Description:
Perennial growing to 0.6m.
Horsetail is a unique plant with two distinctive types of stems. One variety of stem grows early in spring and looks like asparagus, except for its brown color and the spore-containing cones on top. The mature form of the herb, appearing in summer, has branched, thin, green, sterile stems and looks very much like a feathery tail.  Horsetail is the sole descendant of the giant fernlike plants that covered the earth some 200 million years ago. The herb's creeping rhizome sends up hollow, jointed, virtually leafless, bamboo-like stalks that reach 6 feet. At the ends of the stacks, spore-bearing structures develop which resemble horsetails, corncobs, or bottle brushes.

Distribution and habitat:
Meadow; Hedgerow.
Horsetail is widely distributed throughout the temperate climate zones of the northern hemi-sphere, including Asia, North America, and Europe. 

Hystory:
The name horsetail, often used for the entire group, arose because the branched species somewhat resemble a horse's tail, the name Equisetum being from the Latin equus, "horse", and seta, "bristle". Other names include candock (applied to branching species only), and scouring-rush (applied to the unbranched or sparsely branched species). The latter name refers to the plants' rush-like appearance; the stems were used for scouring cooking pots in the past (due to them being coated with abrasive silica).

Parts used:
Stems, leaves (grass)

Constituens:
Horsetail is very rich in silicic acid and silicates, which provide approximately 2-3% elemental silicon. Potassium, aluminum, and manganese along with fifteen different types of bioflavonoids are also found in the herb. The presence of these bioflavonoids are believed to cause the diuretic action, while the silicon content is said to exert a connective tissue-strengthening and anti-arthritic action. 
Some experts have suggested that the element silicon is a vital component for bone and cartilage formations This would indicate that horsetail may be beneficial in preventing osteoporosis. 
Anecdotal reports suggest that horsetail may be of some use in the treatment of brittle nails. 
The constituents are: 
Alkaloids, including nicotine, palustrine and palustrinine.
Flavonoids such as isoquercitrin and equicetrin.
Sterols including cholesterol, isofucosterol, campesterol. 
Silicic acid. 
Misc: a saponin equisitonin, dimethylsulphone, thiaminase & aconitic acid. 

Edible Uses:
Edible Parts: Root; Stem.
Strobil (the fertile shoots in spring) - cooked and used as an asparagus substitute. They should be used when young but even so it is probably best to change the water, perhaps 3 - 4 times. One report says that they can be eaten raw, they are peeled and the shoot tip is discarded. It is said to be a very tedious operation and they should not be eaten raw in any quantity, see the notes above on toxicity. Some native tribes liked to eat the young vegetative shoots, picked before they had branched out, and would often collect them in great quantity then hold a feast to eat them. The leaf sheaths were peeled off and the stems eaten raw - they were said to be 'nothing but juice. Roots - raw. The tuberous growths on the rhizomes are used in the spring. The black nodules attached to the roots are edible. It takes considerable effort to collect these nodules so it is normally only done in times of desperation. However, native peoples would sometimes raid the underground caches of roots collected by lemmings and other rodents in order to obtain these nodules. A further report says that the peeled stems, base of the plant, root and tubers were eaten raw by the N. American Indians, the report went on to say that this may be inadvisable.

Medicinal Uses:
Anodyne; Antiseptic; Astringent; Cardiac; Carminative; Diaphoretic; Diuretic; Galactogogue; Haemostatic; Homeopathy; Nervine; Vulnerary.
Horsetails have an unusual chemistry compared to most other plants. They are rich in silica, contain several alkaloids (including nicotine) and various minerals. Horsetail is very astringent and makes an excellent clotting agent, staunching wounds, stopping nosebleeds and reducing the coughing up of blood. It helps speed the repair of damaged connective tissue, improving its strength and elasticity. The plant is anodyne, antihaemorrhagic, antiseptic, astringent, carminative, diaphoretic, diuretic, galactogogue, haemostatic and vulnerary. The green infertile stems are used, they are most active when fresh but can also be harvested in late summer and dried for later use. Sometimes the ashes of the plant are used The plant is a useful diuretic when taken internally and is used in the treatment of kidney and bladder problems, cystitis, urethritis, prostate disease and internal bleeding, proving especially useful when there is bleeding in the urinary tract. A decoction applied externally will stop the bleeding of wounds and promote healing. It is especially effective on nose bleeds. A decoction of the herb added to a bath benefits slow-healing sprains and fractures, as well as certain irritable skin conditions such as eczema. The plant contains equisetic acid, which is thought to be identical to aconitic acid. This substance is a potent heart and nerve sedative that is a dangerous poison when taken in high doses. This plant contains irritant substances and should only be used for short periods of time. It is also best only used under the supervision of a qualified practitioner. A homeopathic remedy is made from the fresh plant. It is used in the treatment of cystitis and other complaints of the urinary system.

Others Uses:
Dye; Fungicide; Liquid feed; Musical; Paper; Polish; Sandpaper; Scourer.
The stems contain 10% silica and are used for scouring metal and as a fine sandpaper. They can also be used as a polish for brass, hardwood etc. The infused stem is an effective fungicide against mildew, mint rust and blackspot on roses. It also makes a good liquid feed. A light pink dye is obtained from the stem. It is yellow-gray according to another report. The plant has been used for making whistles.

Dosage:
Horsetail can be taken daily as a tea at 1-4 grams per day.
Infusion: pour a cup of boiling water onto 2 teaspoonfuls of the dried plant and let infuse for l5-20minutes.. This should be drunk three times a day.
Bath: A useful bath can be made to help in rheumatic pain and chilblains. Allow l00 grams (3 l/2 ounces of the herb to steep in hot water for an hour. Add this to the bath.
Tincture: take 2-6 ml of the tincture three times a day.

Safety:
This herb should not be used by pregnant women, those who are weak, or those with excessive dryness or frequent urination.
Horsetail is generally considered safe for non-pregnant adults at the recommended dose. The only concern would be that the correct species of horse-tail is used; Equisetum palustre is another species of horsetail, which contains toxic alkaloids and is a well-known livestock poison. FDA rates horsetail as a herb of undefined safety.
The Canadian Health Protection Branch requires supplement manufacturers to document that their products do not contain the enzyme thiaminase, found in crude horsetail, which destroys the B vitamin thiamin. Since alcohol, temperature, and alkalinity neutralize this potentially harmful enzyme, tinctures, fluid extracts, or preparations of the herb subjected to 100 degreeC temperatures during manufacturing should be the preferable form of the plant utilized for medicinal use.
Horsetail is relatively high in selenium. Too much selenium may cause birth defects. In marshes downstream from heavily fertilized agricultural areas, horsetail may be hazardously high in selenium. Pregnant women should avoid this herb. Equisetine, a chemical contained in horsetail, in large amounts is a nerve poison. Don't let children play with the stems. Ingesting the juice has reportedly caused reactions in children.