Photo source: Julie Boudreau

Case Studies - Flowering Rush - Butomus umbellatus

Flowering rush (Butomus umbellatus) is a hardy perennial aquatic plant that originates from Eurasia and is most frequently found on shores of riverbanks, ponds and lakes. Since it's introduction to North America in the late 1800's, it has become a very popular ornamental water garden plant. Given its hardiness and ability to adapt to a wide temperature range, flowering rush can today be found in every region of the country. Its widespread occurrence is likely the result of extensive ornamental garden planting.

This rush-like plant can grow either submerged in the water or above it. It spreads mainly by rhizomes and root pieces (small tubers) that can break off, be displaced by currents, animals such as muskrats or recreational watercraft, and form new plants. Flowering rush is considered to be aggressive and once it colonizes, it develops a thick root system that can displace native shore vegetation and obstruct recreational boat traffic.

Because, once established, it can persist indefinitely, and because it grows back from the roots, cutting the plant below the surface of the water has been shown to be an effective means of control. Although this does not eliminate the plant, it diminishes its abundance. Care must be taken to not disturb the root system and to remove all root fragments to prevent root pieces from spreading to other areas and forming new plants. As with many other invasive aquatic plants, prevention of accidental release remains the best means of controlling its spread.

For more detailed information on this invasive aquatic plant, contact:

Global Invasive Species Database; www.issg.org/database.

Ontario Federation of Anglers and Hunters; www.invadingspecies.com