Horsetail fern Equisetum arvense is a primitive plant belonging to the only surviving genus of a group that dominated parts of the Earth’s vegetation during the Cretaceous period. It can be a tiresome weed in gardens because its creeping underground stems can be hard to eliminate.

Its medicinal value is largely attributed to its high silica content, though it also contains alkaloids, saponins, flavonoids and nicotine. Silica preserves the elasticity of connective tissue and controls the absorption of calcium. It is thus necessary for maintaining healthy skin, hair, nails, teeth and bones.

Although not well researched, horsetail is used to treat a wide variety of medical conditions, including cystitis, prostatic enlargement, bedwetting in children, atheroma (fatty deposits in the arteries), chronic lung conditions, rheumatoid arthritis and period pains. For the last two conditions, treatment may take the form of a silica bath: simmer 200g of the dried herb in 5 litres of boiling water for five minutes. Strain, and then add to the bath water.

One non-medicinal use for all the Equisetae was as pan scourers before the days of steel wool, the high silica content conferring a suitably abrasive property to the plants.

Caroline Wheeler