THE CLUB MOSSES
As we have seen, the living species of the Club Mosses are comparatively
insignificant plants. None the less, most of them are attractive each in
its own way, and it is interesting to be able to identify the different
kinds. First of all we may consider the five species of Lycopodium.
_Lycopodium clavatum._ Here the generic name is derived from two Greek
words—_lukos_, “a wall,” and _pous_, “a foot.” One of the popular names
of the plant is Wolf’s Claw; possibly an allusion to the curious
branching-stem, although it must be confessed that the plant is not very
claw-like. The specific name is derived from the Latin _clava_, “a club”;
this having reference to the cones, or club, which bears the sporangia.
The Stag’s Horn Moss, or the Common Club Moss.
[Illustration: Lycopodium Clavatum. The Common Club Moss.]
This species has wiry stems of considerable length, sometimes measuring
as much as six or eight feet. These run along close to the soil, to which
they are attached at intervals by strong roots. The stems which branch in
all directions are covered with small narrow leaves, each of which ends
in a curious little bristle. This gives to the whole plant a singular
grey appearance. These hair-like points to the leaves may be regarded as
a distinct feature of the Common Club Moss. In the autumn the fruiting
spikes of the Common Club Moss are borne on the ends of erect stalks. The
cones are generally about an inch in length, and at times as many as two
or three of them may be allotted to each stalk. If closely examined it
will be found that the fruiting spikes are composed of a number of
leaf-like bracts, each one of which bears the case filled with spores.
After the dispersal of the spores the cones fall off, but the plant as a
whole remains green throughout the winter.
The Common Club Moss is often very abundant upon the moors of the North
of England, and also in Scotland and in Wales. On account of its creeping
habit of growth the plant is often overlooked, and few people realize
that this Club Moss is really very common. Sometimes single plants cover
huge areas of ground, and many of the trailing stems are several feet in
length. The spores of this, in common with those of other Lycopodiums,
are inflammable; and in the old days these were used in the manufacture
of fireworks.
_Lycopodium selago._ In this case the specific name of _selago_ was that
formerly given to all the Club Mosses. The Fir Club Moss.
This is a very pretty little plant, which, on account of its upright
habit of growth, attracts a good deal of attention. The stems vary from
about three to six inches in height, and these rise upwards from a main
stem which sometimes, but not always, trails along the ground for a short
distance. The branches are very thickly covered with leaves which overlap
one another, and are very stiff. Indeed, the whole plant is covered with
the foliage, which, being narrow and pointed, is almost bristle-like in
appearance. The colour of the foliage is bright green. The spore capsules
are present in the axils of the uppermost leaves of the branches, and
these are kidney-shaped. The Fir Club Moss is also very commonly
propagated by means of special little buds which appear at the tops of
the branches. When these are developed they fall to the ground, and give
rise to fresh plants.
The Fir Club Moss is probably almost as common as the Common Club Moss.
It should, however, be looked for on elevated moors and the slopes of
mountains.
[Illustration: Lycopodium selago. The Fir Club Moss.]
_Lycopodium inundatum._ Here the specific name has reference to the fact
that this Club Moss grows in situations which are often under water. The
Marsh Club Moss.
This is a peculiarly interesting species, in that it is the only British
Club Moss to be found in lowland districts. The stems of the plants are
prostrate, and these are so closely fixed to the soil with strong roots
that it is almost impossible to remove a specimen without taking away the
soil as well. The fertile branches rise in a very direct manner to the
height of two or three inches, and these, like the main stems, are
thickly covered with narrow leaves, which have sharp points. The
fructification is produced in the autumn, the capsules being borne
between leaf-like scales at the upper part of the shoot. A singular thing
about the Marsh Club Moss is that one end of the creeping stem is always
decaying, and an individual plant is rarely more than a few inches in
length. In the winter only the growing tip of the plant remains, and from
this the whole of the new development arises.
The Marsh Club Moss is comparatively rare in the North of England, though
in the South and West it is often to be found. As a rule it occurs in
large isolated patches, and one may hunt for some distance around before
finding any more specimens. It likes a thoroughly wet situation, and on
this account is soon stamped out when any schemes of land drainage are
undertaken.
_Lycopodium alpinum._ In this case the specific name is simply a
reference to the fact that this Club Moss grows in mountainous districts.
The Alpine Club Moss.
This species has long creeping stems which are rather bare of leaves.
From these, however, spring the upright branches which are thickly
covered with foliage; every one of the leaves terminates in a point. The
Alpine Club Moss is an evergreen plant, and it is of a very bright green
colour. The branches which bear the fertile spikes are somewhat taller
than the barren ones, and these are often twice forked. The cone bears a
number of thin scales, and between each of these and the stem is to be
found the kidney-shaped capsules.
The Alpine Club Moss is often to be found in great abundance in elevated
districts in Scotland and Ireland. It seems to be most happy in elevated
situations.
_Lycopodium annotinum._ In this case the specific name is from the Latin
term signifying “a year old.” This is an allusion to the fact that the
yearly additions to the plant are very evident. The Interrupted Club
Moss.
This species at first sight is sometimes taken for the Common Club Moss.
It is, however, readily distinguished when its branches are examined;
these are increased annually by an addition which is very plainly to be
observed. It is seen that at these periods the leaves are smaller and
much less inclined to spread than in the normal forms. At times the
branches divide, and at the tip of some of the upright shoots occur the
fertile cones. Each one of these is about an inch long, and it is covered
with bracts upon which the spore capsules are borne. The Interrupted Club
Moss is a fine species, and is of a pale green colour.
This is probably the rarest of our native Club Mosses. In some parts of
Scotland it is said to be abundant, but the plant is always a local one.
It has been found in the North of England, though it is decidedly
uncommon.
In the United Kingdom there is only one native species of Selaginella.
_Selaginella spinosa._ In this case the generic name is derived from the
name Selago; actually the name means “a little Club Moss.” The specific
name has reference to the tiny spines on the margins of the leaves. The
Lesser Alpine Club Moss.
This plant is, of course, very distinct from the Lycopodium, in that it
produces two kinds of spores. The Lesser Alpine Club Moss is a small
plant with both prostrate and upright stems. The leaves are very tiny,
and owing to their semi-transparent nature the whole plant is of a pale
green colour. Some of the upright stems are barren, but a certain
proportion bear the spore capsules in the axils of the small leaves. In
the upper part of the cone occur the capsules containing the microspores,
whilst in the lower portion are to be found the sporangia, each of which
produces three or four megaspores.
The Lesser Alpine Club Moss is probably more common than is generally
supposed, especially in the North of England. It grows in damp situations
and is often very much mixed up with other herbage, so that it is easily
overlooked. It is now necessary to describe the two or three curious
little plants which are closely related to the Ferns and Club Mosses.
_Isoëtes lacustris._ In this case the generic name originates in two
Greek words—_isos_, “equal,” and _etos_, “a year.” This has reference to
the fact that the plant keeps its leaves all through the year and does
not alter in appearance. The specific name _lacustris_ is derived from
the Latin word _lacus_, a lake, and is an allusion to the fact that the
plant grows in such a situation. The Quillwort.
This is an interesting little plant which is entirely aquatic in its
habits. The Quillwort has a tuberous root-stock, and from this arise a
large number of dark green leaves, somewhat resembling quills in shape.
These are about three or four inches in length, and when the plant is
growing in quantity in some pool, it is often taken for a kind of grass.
At the base of the leaves, partly protected by the sheathing, are to be
found the spore capsules. These cases are of two kinds, those on the
outermost rows of leaves containing the large spores, and those on the
inner leaves being responsible for the small spores.
[Illustration: Isoëtes lacustris. The Quillwort.]
The Quillwort is often abundant in mountain lakes in Scotland and the
North of England. Owing to its habit of growth, however, the plant is
usually unnoticed by the majority of people.
Another species of Quillwort—_Isoëtes Hystrix_—occurs in the Channel
Islands, but it has not been found elsewhere in the United Kingdom.
_Pilularia globulifera._ In this case the generic name is formed from the
Latin word _pilula_, “a little pill,” this being a reference to the
curious pill-like spore capsules which the plant produces. The specific
name of _globulifera_ is made up from two Latin words—_globus_, “a ball,”
and _fero_, “I carry.” This is another allusion to the rounded sporangia.
The Pillwort.
This is a curious little plant with a very slender creeping root-stock.
From this are sent down small tufts of roots into the damp soil in which
the plant grows. From the upper part of the stem arise the leaves, which
are bristle-shaped, two or three inches in length, and of an intensely
bright green colour. It is interesting to note that in their young state
these leaves uncoil very much in the same manner to be noticed in the
Ferns. The spore cases are situated at the point where the leaf arises
from the root-stock. Externally these are densely covered with brown
hairs, and they are just about the size of a small pea. The sporangia are
four-celled, and when the time for the dispersal of the spores arrive,
the cases split open. The spores are of two kinds, and both sorts are
present in the same sporangia. The large spores are confined to the lower
portion of the case, the small ones to the upper part.
The Pillwort is common in some parts of England, though less so in
Scotland and Ireland. It always grows in very damp situations, though it
is rarely found submerged, save when this happens as the result of
flooding. The Pillwort so often grows mixed up with grass, which in some
ways it resembles, that the plant is frequently overlooked.
[Illustration: Azolla caroliniana.]
_Azolla caroliniana._ Here the generic name is derived from two Greek
words—_azo_, “to dry,” and _ollo_, “to kill”—an allusion to the fact that
dryness is fatal to the well-being of the plant. The specific name has
reference to the fact that the plant is very abundant in Carolina, though
as a matter of fact it occurs in other parts of the world. It should be
pointed out that the Azolla is not a native of the United Kingdom, but it
has become well established in some parts of the South of England.
During the summer time the Azolla, which is a floating plant, increases
with great rapidity, sometimes completely covering the surface of a lake.
At first the fronds, which are exquisitely beautiful, are of a
silver-green colour; towards the autumn they assume a bright crimson
tint. Underneath the fronds are produced a large quantity of roots which
hang down into the water. Two kinds of spores are produced. The
microspores are packed away in cases which are provided with curious
barbed contrivances. The megaspores bear hooks, and in this way the two
processes become attached. The Azolla is a pretty plant to grow in an
aquarium, though where it has been able to make itself at home it will
sometimes increase so vigorously that all other vegetation is killed.