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      Butomus umbellatus (Photo: © Mandy Tu/The Nature Conservancy) - Click for full size   Butomus umbellatus (Photo: © John M Randall/The Nature Conservancy) - Click for full size   Butomus umbellatus (Photo: © John M Randall/The Nature Conservancy) - Click for full size   Butomus umbellatus (Photo: © Mandy Tu/The Nature Conservancy) - Click for full size
    Taxonomic name: Butomus umbellatus L.
    Synonyms:
    Common names: butome à ombelle (French), flowering rush, flûteau (French), grassy rush, jonc fleuri (French), water gladiolus
    Organism type: aquatic plant
    Butomus umbellatus commonly known as flowering rush, is a moderately tall, rush like perennial found on shores of lakes, ponds and riverbanks. It can tolerate water as deep or deeper than 2 metres, extending to the deepest range of emergent marsh species. Flowering rush can displace native riparian vegetation, and can be an obstacle to boat traffic. Once established, populations' increase and can persist indefinitely. Control of this species is very difficult, especially with herbicides because they easily wash away from the narrow leaves of this plant. Extensive physical methods of control must be employed to manage this invasive exotic. It can be spread over long distances by garden planting, and once established in a watershed it spreads locally by rhizomes and root pieces that break off. Muskrats use parts of the plant and contribute to its local spread. Boaters can also transport flowering rush on their equipment.
    Description
    Flowering rush is described as a moderately tall, rush-like perennial. Its leaves are basal originating from a stout rhizome that is stiff and erect when immersed or lax and floating when in deep water. The inflorescence is a many-flowered umbel borne on a scape 1 to 1.5m tall. The flowers are perfect, regular, 2-3cm across, and pink. There are 3 sepals, which are petaloid. There are 3 petals, 9 stamens, with elongate anthers. Flowering rush has 6 pistils that are simple, whorled, and united at the base. The fruit is an indehiscent, many-seeded capsule (USGS-NPWRC, 1999).
    Similar Species
    Sparganium spp.

    More
    Occurs in:
    lakes, riparian zones, water courses, wetlands
    Habitat description
    Flowering rush grows in marshes and can tolerate water as deep or deeper than that in which cattail is normally found (up to 2 metres), extending to the deepest range of emergent marsh species (Fewless, UNDATED). IPANE (2001) reports that, "B. umbellatus is mostly found on shores of lakes, ponds and riverbanks, and it is intolerant of salt or brackish water.
    General impacts
    IPANE (2001) reports that, "B. umbellatus can displace native riparian vegetation, and can be an obstacle to boat traffic. Its very wide range of hardiness (zones 3-10) makes it capable of being widely invasive in the United States." Fewless (UNDATED) states that, "Once established in a marsh, B. umbellatus populations increase and persist indefinitely."
    Uses
    Flowering rush tuber can be cooked. It should be peeled and the rootlets removed. The root can also be dried and ground into a powder; it can then be used as a thickener in soups etc, or be added to cereal flours when making bread. It contains more than 50% starch (Plants for a Future, UNDATED).
    Geographical range
    Native range: Africa, Asia, and Europe (USDA-GRIN, 2003)
    Known introduced range: North America (USDA-NRCS, 2002)
    Introduction pathways to new locations
    For ornamental purposes: Proulx (2000), states that, "B. umbellatus was likely brought to North America from Europe as a garden plant."
    Ship ballast water:
    Taken to botanical garden/zoo:


    Local dispersal methods
    Boat: Proulx (2000), states that, "Boaters can transport B. umbellatus on their equipment."
    Consumption/excretion: Proulx (2000), states that, "Muskrats may use parts of the plant to build houses and probably contribute to its local spread."
    For ornamental purposes (local): Proulx (2000), states that, "B. umbellatus was likely brought to North America from Europe as a garden plant."
    Garden escape/garden waste: Proulx (2000), states that, "B. umbellatus is probably spread over long distances by people who plant it in gardens."
    Other (local): Proulx (2000), states that, "Once in a watershed it spreads locally by rhizomes and root pieces that break off and form new plants."
    Water currents: Proulx (2000), states that, "Water and ice movements can easily carry B. umbellatus to new areas of a water body."
    Management information
    Mechanical: Proulx (2000), states that, "Cutting flowering rush below the water surface is an effective method of control. Cutting will not kill the plant but it will decrease the abundance. Multiple cuts may be required throughout the summer as flowering rush grows back from the root. All cut plant parts must be removed from the water. Hand digging can be used to remove isolated plants that are located downstream of larger infestations. Extreme care must be taken to remove all root fragments. Any disturbance to the root system will cause small reproductive structures on the roots to break off and spread to other areas of the waterbody. Therefore, methods such as raking or pulling which disturb the root system, but do not remove it, are not recommended control strategies.

    Chemical: It is very difficult to kill flowering rush with herbicides. Herbicides easily wash away from the narrow leaves of this plant. Herbicides are more effective on dry banks or in very shallow water. There is no herbicide that is selective for flowering rush and care must be taken to avoid damage to valuable wetland plants such as cattails."

    Nutrition
    Flowering rush grows well in light (sandy), medium (loamy) and heavy (clay) soils. The plant prefers acid, neutral and basic (alkaline) soils. It cannot grow in the shade. It requires wet soil and can grow in water (Plants for a Future, UNDATED).
    Reproduction
    Proulx (2000), states that, "B. umbellatus is probably spread over long distances by people who plant it in gardens. Once in a watershed it spreads locally by rhizomes and root pieces that break off and form new plants. Muskrats may use parts of the plant to build houses and probably contribute to its local spread. Boaters can transport B. umbellatus on their equipment. Water and ice movements can easily carry B. umbellatus to new areas of a water body." Proulx (2000) adds that, "Once in a watershed it spreads locally by rhizomes and root pieces that break off and form new plants." Delisle et al. (2003) states that, "B. umbellatus required less than 17 years (1905-22) to establish scattered colonies between Montréal and Québec City. Seeds may disperse over longer distances than vegetative fragments; this characteristics may further increase the rate at which this species spreads." The authors add that, "The warmer temperatures of newly exposed soils promote sprouting of B. umbellatus, which leads to multiplication of shoots and establishment of new individuals from rhizome fragments."
    Lifecycle stages
    Flowering rush is in flower from July to September, and the seeds ripen from August to September (in North America). The scented flowers are hermaphrodite and are pollinated by bees, flies and Lepidoptera (Plants for a Future, UNDATED).
    Reviewed by: Dr. Claude Lavoie, Ecole superieure d'amenagement du territoire et developpement régional (ESAD) Universite Laval. Quebec, Canada
    Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
    Last Modified: Friday, 8 July 2005


ISSG Landcare Research NBII IUCN University of Auckland