs in Maine, Vermont and Connecticut.

HISTORY OF INTRODUCTION IN NEW ENGLAND

Butomus umbellatus was first observed in 1897 in LaPrairie, Quebec (near Montreal, Canada). It was first collected in 1905 from this same location. In 1929, the plant was collected near Lake Champlain, NY. The first collection in New England was in the same year in two counties in Vermont. By the 1950s, the plant was solidly established along the St. Lawrence River. In Connecticut, it was first collected in 1943 in New Haven. There were also collections made in 1978 and 1992. It was noted that the plant was being established via rootstocks in 1930 and seeds in 1940 in New York.

HABITATS IN NEW ENGLAND

Butomus umbellatus is mostly found on shores of lakes, ponds and riverbanks. It is intolerant of salt or brackish water.

THREATS

Butomus umbellatus can displace native riparian vegetation, and can be an obstacle to boat traffic. Its very wide range of hardiness (zones 3-10) gives it the potential of being widely invasive in the United States.

MANAGEMENT LINKS

Minnesota Department of Natural Resources

DOCUMENTATION NEEDS

Documentation required: Herbarium specimen or mounted snippet of the rhizomes or inflorescence.
Best time for documentation: Spring, summer.

ADDITIONAL INFORMATION

Integrated Taxonomic Information System
Has general taxonomic information about the species.

The PLANTS Database
General information including a map

Canadian Wildlife Service

Center for Aquatic and Invasive Plants

Northern Prairie Wildlife Research Center
Description and map for prairie states

Global Invasive Species Database
Comprehensive information

Invasive Plants of Wisconsin

Flora of North America

Bailey, L.H.  1949.  Manual of Cultivated Plants.  Macmillan, New York.

Crow G.E. and C.B. Hellquist. 2000. Aquatic and Wetland Plants of Northeastern North America. Vol #2. University of Wisconsin Press, Madison.

Fernald, M.L.  1950.  Gray's Manual of Botany 8th edition.  American Book Company, New York.

Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. Volume #1. Oxford University Press 

Flora of North America Association ed. 2000.  Flora of North America vol. 22. Oxford University Press, Oxford, New York.

Gleason, H.A. and A.C. Cronquist.  1991.  Manual of Vascular Plants of the Northeastern United States and Adjacent Canada. 2nd ed.  New York Botanical Garden, Bronx, New York.

Holmgren, N.H. 1998. Illustrated Companion to Gleason and Cronquist's Manual.  New York Botanical Garden, Bronx, New York.

Les, D.H. and L.J. Mehrhoff.  1999.  Introduction of nonindigenous aquatic vascular plants in southern New England: a historical perspective.  Biological Invasions 1:281-300.

Magee, D.W and H.E. Ahles. 1999.  Flora of the Northeast. University of Massachusetts Press, Amherst.

Newcomb, N. 1977.  Newcomb's Wildflower Guide.  Little Brown, Boston.

USDA, NRCS.  2001.  The PLANTS Database, Version 3.1. (http://plants.usda.gov).  National Plant Data Center, Baton Rouge, LA 70874-4490 USA.