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THE
PLANTS OF THE GRASSY PASTURES
The
grassy pastures are composed for the larger part of certain grasses such
as the Sheep’s Fescue (Festuca ovina) and the Matgrass (Nardus
stricta). Besides these grasses man y species of sedges and rushes
occur especially in damper areas. Naturally, heather and crow-berry cover
large areas of the mountain slopes, but where they occur we have typical
moorland vegetation and hence I shall deal with these species in the
chapter entitled ’Moorlands’.
Several
species of flowering plants are also found n the grassy pastures. They
have to contend with difficult problems of seed distribution due to the
fact that the grasses tend to colonize vast areas to the exclusion of the
other species. We shall find that plants living in the grassy pastures
are perennial and, by means of climbing or tall stems, overtop the grasses
in order to display their flowers well above the grassy screen.
 Yellow Mountain Violet (Viola lutea)
One of
the most beautiful plants to be found in the grassy mountain pastures of
the western Highlands is the Yellow Mountain Violet. It is one of the
loveliest species and is a very interesting plant.
It
possess a short, underground stem in which food reserves are stored. This
stem branches and hence can give rise to several plants, leaves and
flowers being produced from buds at the tip of each branch. In order to
colonize as much land as possible, the rhizome gives rise to long,
creeping stems called runners; these pass between the stems of the grasses
and other plants and so reach favourable places at considerable distances
from the parent plant. It then sends out roots into the soil from its
nodes. Once these have penetrated the soil, leaves are produced and
eventually flowers. In time the portion of the runner connecting this
daughter plant to the parent dies and so an independent plant is formed.
This in time sends out runners and so eventually large areas are
colonized.
As a
further aid to invasion of new territory, the fruit of the violet have a
special mechanism by which the seeds are forcibly expelled to a
considerable distance. It will thus be realized that this plant is very
well equipped for the life struggle. To this must be added the beautiful,
highly specialized flower which are constructed for cross-pollination by
bees.
The lower
petal of the flower is much large than the others and acts as a landing
stage for the bee; it is also prolonged backwards as a spur in which the
nectaries are concealed. The spur can only be approached through a very
narrow passage between the stamens and the base of the petal. As if this
were not enough to deter unwelcome visitors, the bases of the petal are
hairy to further obstruct the entrance. Around the pistil are five
stamens which have short filaments and whose anthers are applied closely
to the top of the ovary below the stigma. They open inwards and their
pollen is drier than n most insect-pollinated flowers. The stigma is a
knob-like projection on the summit of the ovary, with a tiny flap
projecting downwards from the lower side. From the two lower stamens two
white nectarines project back into the spur.
When a
bee visit’s the flower it alights upon the lower petal and, guided by its
dark begins, pushes it had into the entrance of the flowers. On so doing,
any pollen on its head will adhere to the stigma which obstructs its way.
Its head will only go a short distance beyond the stigma, but then it is
below the anthers and as it pushes its tongue down to the nectaries, it
disturbs the stamens causing the dry pollen to rain down on its head.
There is
no danger of this pollen being left on the stigma as the bee withdraws its
head, because the tiny flap at the base of the stigma is forced up over it
and prevents any pollen touching it.
Through
this marvelous mechanism, the violet assures cross-pollination and makes
sure that its nectar will only be accessible to its particular benefactor.
The
violet also produces tiny green flowers, which never open. They contain
stamens and a pistil and are self-fertilized. These flowers are know as
cleistogamous flowers and are fairly common in the plant world, occurring
in the White Dead Nettle, the Balsam and Wood Sorrel in addition to the
Violet Family.
The
advantage to the plant of these flowers is that, if bad weather prevents
bees visiting the showy flowers, some seed is certain to set by the
cleistogamous ones. In the mountains this must often be the only seed
set.
The fruit
is a three-sided capsule and when ripe it becomes erect. On a dry sunny
day it splits into three by means of three valves. The seeds are then
collected into three boat-shaped compartments. The wall then dry and
contract, so squeezing the seeds together and eventually the inner ones
fly out, often to a considerable distance. As much as three feet has been
measured.
UMBELLIFEROUS PLANTS
Two
members of the great Umbelliferous Family are to be found in the Highland
pastures. They are the Spignel (Meum athamanticum) and the Sweet
Cicely (Myrrbis odorata).
They are
both very attractive plants and are highly aromatic; the leaves, stems and
rootstock containing sweetly smelling oils. The both possess large,
underground stems, which store up large quantities of foodstuff in the
form of starch and oily substances. This reserve allows them to commence
growth as soon as favourable weather returns in the spring.
They
produce a tuft of large leaves which are highly dissected. In the case of
the Spingnel, the leaf segments are almost hair-like, but the Sweet Cicely
they are very similar to those of the Common Cherbil or Cow Parsley so
common in the lowlands in spring and early summer. The tuft of spreading
leaves keeps competitors from encroaching upon the immediate surroundings
of the plant.
>From the
midst of the leaves arises a tall flowering stem, which in the case of the
Sweet Cicely may be three feet high and branched. The tall stems easily
overtop the grasses and other plants of the pastures. They are also very
strong with ribs of hard woody tissue running down the sides and they are
also hollow (and as we now tubular construction gives the greatest
strength with the least material). They are thus well able to support the
large flower heads and to withstand the wind which so often sweeps their
exposed habitat.
As the
summit of the stems and branches, are produced large heads of flowers,
constructed after the typical fashion of the Umelliers. From the summit
of the stem radiate several stalks or, as they are called, rays; in the
case of the Spignel there are ten to fifteen rays, whilst in the Cicely
there are rather more. Each ray reaches the same height and at its ummit
gives rise to a similar number of shorter rays, called the secondary
rays. Each of them produces a single flowers and as they reach the same
relative height the resulting head of flowers is a flat, table-like
structure. This form of flower head is called an umbel. In the above case
the flower heads are actually umbels are several spreading bracts which
help to impede creeping insects from reaching the flowers.
The
flowers are small with five white petals arranged around the fleshy summit
of the flattened ovary. This produces nectar quite openly upon its
surface and it is easily obtained by short-tongued insects. The large
numbers of flowers in each umbel make them very conspicuous and they are
visited by hosts of insects. Many kinds of lies, some beetles,
short-tongued bees, wasps, butterflies and hover-flies visit them At
first each flower is male only as the two stigmas are not mature until all
the pollen is shed. Large quantities of cross-fertilized seed are set.
Each
flower finally produces a single winged fruit containing two seeds. After
fertilization the ovary walls enlarge and produce a wing all round the
edge. The seed itself is surrounded by vessels containing aromatic oils
which help to nourish the embryo and protect it from damp. When ripe the
fruit splits down the middle and the wind transports the resulting halves
to a considerable distance supported by their wings.
It is
thus not surprising that the above two plants are common and well
distributed in the Highland pastures.
Viviparious Persicaria (Polygonum viviparous)
This
plant is quite common in grassy pastures and is closely related to the
Persicarias and Snake-weed of the lowlands.
It is a
lowly plant with a tuberous underground stem acting as a storage organ.
The stock
is crown by narrow leaves with very log stalks. They are smooth and
leathery in texture whilst the edges are recurved, thus covering, to a
certain extent, the under surface and preventing excessive transpiration.
The flower stems are about six inches high with a few small sessile
leaves. The flesh-colored flowers are produced in a close terminal spike
and are visited by flies and small bees, but are often self-fertilized.
Very
often, however, it will be noticed that the lower flowers are reddish,
bud-like objects. These are bulbils, which are easily detached and, on
falling to the ground, produce roots and leaves. This known as vegetative
reproduction or as it is sometimes called, vivipary. The advantage of
this to the plant is, that the long period of time between the opening of
the flowers to the setting of seed is dispensed with. This may be vital
importance in bad seasons when the flowers open late and cannot get
through the usual life processes before winter arrives.
Several
cases of vivipary occur among alpine plants. We have already come across
it in the Drooping Mountain Saxifrage and shall find that several grasses
have also adopted this short cut to reproduction.
It must
be remembered, however, that continued vegetative reproduction unsupported
by the formation of ordinary seed lead to the gradual weakening and
undermining of the race, and as we have seen, in the case of the Drooping
Saxifrage, to it eventual extinction.
Dwarf Juniper (Juniperus nana)
This is
quite a common plant in the mountain pastures and is probably only a
starved mountain variety of the Common Juniper which will be described in
Chapter XI.
It is a
very low shrub which has adopted as espalier growth and lies back against
the soil. In fact, it is often almost a carpet plant. In all other
respects, it is quite similar to the common Juniper.
In lowly
growth is, of course, an adaptation to climatic conditions, affording the
plant protection against strong winds and the weight of snow in winter.
LEGUMINOUS PLANTS
We have,
in the grassy areas of the mountain pastures of the Scottish Highlands,
three representatives of the Pea Family. They are the Alpine Milk Vetch (Astragalus
alpina),
the
Yellow Oxytropis (Oxytropis campestris) and the Purple Oxytropis (Oxytropis
Uranensis). The first two are rare plants, the former confined to the
mountains of Perthshire and the neighbourhoods of Braemar and Clova,
whilst the latter is only known in the Clova Mountains. The third plant
is rather more frequent, being often found at quite low levels, especially
near the sea. It is usually found on grassy mountain sides, growing on
stony patches and in rock crevices as well as among the short herbage.
Alpine Milk Vetch (Astragalus alpines)
This
small plant, with a creeping stem which may attain one foot in length, is
usually branched near the base. The branches give rise to several leaf
stalks which support compound leaves consisting of eight to twelve small,
oblong leaflets, with an odd one at the top of the stem. They are
slightly silky. From the axils of the leaf stalks arise long flower
stalks which are terminated by snort, close racems of bluish-purple or
white, tipped with purple flowers.
The
structure and pollination of these flowers will be found fully described
under the Broom (see Chap. XIV). In that same chapter, I shall deal with
the phenomenon of symbiosis in Leguminous plants.
It is
very rare and only those who know its actual flowering stations have much
hope of finding it.
Yellow Oxytropis (Oxytropis campestris)
This
plant is one of those very rare and very local mountain plants which, like
Lychnis alpina, elect to flower in one solitary spot in the
Highlands. Why this should be is a mystery, as there are many other
places equally suitable for its growth.
It is a
perennial with a short, tufted rootstock. The lower part of the stem is
covered with the old stipules and leafstalks of other seasons, which help
to protect the stock against frost and damp. The leaves and flower stalks
arise from the extremity of the stock. The leaves consists of ten to
fifteen pairs of small ovate leaflets with an odd one at the tip of the
main rib, and are hairy, especially on the lower surface, the stomata thus
being protected against excess transpiration. The flower stalks are
rather long and are terminated by a short spike of pale, yellow flowers
which are sometimes tinged with purple, especially in the lower part.
They possess a short, hairy clayx which protects the flowers admirably
whilst in bud.
After
flowering the Yellow Oxytropis produces short, swollen oval pods which are
produced to a fine point, and are covered with thick, black hairs which
protect the sees from rain and amp.
Purple Oxytropis (Oxytropis Uranensis)
This
plant is much more common than the other two Leguminous plants already
described, being frequently found on grassy mountain sides and sometimes
descending to sea-level near the sea.
It is
similar in habit to the Yellow Oxytropis, but is densely covered with
soft, silky hairs, and is hense much better protected against drought.
The flowers are a bright purple.
THE
POTENTILLAS
The next
group of plants, which is to be found in the drier areas of the grassy
mountain pastures, includes three plants of rather similar habit. The
first, the Tormentil (P. erecta), is an abundant plant in the lower
part of the pastures; it is, of course, a very common lowland plant. The
second, the Mountain Potenilla (P. alpestris), is a much less
common plant which is found here and there, especially in the southern
Highlands. The third, the Sibbaldia (P. Sibbaldia), is very common
in the higher pastures, often covering large tracts of the mountain sides.
Tormentil (Potentilla erecta)
This very
abundant plant is too well known to require a close description, but it is
cleverly adapted to dry situations.
It has a
thick, woody, perennial stock which is well able to defy the cold and damp
of winter, and from it arise several long, branched stems which may be
erect or procumbent at the base. They climb over surrounding vegetation
until, when they are clear of obstructions, the flowers are formed. They
are clothed with many leaves, the lower ones of which are stalked and
consist of five ovate, coarsely toothed leaflets which radiate like the
fingers of the hand. The upper leaves which are most exposed to the sun
and wind are reduced in size to limit transpiration. This plant is again
more or less silkily hairy.
The
flower stalks arise in the axils of the leaves and are terminated by
several small, bright yellow flowers, which usually have only four
petals. If we examine the flower, we shall find that in the centre is a
conical receptacle on which is situated a large number of one-seeded
carpels. Around this central disc are situated the nectaries, and around
them a circle of many stamens whose anthers face outwards. An insect
usually alights upon the centre of the flower and naturally leaves
transported pollen upon the stigmas, but on turning around to lick the
nectar ring it becomes dusted with pollen from the anthers. As they face
outwards and away from the stigmas the danger from self-fertilization is
small. The flowers set an abundance of small, light seeds which are blown
to a considerable distance by the wind.
Small
bees, flies and hover-flies are the chief visitors. A plant so well
adapted to conditions and setting an abundance of cross-fertilized seed is
well on the road to success. This explains why this plant is so common in
the lowlands as well as in the mountain pastures.
Mountain Potentilla (Potentilla alpestris)
This
plant is rather similar to the preceding. By some botanists, it is
supposed to be a distinct species, while others think that it is a variety
of the lowland plant, the Spring Potentilla. (P.verna).
As in the
case of the Tormentil, it has a perennial stock from which arises an erect
stem which may be eight inches in length. The lower part is clothed with
long, stalked leaves which consist of five to seven large, ovate, toothed
leaflets. The upper leaves are smaller, with short stalks and with five
or only three leaflets. They are covered with silky hairs which are
sometimes so abundant as to give the leaves a grayish appearance. The
flowers in this species are large, and of a bright, golden yellow, with
five petals, sometimes spotted with pink or white. They are much more
conspicuous than in the case of the lowland species. This is, of course,
related to the fewer insects such as bees in the higher area.
Scottish Sibbaldia (Potentilla Sibbaldia)
This is a
rather different plant from the foregoing. The perennial stock forms a
very dense, spreading tuft, clothed with small leaves consisting of three
wedge-shaped leaflets which are green, but hairy on both surfaces. The
tuft passes the rigours of winter beneath the snow whose weight its
structure is well able to support. The low growth and small hairy leaves
are, of course, adaptations against drought which may be very severe in
its exposed habitat. The tufts give rise to short, naked, flowering stems
which are terminated by small, greenish inconspicuous glowers, possessing
five very small yellow petals. The green calyces are the most conspicuous
part of the flower.
The
flowers do not produce nectar and, although they may be visited by small
flies, are probably self-fertilized.
 THE
LADY MANTLES
The most
frequent Lady’s Mantle to be found in the mountain pastures is the Alpine
Lady’s Mantle (Alchemilla alpina). It is sometimes very abundant,
forming large colonies, and can be met with at over 4,000 feet.
The
perennial stock sends out creeping runner with root at the nodes. The
flowering stems are usually creeping and attain six inches or more in
length. This stock is crowded with long, stalked radical leaves which are
divided to the base to form five or seven oblong segments or leaflets. To
guard against excess transpiration the stems and leaves are covered with
beautiful, shining, silver hairs.
The
flowering stems are terminated by spikes of small greenish flowers in
which there are no petals, the double calyx taking their place.
Another
alpine Lady’s Mantle is Alchemilla aseptic, which is much less
common but frequents similar places to A. alpina and may also be
found at over 4,000 feet. It is easily distinguished from the former by
its large, kidney-shaped leaves which are quite undivided. Its small,
yellowish-green flowers are produced in clusters at the summits of the
stems.
The
Common Lady’s Mantle (A. vulgaris) a frequent plant n the lower
pastures, has several varieties which reach 4,000 feet in the Highlands.
They are similar to A. alpestris
with
leaves of the same form, but they are covered with soft, downy hairs on
one or both surfaces. A further distinguishing character is the hairs on
the stems which spread outwards in A. Vulgaris, but lie flat in
A. alpestris.
Heart-laved Twayblade (Listera cordata)
This tiny
plant belongs to the aristocratic Orchid Family. This must come as
rather a surprise to my readers, for there is nothing very conspicuous or
unusual in the tiny spikes of brownish-green flowers.
One must
search for it carefully in the higher mountain pastures, for although I
have found it at only 900 feet in Lochaber, I have found extensive
colonies in the grassy hollows of the Cairngorms at nearly 3,000 feet,
nestling so deeply into the mosses and alpine herbage that they were only
discernible with difficulty.
The roots
of this plant consist of a mass of thin fibres and are not tuberous as in
most of our native orchids. From the stock arises a single, slender stem
to about six inches in height. About two inches up this stem are produced
two broad, opposite leaves which are never more than one inch in length
and are heart-shaped at the base. These are the only leaves that are
produced. The stem is terminated by a short raceme of very small flowers,
the upper petals and sepals of which are spreading, but the lip is long
and very narrow, cleft into two at the extremity and bearing two tiny
teeth at its base. I shall deal with the pollination of this orchid in a
later chapter.
GRASSES AND GRASS-LIKE PLANTS OF THE MOUNTAIN PASTURES
The
species of grasses making up the actual mountain pastures depend largely
on the soil and its water content. Where drainage is poor and the soil is
acid-peat with stagnant water, as occurs on large areas of the more gentle
mountain sides, then the grasslands are dominated by the Mat-grass (Nardus
stricta), which, as we have already seen, penetrates even into the
alpine zone.
Its
creeping rhizomes are almost on the level of the soil and the vast number
of individual plants dispute every inch of soil They creep over each
other, and as the under plants are smothered so a deep mass of dead
rhizomes and roots is formed. The thick, mat-like colony invades all the
surrounding pasture, until large area are under its sway. It is admirably
suited to its habitat as the thin, wiry leaves are little sough after by
grazing animals. Its roots contain a fungus which breaks down the peat
and humus and makes it available to the plant. Its huge colonies are
almost impenetrable to other species.
A
well-established Nardus grassland, however, usually furnishes a
habitat for one or two other grasses. Thus the Wavy Hair-grass (Deschampsia
flexuosa) is often found in the dense mats, its shallow roots finding
sustenance in the soil which collects around the tussocky Nardus.
This plant we have already met in the alpine pastures, so a further
description is unnecessary.
Certain
species of Agrostis, the Bent-grass, also grow in these areas, the
most common being Agrostis canina, a densely-tufted grass with
narrow, flat leaves. It also forms colonies by means of long runners.
Agrostis stolonifera, a similar species with rather wider leaves, and
A. tenuis, with difficulty distinguished from the latter, may both
be found with Nardus. They are characterized by their flowering
stems whose dry, stiff, erect remains are in evidence long after the
flowers have withered and the seeds have been distributed.
Where the
slope is greater and running clear water is in evidence, the Nardus
grassland gives way to that dominated by the Blue Moor-grass (Molinia
vaerulea). This also forms pure grasslands of great extent to the
exclusion of other species. It has a short rhizome giving rise to large
tufts of long, flat still leaves. The flowering stems bear two sets of
similar leaves, separated by a basal internode which acts as a food
store. The leaves are deciduous and drop off the plant in the autumn.
They, of course, form a dense humus which in time composes a soil dry
enough for other grasses to penetrate.
A
frequent colonist in this type of grassland is Deschampsia caespitosa,
which also forms dense tussocks of long, flat leaves whose rough edges cut
like knives if handled carelessly. It produces an elegant panicle with
many slender, spreading branches covered in silver-grey or purplish
two-flowered spike lets.
Another abundant grass-like plant in these areas is the Deer-grass (Scirpus
caespitosa).
This is
actually not a grass at all as it belongs to the Sedge Family (Cyeraceae).
It is also a densely tufted plant giving rise to a large number of erect,
green structures which might be mistaken for leaves, but are actually
steams. The leaves are reduced to short, brownish sheaths at the base of
each stem. The stems contain chlorophyll and carry on the photosynthetic
functions of the plant. Each stem is terminated by a tiny, ovoid, brown
spike of flowers.
A number
of read Sedges (Carex) are also found with Molinia, the
chief species being C. dioica, C. flava, C. panicea, C. Goodenowii
and C. stellulata.
Where
much stagnant water occurs, the Cotton Grass (see chap. XV) often
supplants Molinia.
Other
grasses of the mountain pastures are the Sweet Vernal-grass (Anthoxanhum
odoratum) already described in the alpine section. Sieglingia
decumbens is another common grass of tufted habit. It is usually from
six inches in height and its narrow nleaves have a few, long, soft, white
hairs on their sheaths and edges. It produces a small raceme of only five
or six spike lets, each of which contains three or four flowers.
The
Meadow-grass (Poa pratensis) is often present and it establishes
itself by means of a creeping underground rhizome and overground runners.
It thus colonizes large territories in a short period. It produces a
large panicle of slender, spreading branches covered with numerous small,
green spike lets. The Annual Meadow-grass (P. annua), so common
everywhere, is also found in the mountain pastures.
The
Fescue-grasses (Festuca) are often present and F. ovina is
often abundant, covering large amounts of land. Its variety F. alpina
was dealt with n the alpine section. It closely resembles it, but
does not form viviparous spike lets. The Red Fiscue (F. rubra), a
taller species with flat leaves and a reddish-panicle, is also widespread.
One
other grass-like member of the mountain pastures is the Heath Rush (Juncus
squarrosus),often found with Nardus. It is a tufted plant with
several stout, erect stems about one foot in height. The radical leaves
are very narrow and deeply grooved with the stomata on the inner surface
of the groove. The stems are terminated by a panicle of glossy brown
flowers. |
