Swamp Horsetail, Water horsetail
Equisetum fluviatile
Family: Equisetaceae
What it is like
Equisetum species - horsetail family are Creeping, perenial, Branching rootstocks, rooted at the nodes. The Arial stems may be annual or Perennial, are cylindrical, fluted, simple or with whorled branches at the jointed nodes. The internodes are usually hollow. The Surfaces of the stems are covered with Silica. The Cones are terminal.
Equisetum fluviatile is a PERENNIAL growing to 1.2 m (4ft). See above for USDA hardiness. It is hardy to UK zone 2. The seeds ripen from June to July. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist or wet soil and can grow in water.
Height (m): 1.2
Where it is found
Shallow water in lakes, ponds and ditches.
Arctic and temperate regions of Europe, including Britain, N. America and Asia.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 2
Strobil (the fertile shoots in spring) - cooked. Used as an asparagus substitute, though it is neither palatable nor nutritious. Caution is advised, see the notes above on toxicity. Roots - cooked. The roots contain a nutritious starch. Caution is advised, see the notes above on toxicity.
Root: includes bulbs, corms, tubers, rhizomes etc.
Stem: this often intergrades into leaves.
Medicine
Rating: 2
Horsetails have an unusual chemistry compared to most other plants. They are rich in silica, contain several alkaloids (including nicotine) and various minerals. The plant is styptic. The barren stems are used, they are most active when fresh but can also be dried and sometimes the ashes of the plant are used. A decoction applied externally will stop the bleeding of wounds and promote healing.
Styptic: An astringent that stops bleeding by contracting the blood vessels.
Other
Rating: 2
Dynamic accumulator.
Dynamic accumulator: Plants that gather minerals or nutrients from the soil and store them in a more bioavailable form and in high concentration in their tissues. Used as fertilizer or to improve mulch.
How it is grown
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.
Propagating it: 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.
Best place to grow: Pond; Bog Garden;
Habit: Perennial
Hardiness: 0-0
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: Semi-shade, no shade
Moisture: Moist, wet, water
Things to keep in mind
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.
Its other names
Local names
Synonyms
E. heliocharis. E. limosum.