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Portrait of Marsh horsetail

Nature · Ferns, grasses & other plants

Marsh horsetail

Native · perennial spore plant 10–60 cm · marshes, wet meadows and fens

Equisetum palustre — Equisetaceae

Marsh horsetail is a slender, jointed, spore-bearing plant of wet meadows, marshes and fen edges, common throughout Britain. It belongs to the only surviving genus of a lineage that reaches back to the Carboniferous coal forests. It matters to farmers because it is among the most poisonous plants of wet grassland, containing alkaloids that can kill cattle and horses, particularly when grazed young or cut into hay.

How to spot them

  • ▸Slender, ridged green stems 10–60 cm tall, jointed into segments, each joint wrapped in a toothed sheath
  • ▸Branches, when present, have their tiny teeth pressed close to the stem (appressed) rather than spreading
  • ▸Grows in wet ground: marshes, wet meadows, ditch sides and fen edges
  • ▸A small cone at the tip of green stems, unlike field horsetail, whose cones sit on separate pale spring stems
  • ▸Look-alike: field horsetail; check the sheath teeth and the way the central hollow compares in size to the ring of small hollows around it, best with a hand lens

How to know it

A jointed, spore-bearing plant of wet meadows whose stems contain alkaloids that poison cattle and horses

Marsh horsetail — palustrine and related alkaloids.

Its species name means 'of the marsh', and its cone sits at the tip of an ordinary green stem

Marsh horsetail — palustris means 'of the marsh'.

A plant whose lineage includes the Carboniferous tree-sized calamites, though this British species is only knee-high

Marsh horsetail — genus Equisetum.

Is most toxic to grazing stock in its early growth stages and is dangerous when it contaminates hay

Marsh horsetail — alkaloid levels peak early in the season.

Genus name is from the Latin for 'horse bristle'; this member has teeth pressed flat against its branches

Marsh horsetail — Equisetum, from equus and seta.

Quick-fire facts

  • •Contains piperidine alkaloids, chiefly palustrine, that poison ruminants and horses; a 5% share in feed has been cited as causing severe poisoning
  • •Alkaloid concentration is highest in early growth, so early grazing of infested wet pasture is the greatest risk
  • •Common throughout Britain in marshes and wet meadows, with cone stems appearing June and July, according to NatureSpot
  • •Horsetails are not flowering plants: they reproduce by spores in cones and have no true leaves, only tiny scale-like sheaths
  • •The genus Equisetum is the sole survivor of a class that included the tree-sized Carboniferous calamites
  • •Similar-looking field horsetail is only mildly toxic, whereas marsh horsetail can be lethal
  • •Often grows alongside great horsetail in springline wet ground

Drill it — 6 cards

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Sources