water horsetail

(Equisetum fluviatile)

               
Conservation Status

IUCN Red List

LC - Least Concern

water horsetail

NatureServe

NNR - Unranked

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

OBL - Obligate wetland

Midwest

OBL - Obligate wetland

Northcentral & Northeast

OBL - Obligate wetland

Nativity

Native

Occurrence

 

Habitat

Moist. Marshes, shallows, springs, water less than 40 deep.

Sporulation

June to August

     
Height

14 to 40

     

Identification

This is an erect, semi-aquatic, emergent aquatic perennial that rises from widely creeping rhizomes. It often forms dense colonies.

The stems are erect, 14 to 40 tall, 1 16 to 5 16 in diameter, hollow, stiff, and green to dark green. The central cavity is 8 10 to 9 10 the diameter of the stem. The stems have 15 to 25 fine, vertical ridges. The ridges are smooth to the touch but do not have silica deposits. They are annual, lasting just one year. 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 green to brownish-green, with a black band at the tip only. They are to long. At the tip of the sheath are 12 to 24 free lobes appearing as tiny, dark brown or black teeth. The teeth are narrow, 1 16 to 3 32 long, and occasionally have a white border. The teeth are not jointed and usually persist. As they age the sheath and teeth become ash gray, and the sheath often develops a narrow black band at the base.

A whorl of slender branchlets is sometimes produced at the middle nodes. The branchlets are 4- or 6-angled, solid, ascending or sometimes horizontal, never drooping, and usually do not themselves branch. Like the stems, the branchlets have segments with sheaths. The first segment of each branchlet is shorter than the sheath (from the branch to the tip of the teeth) below the node from which it extends. The branchlet sheath has 4 to 6 narrow teeth along the top rim, the number of teeth equaling the number of branchlet ridges.

Spore cones appear in June to August at the end of the main stem or occasionally on upper branches. They are attached to the stem on a long stalk. They are yellowish-green, blunt, and to ¾ long. They wither away after shedding their pollen.

 
Similar
Species

Marsh horsetail (Equisetum palustre) stems are rough to the touch and have 4 to 8 vertical ridges. The hollow in the stem center is less than the diameter of the stem. The cone is longer, ¾ to 1½ long.


Distribution Distribution Map   Sources: 2, 3, 4, 5, 7, 28.

Comments

Taxonomy
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 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.

The genus Equisetum is divided into two subgenera, Equisetum and Hippochaete. water 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.

In this subgenus, the stems tend to be regularly branched, the branches appearing in a whorl at each stem node. This gives the plant the appearance of a horse’s tail, giving rise to the common name “horsetail”. The aerial stems of most of the species in this subgenus are annual.


Taxonomy

No Rank:

Moniliformopses (Equisetum + ferns)

 

Class:

Equisetopsida (horsetails)

 

Order:

Equisetales (horsetails)

 

Family:

Equisetaceae (horsetails)

 

Genus:

Equisetum

 

Subgenus:

Equisetum (horsetails)

 
Synonyms

Equisetum fluviatile var. limosum

Equisetum limosum

 
Common
Names

pipes

river horsetail

swamp horsetail

water horsetail


 

 

 

 

 

 

 

 

 

Glossary

node

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

 

rhizome

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

       

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  Water Horsetail
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Published on Feb 12, 2014

A guide to the diagnostic features of Equisetum fluviatile (Water Horsetail) to aid in the identification of the species.

 
     

 

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  Water Horsetail: Natures Steel Wool
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Published on Jan 31, 2013

The water horsetail (Equisetum fluviatile), also known as the Swamp Horsetail, is a perennial horsetail that commonly grows in dense colonies along freshwater shorelines or in shallow water, growing in ponds, swamps, ditches, and other sluggish or still waters with mud bottoms.

The Water Horsetail ranges throughout the temperate Northern Hemisphere, from Eurasia south to central Spain, northern Italy, the Caucasus, China, Korea and Japan, and in North America from the Aleutian Islands to Newfoundland, south to Oregon, Idaho, northwest Montana, northeast Wyoming, West Virginia and Virginia.

The Water Horsetail has historically been used by both Europeans and Native Americans for scouring, sanding, and filing because of the high silica content in the stems. Early spring shoots were eaten. Medically it was used by the ancient Greeks and Romans to stop bleeding and treat kidney ailments, ulcers, and tuberculosis, and by the ancient Chinese to treat superficial visual obstructions. Rootstocks and stems are sometimes eaten by waterfowl. Horsetails absorb heavy metals from the soil, and are often used in bioassays for metals.

Source: http://en.wikipedia.org/wiki/Equisetum_fluviatile

 
     
  Equisetum fluviatile
wander van laar
 
   
 
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Published on May 18, 2014

 
     

 

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