Equisetum arvense

The Field Horsetail (Equisetum arvense) is a rather bushy perennial with a rhizomatous stem formation native to the northern hemisphere. These horsetails may have sterile or fertile stems. Sterile stems start to grow after the fertile stems have wilted. The sterile stems tend to be much taller and bushier, with the jointed segments being around one inch long with a diameter of about 1/20th of an inch. These segments contain one set of whorled, slender, erect branches each. Some stems can have as many as 20 segments and be as tall as 2-24 inches. The fertile stems tend to be half as tall as the sterile stems and also tend to be more succulent.

This plant also has a very high diploid number - 216 (108 pairs of chromosomes) - which is roughly 5 times bigger then human diploid number (46).

Uses
The plant contains several chemicals which can be used medicinally. It is rich in the minerals silicon (10%), potassium, and calcium, which gives it diuretic properties. It is prescribed to care for conjunctive tissues (cartilage, tendons, and bones) and also polyps, epistasis, and bleeding. The buds are eaten as a vegetable in Japan in spring time.

It was also once used to polish pewter and wood (gaining the name pewterwort) and to strengthen fingernails.

In herbalism it used to treat kidney and bladder problems, gastro-enteritis, and prostate and urinary infections. Externally it is used for chilblains and wounds.