The sandpapery stems of scouring rushes were once used to scour kitchen and other utensils. The Germans call the plant Zinnkraut, or “tin herb.” The plants’ coarse texture comes from silicates that accumulate on the exterior. Equisetums are used by musicians to clean and maintain reeds for woodwind instruments (it’s sold as “Dutch rush” or “reed rush”), and in Japan for giving a final polish to fine woodwork.
The mathematician John Napier, a Scotsman who lived in the late 1500s and early 1600s, is said to have invented logarithms after pondering the ever-decreasing spaces between the nodes toward the tips of equisetums. Logarithms are useful for calculating the half-life decay of radioactive substances, bacterial growth, population growth, compound interest, and much more. The pH, Decibel, and Richter scales are based on logarithms.
Equisetum has been used in several cultures as a folk remedy, but scientific evidence of its effectiveness is lacking. Certain species have also been eaten in Japan and by Native Americans in the Pacific Northwest, but consuming equisetum is not recommended.
Some horsetails and ferns contain an enzyme called thiaminase, which metabolizes (breaks down) thiamine (a B vitamin) and makes it unavailable for the body to absorb. Too much thiaminase can cause people to have thiamine deficiency, which can ultimately cause liver damage.
Although some property owners may try to grow A. hyemale as a water-loving plant that looks interesting in wintertime, this species spreads aggressively by its rhizomes. Once established, it can be difficult to eradicate: its rhizomes spread widely and deep, and even a tiny section of rhizome can become a new plant. Also, it’s resistant to herbicides. Considering its aggressiveness, for landscape use, we recommend only planting it in low, wet places where nothing else will grow. Otherwise, we suggest limiting it to containers.