Equisetum fluviatile (Water Horsetail)

Plant Info
Also known as:
Genus:Equisetum
Family:Equisetaceae (Horsetail)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; bogs, swamps, lakes, streams, ditches; standing water up to 3 feet deep
Fruiting season:late spring, summer
Plant height:2 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

Leaves and stems: Leaf attachment: whorl

[photo of stem and branches] The sterile stem is green and usually has whorled branches that are spreading to ascending. The “leaves” are reduced to a sheath that surrounds the stem, with 12 to 24 narrow, black-brown teeth around the top that occasionally have a narrow band of white around the edge.

[photo of stem cavity] The stem is green, stout and hollow with a large central cavity. The first branch internode is shorter than the stem sheath.

Fruit: Fruit type: spores on stalk

[photo of spore cone] Fertile stems are like the sterile stems, but with a ½ to 1-inch, blunt-tipped cone at the tip of the stem. The cone matures in summer and falls off after spores are released.

Notes:

Water Horsetail can create very large, dense colonies, often in the quiet waters of lakes and ditches. There are 2 other Equisetum species that have spreading to ascending branches: Field Horsetail (Equisetum arvense) and Marsh Horsetail (E. palustre). Of these, only E. fluviatile has a stem with a large central cavity so it compresses easily when squeezed. When branches are absent, E. fluviatile resembles Tall Scouring Rush (E. hyemale) or Smooth Scouring Rush (E. laevigatum), both of which have sheath teeth that usually drop off and do not persist. E. fluviatile hybridizes with E. arvense and their offspring, Equisetum × litorale, may be expected where the parents are both present. The hybrid closely resembles E. palustre but the first branch internode is longer than the associated stem sheath, where on E. palustre it is shorter. When trying to determine if the first branch internode is longer or shorter than the stem sheath, it is important to look at the lowest branch on the stem as those higher up the stem may have different lengths.

Please visit our sponsors

  • Must have book: Pollinators of Native Plants

Where to buy native seed and plants ↓

Map of native plant purveyors in the upper midwest

  • Shop for native seeds and plants at PrairieMoon.com!
  • Shooting Star Native Seeds - Native Prairie Grass and Wildflower Seeds
  • Morning Sky Greenery - Native Prairie Plants
  • Minnesota Native Landscapes - Your Ecological Problem Solvers
  • Natural Shore Technologies - Using science to improve land and water

More photos

Photos by K. Chayka taken in Itasca and Ramsey counties. Photos courtesy Cindy Hoffmann taken at Edenbrook Conservation Area, Hennepin County. Other photos courtesy Peter M. Dziuk.

Comments

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

Post a comment

Note: All comments are moderated before posting to keep the riff-raff out. An email address is required, but will not be posted—it will only be used for information exchange between the 2 of us (if needed) and will never be given to a 3rd party without your express permission.

For info on subjects other than plant identification (gardening, invasive species control, edible plants, etc.), please check the links and invasive species pages for additional resources.



(required)




Note: Comments or information about plants outside of Minnesota and neighboring states may not be posted because Id like to keep the focus of this web site centered on Minnesota. Thanks for your understanding.