Flowering Rush (Butomus umbellatus)

Flowering Rush family (Butomaceae)

Description

Flowering rush is a perennial, aquatic, herbaceous plant that usually occurs on pond, lake, and river shorelines and in shallow water, but can grow in water to a depth of 8 to 9 feet.  Distinctive features include its 2-3 foot long linear leaves, which are triangular in cross-section, and its umbrella-shaped clusters of white to pink flowers (0.8 to 1.0 inches in diameter) on top of stems that reach 3 to 4.5 feet in height.  Each flower has 3 petals and 3 sepals; the petals and sepals are almost identical, so the flowers appear to consist of 6 petals.   The plant flowers from June to early fall.  The fruits are brown, beaked capsules that contain many tiny seeds. 

Reproductive/Dispersal Methods

The seeds of flowering rush float and are spread by water.  It also forms new plants from rhizomes and root fragments.

Similar Species

The plant’s flowers are distinctive, but the leaves look like those of other aquatic species, such as bur-reeds (Sparganium spp.) and bulrushes (Scirpus spp.).  Individuals that grow in deep water consist only of leaves, and are difficult to distinguish from other aquatic plants.

Impacts

Flowering rush displaces native vegetation in marshes and shallow ponds.  Dense stands can interfere with boat traffic.

Distribution

This Eurasian species has become established in much of Canada and the northern United States.  It is widespread in the Lake Champlain area of Vermont and also occurs in Connecticut and Maine. There is one known Massachusetts occurrence, in Middlesex County.

Sources and Links

Invasive Plant Atlas of New England (IPANE)

http://nbii-nin.ciesin.columbia.edu/ipane/icat/catalogOfSpecies.do

Global Invasive Species Database

http://www.issg.org/database/species/ecology.asp?si=610&fr=1&sts=sss&lang=EN

Invasive Plant Atlas of the United States

http://www.invasiveplantatlas.org/subject.html?sub=5219

MinnesotaSeaGrant:

http://www.seagrant.umn.edu/ais/floweringrush

New Invasive Plants of the Midwest Fact Sheet

http://www.mipn.org/Midwest%20Invasives%20Fact%20Sheets/PDF/floweringrush.pdf

USDA Plants Database

http://plants.usda.gov/java/profile?symbol=BUUM