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Equisetum arvense

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Equisetum arvense, the field horsetail or common horsetail, is an herbaceous perennial plant in the Equisetopsida (the horsetails), native throughout the arctic and temperate regions of the northern hemisphere. It has separate sterile non-reproductive and fertile spore-bearing stems growing from a perennial underground rhizomatous stem system. The fertile stems are produced in early spring and are non-photosynthetic, while the green sterile stems start to grow after the fertile stems have wilted and persist through the summer until the first autumn frosts.<ref name=hwh>Hyde, H. A., Wade, A. E., & Harrison, S. G. (1978). Welsh Ferns. National Museum of Wales Template:ISBN.</ref><ref name=fna>Flora of North America: Equisetum arvense</ref> It is sometimes confused with mare's tail, Hippuris vulgaris.<ref>Template:Cite journal</ref>

Etymology

The specific epithet arvense is from the Latin "arvum", meaning "ploughed", referencing the growth of the plant in arable soil or disturbed areas. The common name "common horsetail" references the appearance of the plant that when bunched together appears similar to a horse's tail.<ref name=Nox>Template:Cite book</ref>

Description

Equisetum arvense creeps extensively with its slender and felted rhizomes that freely fork and bear tubers. The erect or prostrate sterile stems are Template:Convert tall and Template:Convert diameter, with jointed segments around Template:Convert long with whorls of side shoots at the segment joints; the side shoots have a diameter of about Template:Convert. Some stems can have as many as 20 segments. The solid and simple branches are ascending or spreading, with sheaths that bear attenuate teeth. The off-white fertile stems are of a succulent texture, Template:Convert tall and Template:Convert diameter, with 4–8 whorls of brown scale leaves and an apical brown spore cone. The cone is Template:Convert long and Template:Convert broad.<ref name=hwh/> The fertile stems are typically precocious and appear in early spring.<ref name=Manual>Template:Cite book</ref> It is little changed from its ancestors of the Carboniferous period.

The plant is difficult to control due to its extensive rhizomes and deeply burrowing tubers. Fire, mowing, or slashing is ineffective at removing the plant as new stems quickly grow from the rhizomes. Some herbicides remove aerial growth but regrowth quickly occurs albeit with a reduction in frond density.<ref name=Nox/>

E. arvense is a nonflowering plant, multiplying through spores. It absorbs silicon from the soil, which is rare among herbs. It has a very high diploid number of 216 (108 pairs of chromosomes).<ref name="hwh" />

Habitat and distribution

Equisetum arvense grows in a wide range of conditions, in temperatures less than Template:Convert to greater than Template:Convert and in areas that receive annual rainfall as low as Template:Convert and as great as Template:Convert. It commonly occurs in damp and open woodlands, pastures, arable lands, roadsides, disturbed areas, and near the edge of streams. It prefers neutral or slightly basic clay loams that are sandy or silty, especially where the water table is high, though it can occur occasionally on slightly acid soils.<ref name=Nox/>

The plant is widespread in the northern hemisphere, growing as far as 83° North in North America and 71° North in Norway, Sweden, Finland, and Russia and as far south as Texas, India, and Iran. It is less widespread in the southern hemisphere, but it occurs in Argentina, Brazil, Chile, Madagascar, Indonesia, Australia, and New Zealand.<ref name=Nox/>

Beneficial uses

Drawing of a fertile stem of E. arvense, 10 cm as drawn. At the top is the strobilus, which consists of the axis (inside) and 15–20 horizontal circles of about 20 sporangiophores. Lower on the stem are two sheaths of merged microphylls. The stem has many strong lengthwise ridges.
The plant contains several substances that can be used medicinally. It is rich in the minerals silicon (10%), potassium, calcium, manganese, magnesium and phosphorus, phytosterols, dietary fiber, vitamins A, E and C, tannins, alkaloids, saponins, flavonoids, glycosides and caffeic acid phenolic ester. The buds are eaten as a vegetable in Japan and Korea in spring. All other Equisetum species are toxic.
Fertile shoots, in late April.

In polluted conditionsTemplate:Citation needed, it may synthesize nicotine.<ref name="Nicotine content of Equisetum">Template:Cite web</ref> Externally it was traditionally used for chilblains and wounds.<ref>Howard, Michael. Traditional Folk Remedies (Century, 1987); p.159-160</ref> It was also once used to polish pewter and wood (gaining the name pewterwort) and to strengthen fingernails. It is also an abrasive. It was used by hurdy-gurdy players to dress the wheels of their instruments by removing resin build up.<ref>La Vielleuse Habile, Jean-Francois Bouin, 1761, page 19.</ref>

Equisetum is used in biodynamic farming (preparation BD 508) in particular to reduce the effects of excessive water around plants (such as fungal growth). The high silica content of the plant reduces the impact of moisture.<ref name="City Food Growers">Template:Cite web</ref>

E. arvense has been used in traditional Austrian herbal medicine internally as tea, or externally as baths or compresses, for treatment of disorders of the skin, locomotor system, kidneys and urinary tract, rheumatism and gout.

Harmful effects

Sterile stems

Equisetum arvense is toxic to stock, particularly horses.<ref>Template:Cite web</ref>

It was introduced into New Zealand in the 1920s and was first identified as an invasive species there by Ella Orr Campbell in 1949.<ref name="Horticulture 2003">Template:Cite journal</ref> It is listed on the National Pest Plant Accord, prohibiting its sale, spread and cultivation.<ref>Template:Cite book</ref>

References

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External links

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