P1246990954KepDm

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Introduction Salish Kootenai College, the
University of Montana, and Montana State
University are studying the distribution,
ecological impacts, and control strategies of the
invasive plant, flowering rush (Butomus
umbellatus). The current study area is the
Flathead Lake and river system in northwest
Montana, where documented infestations extend at
least seventy miles downstream. Infestations are
found along lakeshore bay areas from shoreline to
20 ft. of water depth, docks and marinas,
backwaters, and irrigation delivery systems. In
an expanding effort, we are surveying Columbia
River system managers, state and university
herbariums, Tribes, and interested entities on
any infestations. We are asking your help to
identify these locations of this invasive aquatic
plant. Please help by participating in the
following survey. Thank you.
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Exotic Flowering Rush Flowering Rush (Butomus
umbellatus) is an exotic aquatic plant that has
been introduced into the Flathead Lake water
system - a major tributary of the Columbia River
System. It can grow above and below the water
surface in shallow or moderate depths. This
plant has shown to invade shallow water in lakes
and wetlands, forming dense stands that
interferes with recreational lake use with
unknown impacts on fish and wildlife. It also
impedes flow in irrigation delivery systems.
Identification This aquatic plant is easiest to
identify when in flower, which seems to occur in
only 2 of any infestation (see photo).
Flowering rush have green leaf stems that are
uniquely triangular shaped (see photo), flower
stems which are round, and leaf tips which may be
spirally twisted, . The leaves are erect and
grow up to 8 feet in height depending on water
depth. Above water, the leaves appear to be
rigid, while under water are limp. Flowering
rush forms an extensive root system and
reproduces by rhizomes and bulblets that are
released when disturbed.
Stems have triangular cross section
Umbrella shaped clusters with each flower having
3 whitish pink petals.
Management/Prevention Cutting flowering rush does
not kill the plant and it is highly recommended
that all plant parts be removed from the water
when disturbed. Flowering rush is banned and
quarantined by several states.