Flowering rush
Native to: Africa, Asia, Eurasia
This plant does not occur in Florida. However it is present in the northern tier of states from Vermont to Idaho, and in most of the southern half of Canada (Kartesz, 1999). It was introduced from both Europe and Asia as an ornamental.
Family: Butomaceae
Habit: Aquatic, moderately tall, rush-like perennial.
Leaves: Emersed form has “grassy,” erect leaves. Leaves are lax and floating when in deep water.
Flowers: Pink flowers are borne in an umbel (umbrella-like) at the top of a single flower stalk; the flowers are usually held above the leaves of the plants.
Fruit/Seeds: Indehiscent, many-seeded capsule.
Distribution in Florida: Not present
Flowering rush displaces native vegetation and can impede boat traffic and recreation. It spreads from horticultural plantings and once established in natural areas fragments and rhizomes can be moved easily by boats and ballast.
Do not plant. Clean all boat equipment and dump any water before moving to another waterbody.
Pull and dig out from landscape settings.
Extensive removal via heavy equipment.
None known.
Foliar application of herbicides to control flowering rush is challenging; typically only a small part of the plant emerges above the water, so limited foliage is available for herbicide coverage and uptake, resulting in poor herbicide absorption and incomplete control. Several herbicides have been evaluated for foliar applications; of these, imazapyr has shown the greatest potential for control of above-water growth but successive years of treatment may be needed to reduce root and rhizome biomass. Diquat has been used for in-water treatments in midwestern and northwestern systems that are greater than one foot deep; one or two applications per summer control foliage and reduce root and rhizome biomass. Bare-ground treatments of imazapyr and imazamox applied during drawdowns are also effective, but two or more consecutive years of treatment may be needed to achieve 100 significant root and rhizome reductions. There is no product that selectively controls flowering rush without the potential to harm other plants, so care must be taken during herbicide application to avoid impacts to nontarget species.
