smooth scouring rush

(Equisetum laevigatum)

Conservation Status
smooth scouring rush
  IUCN Red List

not listed


N5? - Secure

SNR - Unranked


not listed

Wetland Indicator Status
  Great Plains

FAC - Facultative


FACW - Facultative wetland

  Northcentral & Northeast

FACW - Facultative wetland


Smooth scouring rush is an erect, 12 to 36 tall, unbranched perennial that rises from rhizomes.

The stems are erect, to 5 16 in diameter, light green, and hollow. They are normally unbranched, but may develop one or a few branches after injury, or in the second year. They have 10 to 32, usually at least 16, fine, vertical ridges that are smooth to the touch. They are annual, lasting less than one year. The central cavity is to ¾ the diameter of the stem. The portion of the stem between the nodes is up to several inches near the bottom, becoming progressively shorter as they ascend the stem.

The leaves are reduced in size, fused together for most of their length, and appressed against the stem, forming a collar-like sheath around the nodes. The sheaths are a lighter shade of green than the stem, usually with a black band at the tip only, sometimes also the lowest ones with a black band at the base or black throughout. They are longer than wide, ¼ to long, to wide. At the tip of the sheath are 10 to 32, usually at least 16, free lobes appearing as tiny, black teeth. The teeth are jointed and fall off at the joint promptly at maturity, leaving just a dark rim on the sheath.

A solitary, spore-bearing cone is borne at the end of each fertile stem. The cone is to 1 long, circular in cross-section, and elliptic in long section, and rounded at the tip. It often ends with a tiny, inconspicuous, abrupt, flexible point at the tip (apiculate). Infertile stems are similar to fertile stems but lack the terminal cone. The cone falls off after releasing spores.




12 to 36


Similar Species


Scouring rush horsetail (Equisetum hymale ssp. affine) is a taller plant, usually reaching 24 to 48 tall. The stems are darker green, rough to the touch, and evergreen. The sheaths appear squarish, are tan, grayish, or white, and have a black band at both the base and the tip. The teeth on the sheath often persist after maturity. The cones are conspicuously apiculate.

Variegated scouring rush (Equisetum variegatum ssp. variegatum), is a shorter plant, only 4 to 18 tall. The stems are thinner, 1 32 to 3 32 in diameter. The sheaths are slightly flared outwards at the tip. There are 5 to 12 vertical ridges on the stem and the same number of teeth on the sheath. The teeth have conspicuous white margins. The teeth are not jointed and usually persist. The cone is shorter, long or less. It is found only in the upper third of the state.


Wet meadows, prairies.






Pests and Diseases




The stems are unbranched or have few irregular branches. They are coated with an abrasive silica, and were used for scrubbing cooking pots. This, along with their rush-like appearance, gave rise to the common name “scouring rush”.


Distribution Map



2, 3, 4, 5, 7, 28, 29, 30.









  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Polypodiophytina  
  Class Polypodiopsida (ferns)  
  Subclass Equisetidae (horsetails)  


Equisetales (horsetails)  


Equisetaceae (horsetail)  


Equisetum (horsetails)  
  Subgenus Hippochaete (scouring rushes)  

Monotypic genus, family, and order
There are 15 species of Equisetum, which is the only living genus in the family Equisetaceae, which is the only family in the order Equisetales, which is the only order in the class Equisetopsida.

The genus Equisetum is divided into two subgenera, Equisetum and Hippochaete. Field horsetail is one of the eight species in the subgenus Equisetum. Six of those eight species are found in North America. Five are found in Minnesota.

Living fossil
The history of Equisetum has been traced 300 million years to the Cretaceous period, and possibly to the Triassic period. That could make Equisetum the oldest living genus of vascular plants.


Subordinate Taxa






Equisetum funstoni

Equisetum funstonii

Equisetum kansanum

Equisetum laevigatum ssp. funstonii

Hippochaete laevigata


Common Names



smooth horsetail

smooth scouring rush

smooth scouring-rush

smooth scouringrush













Ending in a short, abrupt, flexible point.



The small swelling of the stem from which one or more leaves, branches, or buds originate.



A horizontal, usually underground stem. It serves as a reproductive structure, producing roots below and shoots above at the nodes.

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    smooth scouring rush   smooth scouring rush  
    smooth scouring rush      


    smooth scouring rush   smooth scouring rush  

Irregularly Branched Stem

    smooth scouring rush      


    smooth scouring rush   smooth scouring rush  






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Agassiz Dunes SNA (MN DNR)

Anna Gronseth Prairie

Blazing Star Prairie

Blue Mounds State Park

Boot Lake SNA

Buffalo River State Park

Butternut Valley Prairie SNA

Cedar Mountain SNA

Cedar Rock SNA

Chippewa Prairie

Compass Prairie SNA

Cottonwood River Prairie SNA

Crow-Hassan Park Reserve

Des Moines River SNA

Felton Prairie SNA, Bicentennial Unit

Felton Prairie SNA, Shrike Unit

Felton WMA

Foxhome Prairie

Frenchman’s Bluff SNA

Glacial Lakes State Park

Glendalough State Park

Greenleaf Lake SRA

Grey Cloud Dunes SNA

Hastings Sand Coulee SNA

Helen Allison Savanna SNA

Hole-in-the-Mountain Prairie

Holthe Prairie SNA

Hyland Lake Park Reserve

Hythecker Prairie SNA

Iron Horse Prairie SNA

Iron Springs Bog SNA

Jensen Memorial WMA

Joseph A. Tauer Prairie SNA

Kasota Prairie

Kellogg Weaver Dunes SNA, Kellogg Weaver Unit

Kellogg Weaver Dunes SNA, Weaver Dunes Unit

Kilen Woods State Park

Lake Alexander Woods SNA, South Unit

Langhei Prairie SNA

Leif Mountain

Lundblad Prairie SNA

Margherita Preserve-Audubon Prairie

McKnight Prairie

Miller Prairie, East Unit

Moose Lake State Park

Mound Spring Prairie SNA, North Unit

Mound Spring Prairie SNA, South Unit

Northern Tallgrass Prairie NWR, Hoffman Unit

Northern Tallgrass Prairie NWR, Pavia Unit

Northern Tallgrass Prairie NWR, Spieker Unit

Northern Tallgrass Prairie NWR, Touch the Sky Prairie Unit

Old Mill State Park

Oronoco Prairie SNA

P.N. and G.M. Nelson Wildlife Sanctuary

Pankratz Memorial Prairie, North Unit

Pembina Trail Preserve SNA, Crookston Prairie Unit

Pin Oak Prairie SNA

Plover Prairie, East Unit

Prairie Coteau SNA

Prairie Creek WMA, Koester Prairie Unit

Racine Prairie SNA

Regal Meadow

Rice Lake Savanna SNA

River Terrace Prairie SNA

Roscoe Prairie SNA

St. Croix Savanna SNA

Sandpiper Prairie SNA

Santee Prairie SNA

Savage Fen SNA

Schaefer Prairie

Sedan Brook Prairie SNA

Seven Sisters Prairie

Sheepberry Fen

Spring Creek Prairie SNA

Spring Prairie Preserve

Staffanson Prairie

Swedes Forest SNA

Town Hall Prairie

Tribute WMA

Twin Valley Prairie SNA

Two Rivers Aspen Prairie Parkland SNA

Tympanuchus Prairie

Verlyn Marth Memorial Prairie SNA

Vermillion River WMA

Wahpeton Prairie WMA

Whitetail Woods Regional Park

Wild Indigo SNA

Yellow Bank Hills SNA

Zimmerman Prairie







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