categoryZHorsetails Horsetails List 
categoryZDeciduous Deciduous List 

GREAT HORSETAIL

Equisetum telmateia

Horsetail Family [Equisetaceae]  

Sterile Stems: very tall <2m, whitish; 18-40 simple branches in dense whorls
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Fertile Stem: Spores, stems brown, annual, before sterile stems
month8apr month8april

category
category8Horsetails
 
category
category8Deciduous
 
status
statusZnative
 
petals
petalsZ0
(0)
stem
stem8round
 
stem
stem8ribbed
18-40
stem
stem8hollow
 
toxicity
toxicityZmedium
 

4th April 2011, airport, Sandown, IOW Photo: (CC by 2.0) Geoff Toone
Fertile stems en masse beside a road.


3rd May 2013, Consall Forge, Caldon Canal, Staffs. Photo: © RWD
Forms large patches near water or in damp ground, especially on clay. These are the sporing fertile stems. Fertile Stems here, which usually come before the entirely separate sterile stems.


3rd May 2013, Consall Forge, Caldon Canal, Staffs. Photo: © RWD
Fertile stems. Grows in damp places often near water, but never in water; that would be Water Horsetail (or a similar plant, Mare's-tail).


3rd May 2013, Consall Forge, Caldon Canal, Staffs. Photo: © RWD
Fertile Stems. At first the fertile spike arises from the ground. The fertile stems are brown and without branches (unlike the sterile stems which can be branched and are bright-green with nearly white internodes).


3rd May 2013, Consall Forge, Caldon Canal, Staffs. Photo: © RWD
Fertile Stems. The light-green stem of the fertile spike has regularly-spaced sections with brown/black whorls, the toothed sheaths.


2nd April 2014, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
Fertile Stems. As it grows the individual sporing bodies become separated.


3rd May 2013, Consall Forge, Caldon Canal, Staffs. Photo: © RWD
Fertile Stems. The tip of the stem has an extended pale-green progressing through pale-fawn to brown tip, a colour and shape unlike any other Horsetail. This is a cone and is covered in small flat-topped short projections not un-like those on some table-tennis bats which bear the spores. The projections start off at the bottom in ordered rings but quickly degenerates into a random arrangement.


2nd April 2014, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
Fertile Stems. Each individual sporing 'floret' is quite long, and is supported by several green cylindrical structures, the spore-sacs. The assembly has a totally differing appearance to that of the very similar Field Horsetail.


2nd April 2014, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
Fertile Stems. The green structures merge at the top into a single sporing body. Note the efficient mostly hexagonal packing.


2nd April 2014, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
Fertile Stems. And immature ones are white?


Photo: (CC by 2.0) Geoff Toone
This fertile stem is sporing.


Photo: (CC by 2.0) Geoff Toone
The spores are contained within the stubby projections from the disc at the tops of the much thinner stalks (for their narrower stalks - see far left)


3rd May 2013, Consall Forge, Caldon Canal, Staffs. Photo: © RWD
Fertile Stems. The toothed sheaths overlap at first but become separated as the fertile spike grows taller.


24th July 2013, a swamp, Moses Gate Country Pk, Gtr. M/cr. Photo: © RWD
Sterile Stems. In a swamp surrounded by tall trees and high weeds around it it has to grow even taller to reach much light.


15th June 2004, Rowsley moor wood, Rowsley, Derbyshire. Photo: © RWD
Sterile Stems. Only after the fertile spikes have spored do the branched infertile stems grow. They are like green bottle-brushes, up to 2m in height.


2 Aug 2005, Parbold, Leeds & Liverpool Canal. Photo: © RWD
Sterile Stems. The stem is again in sections and is very pale green.


2 Aug 2005, Parbold, Leeds & Liverpool Canal. Photo: © RWD
Sterile Stems. Each section has a toothed sheath, but un-like the fertile stalk also has a whorl of wire-like green leaves.


24th July 2013, a swamp, Moses Gate Country Pk, Gtr. M/cr. Photo: © RWD
Sterile Stems. In a dark swamp underneath trees the internode part of the stems is still a little green, but the further up the stem it is and able to catch the light better the paler it is; it is the leaves which do most of the photosynthesis, the internodes are only peripheral collectors of sunlight on Great Horsetail.


28th Aug 2011, Eire. Photo: © Paula O'Meara
Older Sterile stems: the main stems (nearly white) main stems have extended more and the leaves have grown much longer. This specimen has tapered sections of the stem.


4th Oct 2018, Macclesfield Canal, nr Whitley Green, Cheshire Photo: © RWD
Sterile Stems (young). The leaves, get very long on older specimens, are in a whorl just below each bright-green sheath, with the teeth just above the sheath.


13th May 2018, next the sea, Cliff End, Pett, Sussex. Photo: © RWD
Sterile Stems (young). Growing right opposite the sea and possibly washed by sea-splash in storms.


13th May 2018, next the sea, Cliff End, Pett, Sussex. Photo: © RWD
Sterile Stems (young). Here only the bright-green sheaths of the stems are showing; when it grows more the nearly-white but longer internode tubes will also be visible growing within the sheaths. The leaves, which are un-branched, are in dense whorls.


3rd May 2009, Newbridge, IOW. Photo: (CC by 2.0) Mike Cotterill
A young still extending sterile stem.


13th May 2018, next the sea, Cliff End, Pett, Sussex. Photo: © RWD
Sterile Stems in various degrees of growth - mostly only the bright-green sheaths are yet visible; the nearly-white intervening internodes are yet to extend.


13th May 2018, next the sea, Cliff End, Pett, Sussex. Photo: © RWD
Sterile Stems (young). The bright-green leaf sheaths (mostly all that is visible on this still extending specimen) may (or may not) have black bands (here without). The sheath teeth are long like eyelashes.


13th May 2018, next the sea, Cliff End, Pett, Sussex. Photo: © RWD
Sterile Stems (young). The nearly-white internode tubes are still extending here and often >1cm in diameter and with between 18 to 40 barely discernible ridges. The teeth on the tops of the bright-green sheathes have turned white here and look a bit worse for wear.


13th May 2018, next the sea, Cliff End, Pett, Sussex. Photo: © RWD
Sterile Stems (young). The leaves are numerous, unbranched and in short sections


13th May 2018, next the sea, Cliff End, Pett, Sussex. Photo: © RWD
Sterile Stems (young). Two new shoots emerging from the earth, conical in shape, with only the sheath teeth bared at the moment. The plant extreme left has many new leaves in dense whorls just starting to grow.


13th May 2018, next the sea, Cliff End, Pett, Sussex. Photo: © RWD
Sterile Stems (young). The sheath teeth are long, eyelash-like and often stuck together in small groups. The stem is very hollow, the rim being very thin. Just trapped between the lower sheath and the hidden internode which has not grown long yet are some new leaves just poking their tips out.


4th Oct 2018, Macclesfield Canal, nr Whitley Green, Cheshire Photo: © RWD
Sterile Stems (young). Your Author can testify that the sections of Great Horsetail are not easily parted at all; after several unsuccessfull attempts at pulling it apart, this is the best he could do without access to a knife. It has torn the two walls of the hollow stem away in places, but otherwise the channels are intact on the far side. Your author presumes the nutrients and water go up these channels rather than up the much larger central hollow.


Some similarities to : Mare's-tail (Hippuris vulgaris), which grows in shallow water, has whorls of wiry leaves which are shorter than those of Horsetails and which belongs to a differing family (Hippuridaceae).

Hybridizes with:

  • Field Horsetail (Equisetum arvense) to produce Anglesey Horsetail which only occurs in one hectad of Anglesea.
  • Water Horsetail (Equisetum fluviatile) to produce Equisetum × willmotii which occurs in but a handful of hectads in the UK.
  • Marsh Horsetail (Equisetum palustre) to produce Equisetum × font-queri which occurs mainly in Lancashire.
  • Wood Horsetail (Equisetum sylvaticum) to produce Equisetum × bowmanii which occurs in only 3 hectads in the UK.
The fertile stems shown in the above photos, taken in Staffordshire, are un-likely to be hybrids, since none occur in the area.

Uniquely identifiable characteristics

No relation to : Horse-radish, Horse-Chestnut, Horseshoe Vetch (Hippocrepis comosa) nor to Horse Mint (Mentha longifolia) [plants with similar names belonging to differing families]

The fertile spikes are without leaves and appear before the infertile spikes bearing whorls of wire-like green leaves. Both stalks and leaves are in sections which, if pulled hard, will part company. Great Horsetail is the tallest Horsetail, and easily recognised by the fawn-coloured long tip of the fertile spike bearing the spores. It is by far the tallest Horsetail, the sterile light-green stems with whorls of wire-like leaves growing to 2m. It grows near water or in damp ground but never in the water as does Water Horsetail (Equisetum fluviatile).

The branches of the photosynthetic (aka sterile) stems are 8-angled [as opposed to 3-angled for Shady Horsetail (Equisetum pratense); 4-angled for Wood Horsetail (Equisetum sylvaticum) and for Field Horsetail (Equisetum arvense); 5-angled for Variegated Horsetail (Equisetum variegatum); and 6- to 7- (up to 10)-angled for Branched Horsetail (Equisetum ramosissimum)]

The main stems, on the other hand, usually have more ridges: On Great Horsetail they number between 18-40 (up to 60) and are faint grooves.

The horsetails are very primitive non-flowering spore-bearing plants. Like Ferns, such as Bracken, Horsetails also contain Thiaminases which eliminate Vitamin B1 (Thiamine) from the body, causing disease.

A TOXIC POLYCYCLIC PEPTIDE ALKALOID

Horsetails are poisonous and many contain much the same toxins, such as Palustrine, but in differing proportions. Great Horsetail is more toxic than most, having higher concentrations of the toxins.

Palustrine (aka palustrin) is a polycyclic peptide that can gum up the workings of the normal mammalian body if ingested, such as by sheep, oxen or cows but especially by horses, when the intoxication is then called equisetosis. The characteristic symptoms are breathing disorders, digestive problems and possibly fever. The alkaloids exhibit oxytocic properties, where females can lose their off-spring, which can also happen to pregnant women who consume Horsetail plants. Marsh Horsetail (Equisetum palustre) has an especially high concentration of Palustrine, hence the name of the alkaloid. Marsh Horsetail (and possibly other horsetails too) also has derivatives of Palustrine, such as N-FormylPalustrine, N-AcetylPalustrine, Palustridiene and N-FormylPalustridiene. All contain a lactam ring. On alkali fusion Palustrine yields Spermidine.

[There is another molecule with the same common name as Palustrine which is not related in any way to the above - that is the problem with common names]


  Equisetum telmateia  ⇐ Global Aspect ⇒ Equisetaceae  

Distribution
family8Horsetail family8Equisetaceae

 BSBI maps
genus8Equisetum
Equisetum
(Horsetails)

GREAT HORSETAIL

Equisetum telmateia

Horsetail Family [Equisetaceae]  

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