A perennial growing to 1 m (3ft 3in) with creeping, branching rootstocks, rooted at the nodes. Upright, aerial, green stems are cylindrical, simple or with whorled branches at the jointed nodes. The surfaces of the stems are covered with silica. It flowers in early spring, producing terminal cones and seeds ripen from July to August. It likes a sunny or semi-shaded position in moist soil.

used by the Iroquois as a diuretic – decoction of plant taken for urinating too infrequently. Infusion of whole plant used as an eye-wash for white spot on the eye. Decoctions of the plant have been taken for kidney trouble and backache. Compound decoction of roots taken for gonorrhoea.

Medicinal uses Uses supported by clinical data An open clinical trial has indicated a possible diuretic effect (40). Uses described in pharmacopoeias and well-established documents Used internally for kidney and bladder diseases, oedema and as an adjuvant in slimming diets (41). It is applied as irrigation therapy for infectious and infl ammatory diseases of the genitourinary tract, and kidney stones (12, 23, 42). Used externally as supportive treatment for slowhealing wounds (43). Uses described in traditional medicine Symptomatic treatment of chronic swelling of the legs, slow-healing sprains and fractures, irritable skin conditions, gout, rheumatism, arthritis, hepatitis, fractures, sore throat, dermatological problems and haemorrhoids (44–47). In folk medicine Herba Equiseti is used as an analgesic, antihypertensive, clotting agent, haemostatic, depurative, astringent, diuretic and anti-infl ammatory (48–50). In Indian Ayurvedic medicine it is used for the treatment of infl ammation or benign enlargement of the prostate gland, for urinary incontinence and for enuresis in children (51). Contraindications No irrigation therapy (hydrocolon therapy) is recommended in patients with oedema due to impaired heart and kidney function (40). If signs of hypersensitivity reactions appear, Herba Equiseti must not be used again.

HISTORICAL ** "Gauda [a typo for Cauda] equine. Horsetail; is of a drying binding quality, cures wounds, and is an admirable remedy for sinews that are shrunk; yea, Galen saith that it cures sinews though they be cut in sunder; but Columbus holds that is incurable unless they be cut within the muscle; well then, take Galen in the charitable sense. ... it is a sure remedy for bleeding at the nose, or by wound, stops the terms in women, Fluxes, Ulcers in the Reins [kidneys] or Bladder, coughs, ulcers, in the lungues, Difficulty of breathing."

Previously grown as Equisetum hyemale var. affine

Otherwise known as the “Scouring or Dutch Rush”, Professor Dayan contributes that “…the high silica content of the stems has led to their use for scouring pots and pans and polishing metal. It was once imported from the Netherlands to Britain.”

In Japan, the stems have been used as fine sandpaper. The stems are first bleached by repeated wetting and drying in the sun. They can also be used as a polish for wooden floors and furniture. The infused stem is an effective fungicide against mildew, mint rust and blackspot on roses. It also makes a liquid feed. Used as a hair rinse it can eliminate fleas, lice and mites. A light pink dye is obtained from the stem. The hollow stems have been used as whistles. Another report says that the stem joints are pulled apart and used by children to produce a whistling sound.

The Karok have use the dried stalks to sharpen mussel shell scrapes and for polishing arrows.

Horsetails have an unusual chemistry compared to most other plants. They are rich in silica, contain several alkaloids (including nicotine). Caution is advised (see notes under toxicity). The peeled stems, base of the plant, root and tubers were eaten raw by the N. American Indians. The young shoots were cooked in spring and the roots dried and then cooked. It was a source of starch. Due to the high silica content eating it now is considered inadvisable.

Large quantities of the plant can be toxic. This is because it contains the enzyme thiaminase, a substance that can rob the body of the vitamin B complex. In small quantities this enzyme will do no harm to people eating an adequate diet that is rich in vitamin B, though large quantities can cause severe health problems. The enzyme is destroyed by heat or thorough drying, so cooking the plant will remove the thiaminase. The plant also contains equisetic acid.

Toxic due to thiaminase content and high concentration of silica crystals.