Butomus umbellatus (Flowering Rush)

Plant Info
Also known as:
Genus:Butomus
Family:Butomaceae (Flowering Rush)
Life cycle:perennial
Origin:Europe, Asia
Status:
  • Early Detection weed, Ramsey County
  • Invasive - ERADICATE!
  • Prohibited or Restricted species
Habitat:sun; water to 6-ft depth; marshes, ponds, lakes, rivers, mudflats
Bloom season:June - August
Plant height:3 to 4 feet
Wetland Indicator Status:GP: OBL MW: OBL NCNE: OBL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 3-petals Cluster type: flat

[photo of flowers] Convex cluster (umbel) of ¾ to 1¼-inch flowers on stalks 2 to 4 inches long. Flowers have 3 pink, oval to egg-shaped petals alternating with 3 shorter pink to greenish, more lance shaped sepals. The 9 stamens are deep pink to red until they mature and release the yellow/orange pollen. In the center is a whorl of 6 styles fused at the base. Several papery bracts surround the base of the cluster. The cluster is at the tip of a long, sturdy stem with buds developing and opening throughout the season creating a mix of maturing seed capsules, open flowers and small embryonic flower buds present at the same time.

Leaves and stems: Leaf attachment: basal Leaf type: simple

[photo of twisted leaves] Leaves are basal, submersed in deeper water and emergent in shallower water. Emergent leaves are generally ½ to 2/3 the height of the flowering stem, the blades slender, may be twisted to some degree, erect and grass-like to the casual observer but the blade is conspicuously ribbed along the mid-vein on the underside and triangular in cross section. Both stalk and blades are glossy surfaced.

[photo of submersed leaves] In deeper water leaves are completely submerged, flowing freely, ribbon-like. Submersed plants in deeper water do not flower but spread effectively by rhizomes.

Fruit: Fruit type: capsule/pod

[photo of fruit] Fruit is brownish-maroon with 6 teardrop shaped sections enclosed at the base by the dried petals and sepals.

Notes:

Flowering Rush is a native of Eurasia first found in North America along the St. Lawrence Seaway over a century ago. Since then it has spread through the Great Lakes and inland all the way to the Pacific coast and was first reported in Minnesota in Anoka County in 1968. A serious wetland invasive species, it chokes out shoreline species both in and out of the water. When not flowering it is difficult to identify, as it closely resembles a number of native wetland species, such as common bullrush, but of special note is the twisting of emergent leaves. This trait was observed in a local population but not mentioned in any references so was considered an anomaly until I came upon the species description at Finland's Naturegate web site, at the bottom of the page.

Flowering Rush spreads primarily by rhizomes, but also by tubers transported by wildlife, bulblets formed in the flower clusters transported by water and wildlife, and occasionally from seed (most seed produced in MN populations is not viable). However, it is the unethical sale and distribution of it by the gardening industry that greatly multiplies the risk of spread. While unlawful to posses or distribute in the State of Minnesota, there is little or no oversight of internet sales and too few customers take the time to inform themselves of the environmental hazards of non-native species. The Minnesota DNR tracks all reports of this pest and some efforts are taken to reduce its impact but there is no statewide control program at this time. Once established there are few effective measures for its suppression or eradication. Mechanical and manual harvesting and herbicide treatments can reduce its numbers but so far has not been able to wipe it out. It is so bad in Detroit Lakes that it must be dredged periodically (no small expense) to keep the public beach open and accessible.

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More photos

Photos by Peter M. Dziuk taken at a small residential pond in Lino Lakes, Anoka County. Other photos courtesy the Minnesota Department of Natural Resources.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Elizabeth - Faribault, MN
on: 2013-05-12 13:52:31

This species is found on the west edge of Cannon Lake, at the Warsaw Bridge on the south bank.

Posted by: carole - Flwrg rush is confirmed in Bald Eagle Lk White Bear Twnsp
on: 2013-12-10 13:50:05

It has been reported on EDDMapS; confirmed by MNDNR. I can't say that it isn't in Ramsey County anymore :(

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