Horsetail has been called a “living fossil” — its relatives were abundant in forests more than 100 million years ago, and some of these ancient horsetails grew to 90 feet tall! Those towering species are now extinct, but the smaller descendants of this genus still grow in the wet areas of every continent except Antarctica. These herbaceous plants have hollow stems, scalelike leaves, and brownish cones borne at the ends of the stems.
The stems contain silica, which explains the plant’s common names “bottle brush” and “scouring rush.” The stems can be dried and tied in bundles, then used as an abrasive to scour pots, shine metal, or sand wood. The belief that horsetail can strengthen nails, hair, teeth, and connective tissue is unsupported, however; your body cannot use silica in this form.
Common Names: Bottle Brush, Horsetail, Scouring Rush
Description: Sharp-toothed leaf sheaths on jointed stalks topped with flower spikes; later, whorls of needle-like leaves appear on hollow, 18-inch stems
Hardiness: To Zone 2
Parts Used: Stems
Range/Habitat: Naturalized throughout most of the world; moist woods and roadsides
Horsetail contains flavone glycosides and a saponin, which are thought to account for its diuretic properties. Teas and extracts made from the dried stems are taken to treat bladder infections and kidney stones. Applied directly to a wound, the herb can help stop bleeding. Native Americans used Equisetum arvense to treat rashes, cuts, and sores; to promote urine flow; and to ease headaches, kidney troubles, and other problems. In China,Equisetum hyemale is used for various conditions, including fever and dysentery.
Horsetail gives a yellowish green color to wool mordanted with alum and a deeper green when an iron mordant is used. Although some cultures reportedly eat this plant, this probably isn’t a good idea; some species contain a compound that destroys thiamine (vitamin B1), a vitamin essential to all mammals. A thiamine deficiency can lead to the condition known as beriberi, which can result in severe sickness and even death.
How to grow it
Horsetail is rarely cultivated because once it’s established, it can be extremely difficult to eradicate. If you wish to enjoy this interesting plant at home, plant it in a container and keep it just below the surface of a pond or water garden. Horsetail thrives in humus-rich, moist soil with an acid to neutral pH and full sun to partial shade. Harvest the stems in fall, when the silica content is highest. Propagate by division.