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Common Name: Giant Horsetail

General Information

Equisetum telmateia is a perennial plant that can grow up to 2.00 metres tall.
It is harvested from the wild for local use as a food, medicine and source of materials.

Known Hazards

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 - see the notes on medicinal uses for more information[].

Botanical References

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Range

Europe, including Britain, from Sweden south and east to N. Africa and W. Asia, N.W. N. America.

Habitat

Damp shady banks etc, to 350 metres[].

Properties

Edibility Rating
Medicinal Rating
Habit	Perennial
Height	2.00 m
Cultivation Status	Wild

Cultivation Details

Prefers a moist soil with a pH between 6.5 and 7.5[].
Plants are hardy to about -30°c[].
Plants have a deep and penetrating root system and can be invasive. If grown in the garden they are best kept in bounds by planting them in a large container which can be sunk into the ground[].

Edible Uses

Strobil (the fertile shoots in spring) - raw or cooked[]. The tough outer fibres are peeled off, or can be chewed and then discarded[].
The vegetative shoots, produced from late spring onwards, were occasionally cleaned of their leaves, sheathing and branches and then eaten by native North American Indians, but only when very young and tightly compacted[].
Root - cooked[].

Medicinal

The plant is astringent and diuretic[]. A decoction has been used to treat 'stoppage of urine'[]. A poultice of the rough leaves and stems is applied to cuts and sores[].

Other Uses

The stems are very rich in silica[]. They are used for scouring and polishing metal[, , , , , ] and as a 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 good liquid feed[]. Used as a hair rinse it can eliminate fleas, lice and mites[].
The black roots have been used for imbrication on coiled baskets[].

Propagation

Spores - best collected as soon as they are ripe in the spring and surface-sown immediately on a sterile compost. Keep moist and pot up as soon as the plants are large enough to handle. Very difficult[].
Division. The plants usually spread very freely when well sited and should not really need any assistance.