THE HORSETAILS
It is now necessary to consider a very striking order of plants. Unlike
the Club Mosses, it is probable that most people are familiar with one or
more species of Horsetail; some of these plants are not only common, but
they are also very striking in appearance. In all there are eight species
of _Equisetum_ which are natives of the United Kingdom, and most of these
are fairly easy to identify if a few leading features are borne in mind.
_Equisetum arvense._ The generic name in this case is composed of two
Latin words—_equus_, “a horse,” and _seta_, “a bristle.” Thus we see that
the popular name of the plant is an almost exact translation of the
scientific one. The specific name is derived from the Latin adjective
_arvus_, “a field,” and has, of course, reference to the fact that the
plant grows in pastures. The Field Horsetail.
[Illustration: Barren stem of Equisetum arvense.]
This species is by far the commonest of all the Horsetails, and is very
frequently to be found on embankments in fields and by the sides of
roads. The plant, which dies down in the winter, starts its growth quite
early in the year with the development of the fertile stems. These rise
straight up from the branching root-stock, and are generally about five
or six inches in height. The stem, which is of a very pale colour, is of
rather a succulent nature; it is hollow in the centre and in a certain
way reminds one of bamboo. At intervals there are certain sheaths which
are divided into a number of teeth with very sharp points. The cone-like
fructification is about an inch in length and bears a number of peltate
scales to which the spore capsules are attached. The spores are ready for
dispersal in the month of May. Just about this time the barren stems put
in an appearance. These rise to the height of two feet, or even more, and
have many whorls of spreading branches which in their turn may again be
branched. It is these branches which carry on the real vegetative work of
the plant. For the real leaves we must examine the sheaths, which with
their wedge-shaped teeth are to be found at the stem joints. The teeth
are the only free portions of the leaves of the Horsetails. It is
interesting to note that in each whorl the branches are equal to the
number of leaves and are alternate to them. The stem of the barren
branches of the Field Horsetail is slightly marked with furrows, which
vary in number. The branches are usually only four-furrowed, and have
sheaths with the same number of teeth.
The whole of the barren portion of the Field Horsetail is very rough to
the touch. This is due to the fact that the plant is covered with tiny
flinty particles. That the measure has a protective value is very
evident, for cattle have hardly ever been known to eat the plant.
_Equisetum maximum._ In this case the specific name, of course, means
great, and has reference to the fact that the species is the largest of
all the kinds. In some old books this species is given as _E. Telmateia_
and _E. fluvialis_. The Great Horsetail.
[Illustration: Fertile cones of Equisetum maximum.]
This is by far the most striking of all our native Horsetails. As a rule
the plant grows in a damp situation, and it then assumes handsome
proportions. The fertile stems appear on the scene about April, and these
do not as a rule exceed a foot in height. They are very succulent, and
have loose sheaths which have about thirty or forty teeth. The sheaths
are green at the lower, and brown at the upper part, being distinctly
marked with lines. The fertile cones are three or four inches long and
possess a very large number of scales. The barren stems are remarkable
for their erect growth, and in a fine specimen these may be four or five
feet in height. The stem bears numerous whorls of branches, and these
branches may show yet further divisions. As a rule each whorl has thirty
or forty branches apiece. On the upper part of the stem the whorls are
very close together, but they are more widely separated at the lower
portion. The main stems, which taper towards the apex, are marked with
lines, and at intervals are enclosed in sheaths; these have long teeth
and fit the stem very closely. The branches are rough to the touch, and
have sheaths which end in four or five teeth; each tooth in this case is
prolonged into a bristle which has two toothed ribs. This is a feature by
means of which it is always possible to distinguish the Great Horsetail
from any other species. Now and again stems have been found which, whilst
bearing fertile cones, at the same time branch in the manner to be
observed in the case of the barren stems.
The Great Horsetail is widely distributed and is sometimes very abundant,
though it is not so common as some of the other species of _Equisetum_.
_Equisetum pratense._ In this case the specific name is a Latin word
which means “growing in a meadow.” In some books this plant is known as
_E. umbrosum_. The Shade or Blunt-topped Horsetail.
This species has three kinds of stems. The first of these is about six
inches in height, and is provided with large loose sheaths. This bears
the cone of fructification, which is ripened about the month of April.
The second type of stem produces both branches and a fertile cone, though
this latter is very much smaller than in the case of the first type of
stem. Finally, there is the barren stem, which may be about eighteen
inches in height; this is very rough, and has about twenty
strongly-marked ridges. The sheaths, which are not so large as those of
the fertile stem, fit somewhat closely. The stem branches freely, and it
is to be noted that these branches have three or four ridges; as well,
they bear sheaths which end in the same number of teeth. A distinctive
feature of the Shade Horsetail is that the topmost whorls of branches
spread upwards in such a way that they reach the summit of the stem;
there is no long tapering point such as is to be seen in the case of the
Field Horsetail, for instance. The result of this habit of growth is that
the plant has a curious flat-topped appearance; it is on this account
that the species has received one of its popular names.
The Shade Horsetail grows in damp meadows and very shady woods, though it
is not common in all districts.
_Equisetum sylvaticum._ In this case the specific name is taken from the
Latin _silva_, “a wood,” and is a reference to the habitat of the plant.
The Wood Horsetail.
This is one of the most beautiful of our Horsetails. The plant has two
kinds of stems, both of which are ultimately branched. The fertile stems
put in an appearance first of all in the early spring; at this time these
bear only a cone and are without branches. With the dispersal of the
spores the cone shrivels up, and then the stems starts to send out green
branches. These branches give off whorls of smaller branches from their
joints. In a general way the stems of the barren shoots are not so
succulent as those which bear the cone; the barren stems, too, are
somewhat taller and branch more freely than the fertile ones. In both
barren and fertile stems are to be noticed the whorls of small drooping
branches which give a characteristic appearance to the Wood Horsetail,
and by means of which it may always be identified. The sheaths which
enclose the stem evidence three or four teeth, whilst the terminal
branches (which are three-ribbed) bear at each joint a sheath ending in
three long pointed teeth. The stems of the Wood Horsetail are marked by
about a dozen ridges.
The Wood Horsetail is often abundant in damp shady woods.
_Equisetum palustre._ The specific name _palustre_ means “belonging to
the marshes.” The Marsh Horsetail.
This plant has a very thick rhizome from which arise the erect stems. The
barren and the fertile stems closely resemble each other, being about a
foot or more in height, with very rough surfaces on which it is possible
to count from six to twelve very prominent ridges. The stems are enclosed
at intervals in loose sheaths, which have the same number of teeth as the
ridges on the stem. It should be noted that the branches from the various
whorls show a marked tendency to turn upwards. On certain of the stems
the fertile cone appears and the spores are ripened about June, after
which the process withers. The plant as a whole remains green until late
in the autumn. Sometimes in the case of large plants, cones have been
known to occur on the tips of the branches of the Marsh Horsetail.
The Marsh Horsetail is a very common species, often growing in the
greatest profusion by the sides of pools.
_Equisetum limosum._ In this case the specific name is a Latin word which
means “full of mud”; this being an allusion to the fact that the plant
favours swampy situations. The Smooth Naked Horsetail. The plant is also
called the Water Horsetail.
A distinctive feature of this plant is that it has almost completely
smooth stems, though a close examination will indicate the presence of a
number of slight ridges. The barren and the fertile stems are very
similar, and in a favourable situation they will grow to the height of
two or three feet. A curious feature of this plant is the irregular way
in which the branches appear. Sometimes the stems are quite bare; on
other occasions they are partly branched; in any case the branches are
short. The sheaths with many teeth are closely pressed to the stem. The
fertile stem is, of course, distinguished by the cone which it bears at
the summit. It is said that cattle are not averse to eating the Smooth
Naked Horsetail, and certainly the stems are not unpleasant to the touch.
The Smooth Naked Horsetail is a common plant, specially by the sides of
streams and pools. It sometimes grows right in the water.
_Equisetum variegatum._ Here the specific name means variegated, and has
reference to the fact that the sheaths enclosing the stem are pale green
below and blackish in colour above. The Variegated Rough Horsetail.
As a rule this plant grows by the seashore, where, by means of its
fibrous roots, it may play a useful part in helping to bind the shifting
sand. The Variegated Horsetail is not exclusively maritime, however, for
it sometimes grows by the sides of rivers and ponds. The barren and
fertile stems closely resemble one another, and they are very nearly
prostrate in habit. As a rule they are about a foot in height, and the
stems have from four to ten ridges. The upper part of the stem is usually
unbranched, but whorls of branches occur towards the base. The sheaths,
which, as already stated, are green below and black above, fit very
closely to the stem. The black teeth have white margins, and terminate in
bristle-like points. The cones are borne at the summit of the fertile
stems, and are comparatively small.
The Variegated Rough Horsetail occurs chiefly, though not exclusively, in
the North of England.
[Illustration: Equisetum hyemale. The Dutch Rush.]
_Equisetum hyemale._—In this case the specific name is a Latin adjective
which means “pertaining to winter,” an allusion to the fact that the
plant is to be found all through this season. The Rough Horsetail or
Dutch Rush.
This is quite the most distinct of all the Horsetails. There are none of
the whorled branches which are so familiar in the other species, and it
is only now and again that even a single branch is produced from the base
of one of the sheaths. There is a strong resemblance between the barren
and the fertile stems. These are both tall and very erect, usually
running up to the height of two or three feet. The stem is very rough to
the touch, and is marked with from fourteen to twenty ridges. The edges
of these ridges are thickly covered with flinty particles. The sheaths of
the Dutch Rush clasp the stem of the plant very closely. The fertile cone
is small, and is placed at the top of the stem.
The Rough Horsetail is not a very common species, but is abundant on the
Continent, especially in Holland and Germany, where it is largely
employed for the fixing of the soil of embankments. The Rough Horsetail
is very useful for polishing wood.