categoryZHorsetails Horsetails List 
categoryZDeciduous Deciduous List 

WATER HORSETAIL

Equisetum fluviatile

Horsetail Family [Equisetaceae]

Sterile Stems: deciduous, ≤1.5m, ±branched centre, feels smooth
month8may month8jun month8june month8jul month8july month8aug month8sep month8sept month8oct month8nov


Fertile Stems: spores June, shorter & less branched
spores8jun

category
category8Horsetails
category
category8Deciduous
status
statusZnative
petals
petalsZ0
stem
stem8round
stem
stem8ribbed
toxicity
toxicityZmedium

5th June 2013, old gravel quarry, Little Lever, Gtr M/cr. Photo: © RWD
Standing in a pond it is the horsetail most fond of growing in the water, not just near the edges.


3rd June 2010, Walney Island, Cumbria. Photo: © RWD
Either no branches or whorls of branches mostly in the middle.


31st May 2008, Huddersfield Narrow Canal, nr. Slaithwaite. Photo: © RWD
These specimens are mostly branched. The stems are bright yellow-green.


23rd Aug 2010, Afton Marsh, IoW. Photo: (CC by 2.0) Mike Cotterill
Tall specimens all with cones and short leaves cum branches.


31st May 2008, Huddersfield Narrow Canal, nr. Slaithwaite. Photo: © RWD
Fertile stems are usually shorter than the sterile stems and less branched.


31st May 2008, Huddersfield Narrow Canal, nr. Slaithwaite. Photo: © RWD
When they are branched, the branches mostly occur in the middle of the stem.


23rd May 2013, North Hants. Photo: © Dawn Nelson
Young specimens with short leaves cum branches. The tube is so thin on water Horsetail as to be semi-translucent in places. There may even be the beginnings of a cone in this specimen; a conical shadow can be espied lurking near the top. And just below each whorl of leaves are more shadows of something else inside (the extension downwards of the sheaths?)


23rd May 2013, North Hants. Photo: © Dawn Nelson
This specimen has no shadow of a lurking cone to be seen.


23rd May 2013, North Hants. Photo: © Dawn Nelson
The thin grooves are also semi-translucent by transmitted light. Your Author notes that both the branches and the sheath teeth are longer on one side than the other on this specimen - a consequence of more sun on one side perhaps?


23rd Aug 2010, Afton Marsh, IoW. Photo: (CC by 2.0) Mike Cotterill
The fertile cones and whorls of short leaves/branches on this large group of Water Horsetail. [The long broad grass-like leaves are not of Water Horsetail].


23rd Aug 2010, Afton Marsh, IoW. Photo: (CC by 2.0) Mike Cotterill
A developing cone.


23rd Aug 2010, Afton Marsh, IoW. Photo: (CC by 2.0) Mike Cotterill
A more developed and elongating cone escaping the clutches of the top row of sheath-teeth.


5th June 2013, old gravel quarry, Little Lever, Gtr M/cr. Photo: © RWD
Fertile stems are less often branched. The young cones have the uppermost teeth cradling the lower part of the cone. Stems of fertile (here) or vegetative forms are smooth to the feel but do have very slight ridges, which number anywhere between 10 to 30.


5th June 2013, old gravel quarry, Little Lever, Gtr M/cr. Photo: © RWD
A cone becoming fertile. The cones are rounded at the top. The ridges on the stems are very low.


5th June 2013, old gravel quarry, Little Lever, Gtr M/cr. Photo: © RWD
The hexagonal structures will eventually near spores when ripe.


5th June 2013, old gravel quarry, Little Lever, Gtr M/cr. Photo: © RWD
The rounded tip of the cone.


5th June 2013, old gravel quarry, Little Lever, Gtr M/cr. Photo: © RWD
The sheath teeth tickling the cone. It is rather slack around the cone with a bit of a gap.


rd June 2010, Walney Island, Cumbria. Photo: © RWD


5th June 2013, old gravel quarry, Little Lever, Gtr M/cr. Photo: © RWD
A junction of 'stemlets'. Not all specimens have bright orange sections but it is often tinged orange especially on the fertile stems.


5th June 2013, old gravel quarry, Little Lever, Gtr M/cr. Photo: © RWD
The teeth of the sheath. There is very little presence of any roughness. The stems feel smooth.


5th June 2013, old gravel quarry, Little Lever, Gtr M/cr. Photo: © RWD
The central hole in the stems is large in comparison to the thickness of the outer 'skin'. Your Author just broke the stem in half, he doesn't use a knife (too dangerous to carry around in a rucksack or too heavy if a safety Stanley Knife).


Easily mistaken for : Marsh Horsetail (Equisetum palustre) but on that the cones are pointed (rather than rounded at the summit); the central hollow is very small in comparison to the stem diameter; it is shorter with a max height of just 60cm (half the maximum height of Water Horsetail); has fewer ridges - between 4 to 9, max 12) (as opposed to 10-30 of Water Horsetail). There are other subtle differences too.

Hybridizes with : Flower ()

  • Field Horsetail (Equisetum arvense) to produce Shore Horsetail (Equisetum × littorale) which is the commonest of the horsetail hybrids, frequently occurring near the parents and usually by the sea.
  • Marsh Horsetail (Equisetum palustre) to produce Equisetum × dycei which is intermediate in character.
  • Shady Horsetail (Equisetum pratense) to produce Equisetum × mchaffiae which is found in Caithness.
  • Great Horsetail (Equisetum telmateia) to produce Equisetum × willmotii which was found in County Cavan.
It is not known if any of the photos here are of any hybrids, but is maybe unlikely as none of these specimens were anywhere near the sea (which is where the commonest hybrid is usually found)


  Equisetum fluviatile  ⇐ Global Aspect ⇒ Equisetaceae  

Distribution
 family8Horsetail family8Equisetaceae

 BSBI maps
genus8Equisetum
Equisetum
(Horsetails)

WATER HORSETAIL

Equisetum fluviatile

Horsetail Family [Equisetaceae]