*SHOW The Equisetum species of the British Isles 
- 17 September 2004. 
 
*ITEM DESCRIPTIONS 
 
# \i{}Equisetum arvense\i0{} <L.>/
1<Common Horsetail> 3<dark brown to black, dull, hairy> 4,1<often,
these ovoid>/2 5,1<or rarely, the fertile stems persist and become
green> 6,10-25 7<about>,4-6<erect, smooth, somewhat succulent> 8,2
9,6-12 10<of assimilating shoots,>,20-80 11,3-5 12,1-2 13,1 14,2 15,1
16,2 18,6-19 19,2 21,1-2<from one third to two thirds its diameter> 22,2
23<pale> 24,1<(1-)3-8(-10) mm long, 1-9 mm wide> 26,6-19<as many teeth
as grooves, but the teeth often more or less cohering in pairs>
27<one>,1<the ribs reaching to their tips> 28<subulate, acute, green
with blackish tips> 30,1 31,2<about ten or twelve> 32,2-3
33<usually>,1<sometimes with a hint of secondary branching> 35,(3-)4
36,4<the teeth triangular-lanceolate, acuminate, somewhat spreading,
pale> 37,2 38,1 39,2 40,1-4 41,1 43<in>,1 45<Arctic and north temperate,
from Greenland to S. Spain, Crete, central China, Virginia, Alabama and
California. Common throughout the British Isles, in fields, hedgebanks,
waste land, dune-slacks, etc., ascending to nearly 1000 m> 46,1 47,3
49<arvense> 
 
# \i{}Equisetum fluviatile\i0{} <L.>/
1<Water Horsetail> 2<\i{}E. limosum\i0{} L.; \i{}E. heleocharis\i0{}
Ehrh.> 3<light brown, glabrous, smooth, with black roots> 4,1<according
to Le Maout & Decaisne>/2<according to Goebel> 5,3 10,50-140 11,2-12
12<more or less>,1 14,3 15,1<around the middle>/3 16,2 18,10-30 19,1
20,2 21<much>,3<4/5 or more> 22,1 23<green> 25,1-2<somewhat loose>
26,10-30<as many as the grooves> 27,2 28<subulate, small (about 1 mm),
black tipped> 30,2 31,2 32,1 33<when present,>,1<slender, ascending>
34<usually>,5 36,4-5<the teeth moderate, subulate, green or blackish>
37<about as long as or shorter than the subtending sheaths> 38,2 39,2
40,1-2 41,1 43,3-4 45<Europe, from Iceland and arctic Russia to central
Spain, Italy, Macedonia and the Caucasus; temperate Asia; North America,
from Labrador and Alaska to Virginia and Oregon. Common throughout the
British Isles, in shallow water at edges of ponds and lakes and in
ditches, less often in fens and marshes, ascending to almost 1000 m>
46,1 47,1 49<fluviati> 
 
# \i{}Equisetum hyemale\i0{} <L.>/
1<Dutch Rush, Scouring Rush> 4,2 5,3 10,30-100 11,4-6 12,1
13,2<glaucous> 14,1<on the ridges, these with two regular rows of
tubercles> 15,3 16,1 17,1 18,10-30 19<moderately deep> 20,2 21,2-3<2/3
or more> 22,3 23<soon whitish, black-banded at top and bottom> 24,1<3-9
mm> 25,2 26,10-30<as many as the grooves> 29,2<leaving the sheaths with
crenulate upper edges> 39,1 40,8-15 41,2 43,4-5 45<Europe, from Iceland
and northern (not arctic) Russia to central Spain, Corsica, northern
Italy, Crete and the Caucasus; northern and central Asia; and western
North America south to California and New Mexico. In Britain, from
Somerset and Kent to Sutherland, very rare in southern England and
Wales, scattered over Ireland. In shady moist places, to about 550 m>
46,2 49<hyemale> 
 
# \i{}Equisetum\i0{}  \i{}litorale\i0{} <Khlew. ex Rupr.>/
4<often(?)>,1 5,3 10,50-140 11,2-12 12,1 14,2 15,1 16,2 18,10-30 19,1
20,2 21,1-2<1/3 to 1/2> 22,1 23<green> 25,1<the upper sheaths with
dilated mouths> 26,10-30<as many as the grooves> 27,2 28<appressed,
black tipped> 30,1-2<?> 31,2 32,1 33,1<slender, ascending> 34,5<with 4
or five subulate, green or blackish teeth> 36,4-5<?> 37,1-2 38,2 39,2
40,0.5-1 41,1 42,2 44<stems more deeply grooved than in \i{}E.
fluviatile\i0{}, with twice the number of green bands, and more
branches> 45<occurring sometimes, and then often abundant, where both
parent species are present> 46,1 47,1 48<\i{}E. arvense\i0{}  \i{}E.
fluviatile\i0{}> 49<litorale> 
 
# \i{}Equisetum\i0{}  \i{}moorei\i0{} <Newm.>/
2<\i{}E. occidentale\i0{} (Hy) Coste> 4,2 5,3 10,30-100 11,4-6 12,1
13,2<glaucous> 14,1<on the ridges, these with two regular rows of
tubercles> 15,3 16,2<at least, to near the base> 17,2 18,10-30
19<moderately deep> 20,2 21,2-3<about 3/5> 23<soon whitish, black-banded
at top and bottom> 24,2 25<somewhat>,1 26,10-30<as many teeth as
grooves> 29,1<at least, more so than in \i{}E. hyemale\i0{}, dark brown,
truncate> 39,1 40,8-15 41,2 42,2 45<western and central Europe, the
detailed distribution uncertain owing to problems of identification. In
the British Isles, known from maritime dunes and banks in Wicklow and
Wexford, and from one locality in Surrey> 46,2 48<\i{}E. hyemale\i0{} x
\i{}E. ramosissimum\i0{}> 49<moorei> 
 
# \i{}Equisetum palustre\i0{} <L.>/
1<Marsh Horsetail> 4<often(?)>,1 5,3 10,10-60 11,1-3 12,1/2 14,2
15,1<usually, but often irregularly>/2/3 16,2 17,2 18,4-8 19,2 20,2
21<much>,1<small, scarcely larger than the outer canals> 22,2 23<green>
24<4-12 mm> 25,1 26,4-8 27<one>,1 28<triangular-subulate, blackish, with
narrow, whitish-scarious margins> 29,1<?> 30,1-2<often irregular> 31,1-2
32,1-2 33,1<spreading to sub-erect, often short> 34<4-5 grooved> 35,4-5
36,4<these short, appressed, black-tipped> 37,1 38,2 39,2 40,1-3 41,1
43,2-4 45<Europe, from Iceland and northern (not arctic) Russia to
central Spain and northern Portugal, Sicily, Greece and the Caucasus,
temperate Asia; and North America, from Newfoundland and Alaska to
Connecticut and Oregon. Common throughout the British Isles, in bogs,
fens, marshes and wet heaths, woods and meadows, ascending to nearly
1000 m> 46,1 47,1 49<palustre> 
 
# \i{}Equisetum pratense\i0{} <Ehrh.>/
1<Shady Horsetail> 2<\i{}E. umbrosum\i0{} Meyer ex Willd.> 3<black,
dull, hairy only on the sheaths> 4,2 5,2
10,20-60<sterile>/20-25<fertile> 11,1-2<measurement available only for
sterile stems>/- 12,1 13<green> 14,1<in sterile stems>/- 15,1<the
sterile stems, sometimes also in the mature fertile stems>/3<fertile
stems, commonly> 16,2 18,8-20 20,2<in sterile stems>/- 21,2-3<about half
or rather more, according to Clapham \i{}et al\i0{}.>/- 22,2 24<3-8 mm
long in sterile stems> 26,8-20<on sterile stems>/10-20<on fertile stems>
28<of sterile stem sheaths brown with a blackish rib, acute, subulate in
sterile; those on sterile stems pale with dark ribs> 29,1 30,1 31,2
32,2<usually>/2-3 33,1<and numerous, in both fertile and steriles stems>
35,3(-4) 36,3(-4)<the teeth deltoid, acute> 37<of
sterile stems>,2<though sometimes shorter on the lower parts of the
stem>/- 38,1 39,2 40,1.5-4 41,1 43<in>,1 44<the identity of Sowerby &
Johnsons illustration of \i{}E. umbrosum\i0{} needs checking, in view
of the erecto-patent branching and blunt-topped shape of the sterile
stem depicted> 45<Europe, from Iceland and arctic Russia to eastern
France, Tirol, Rumania and the Caucasus; northern and central Asia, and
North America from Nova Scotia and Alaska to New Jersey and Colorado. In
the British Isles, in scattered (mainly eastern) localities from
Yorkshire and Westmorland to Orkney, and in Ireland in Fernanagh,
Donegal and Antrim. Grassy stream banks, etc., ascending to about 1000
m> 46,1 47,2 49<pratense> 
 
# \i{}Equisetum ramosissimum\i0{} <Desf.>/
4,2 5,3 10,50-75 13<greyish green> 14,1-2<with scattered tubercles>
15,1<at least on their lower halves> 16,1 17,2 18,8-20 19<moderately
deep> 20,2 21,2-3<1/2 to 2/3> 22,3 23<green at first, then brown with a
black band at the bottom> 24<about 8 mm long> 28<black, with narrow
white margins and a hairlike apex> 29,1 31,2 37,1<about a third its
length> 38,2 39,1 40,0.6-1.2 41,2 43,2-5 44<the available descriptions
are poor> 45<Europe from Loire, southern Bavaria and central Russia
southwards, and in isolated localities in Brittany, the Netherlands, and
northern Germany; Asia, Africa and America. In Britain, first found on a
grassy stream bank near Boston (S. Lincolnshire) in 1947> 46,2
49<ramosiss> 
 
# \i{}Equisetum sylvaticum\i0{} <L.>/
1<Wood Horsetail> 3<light brown, smooth and shiny, hairy> 4,1/2 5,2
10,10-80<sterile>/10-40<fertile> 11,1-4 12,1 13,1 14,2-3 15,1<the
branches numerous, fewer and shorter on the fertile stems>/3<perhaps
occasionally, when fertile> 16,2 17,2 18,10-18<in sterile stems>/- 20,2
21,2-3<a half to two thirds> 22,2 23<green or greenish> 24<5-10 mm long>
26<ostensibly>,3-6<seemingly having joined teeth, these represented by
the 3-6 broad, subacute, brown lobes> 27<about 3>,1 29,1 30,1 31,2<10 to
16 or more per whorl> 32,3<towards their ends> 33<delicately>,2<at least
proximally, lending the plant its characteristic elegance> 34<3-4
grooved> 35,3-4 36,3-4<the teeth long, subulate> 37,2 38,1 39,2
40,1.5-2.5 41,1 43,1-2 45<Europe, from Iceland and Scandinavia to
northern Spain, northern Italy, Crete and the Caucasus; temperate Asia;
North America from Newfoundland and Alaska to Virginia and Iowa;
southern Greenland. Throughout the British Isles except for some midland
and southern counties and the Channel Isles; associated with acid soils
in damp woods and moors, ascending to about 1000 m> 46,1 47,2
49<sylvatic> 
 
# \i{}Equisetum telmateia\i0{} <Ehrh.>/
1<Great Horsetail> 2<\i{}E. maximum\i0{} auct.> 3<dark brown, rough>
4,1<often, these pear-shaped>/2 5,1 6,20-40 8,1 9,20-30 10<of
assimilating shoots,>,100-200 11,10-12 12,1 13<dirty whitish, with no
chlorenchyma> 15,1<these numerous, regular> 16,2 17,2 18,20-40 19,1 20,2
21,2-3<2/3 to 3/4> 22,2 23<pale, blackish above> 24<about 4 cm long>
25,1 26,20-40<as many as the grooves> 27<two>,1 28<blackish, subulate>
29,1 30,1 31,2 32,2 33,1<regular, spreading> 35,4 36,20-30<the teeth
dark> 37,1 38,1 39<on the sheaths>,2<the internodes lacking stomata, as
well as chlorenchyma> 40,4-8 41,1 43<in>,1 45<Europe, from Sweden,
Denmark and the Black Sea region southwards, Asia Minor and the
Caucasus; North Africa; Azores and Madeira; and north-western North
America from British Columbia to Ohio. In the British Isles, locally
distributed throughout England, Wales and Ireland, absent from
north-eastern Scotland; in damp, shady places, ascending to about 400 m>
46,1 47,2 49<telmatei> 
 
# \i{}Equisetum\i0{}  \i{}trachyodon\i0{} <A. Br.>/
1<Mackays Horsetail> 2<\i{}E. mackaii\i0{} Newman> 4,2 5,3 10,30-100
11,2-4 12,1-2 13<greyish green> 14,1 15,2/3 16,1 17,2 18,8-12
19<moderately deep> 20,2 21,1<about 1/3> 22,3 23<at first green with a
black band at the top, but becoming entirely black> 24<2-4 mm long> 25,2
27<four>,1 28<subulate, usually black> 29,1 33<when present,>,1 39,1
40<only about>,0.5<often deformed and partly abortive> 41,2 42,2
45<Iceland, Norway, Upper Rhineland; south-west Greenland; northern
temperate North America. Largely confined in the British Isles to
Scotland (Aberdeen and Kincardine by the Dee, and Perth), and Ireland
(widespread there, but absent from the centre and most of the
south-east); on shady banks of lakes and streams> 46,2 48<\i{}E.
hyemale\i0{}  \i{}E. variegatum\i0{}> 49<trachyod> 
 
# \i{}Equisetum variegatum\i0{} <Schleich. ex Web. & Mohr>/
1<Variegated Horsetail> 2<\i{}E. wilsonii\i0{} Newman> 4,2 5,3
10,15-60 11<very slender,>,1-3 12,2<commonly>/1-2 13<green> 14,2<the
ridges with two regular rows of minute tubercles> 15,2/3 16,1 17,2
18,4-10 19<moderately deep> 20,2 21,1<about 1/3> 22,3 23<green, black
banded at the top> 24<about 2-4 mm long> 25<rather>,1 26,4-10<as many
teeth as grooves> 27<four>,1 28<scarious, except for a blackish centre,
triangular- or ovate-lanceolate, at first subulate> 29,1<but the
subulate tip falling>/- 33<if present,>,1 39,1 40,0.5-0.7 41,2 43,4-5
45<Arctic and north temperate regions of Europe, Asia and North America,
extending from Greenland to the Pyrenees, northern Italy, Thrace,
Caucasus, Mongolia, Connecticut abd Oregon. Widespread in the British
Isles, on dunes, river banks, wet ground on mountains, etc., ascending
to about 500 m in Kerry (var. \i{}wilsonii\i0{} in Kerry only, usually in shallow
water)> 46,2 49<variegat> 

# \i{}Extinct Sphenopsida\i0{}/
5,- 42,- 49<sphenops> 1<Giant Horsetails, Articulates, Sphenopsids, Calamites> 
44<The Sphenopsida (= Equisetopsida, Arthrophyta), of which the 
16 species of \i{}Equisetum\i0{} are the the sole surviving representatives,
were represented by diverse herbaceous and woody forms, 
readily recognised by their characteristic jointed stems, associated 
with whorled leaves, branches and sporangia-bearing organs and correlated
with unique anatomy (see the examples illustrated). 
\i{}Equisetum\i0{} is referred to the Order 
Equisetales, which in Carboniferous forests were abundantly represented 
by the arborescent 
articulates commonly known as calamites. The general appearance of the more
impressive of these can readily be envisaged by imagining vegetative 
shoots of \i{}Equisetum arvense\i0{}, substantially
secondarily thickened and enlarged to about 16 m or more in height. By the early 
Mesozoic, these had apparently become extinct, with the rather scanty 
fossil record of Sphenopsida consisting by then mainly of casts and 
impressions of stems resembling those of modern \i{}Equisetum\i0{}. Given
the existence of late Paleozoic fossil fragments of plants seemingly 
closely similar to \i{}Equisetum\i0{} itself, it is evident that
the modern Horsetails exemplify persistence of a very ancient type.>

