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By an alpine plant we mean one whose structure and
adaptations allow it to grow in the Arctic conditions which appertain on
high mountain sides and summits.
In this book I am restricting the term to those plants
which are always to be found above 3,000 feet. They may be found below
this level, but as a general rule are most abundant above it. Generally
speaking, the highest mountains are richest in alpines, although they are
mostly found considerably below the summit. They possess very specialized
adaptations to combat the climatic conditions of these high regions, and
we shall discuss these adaptations fully when the various species are
described.
Plants which live on the high summits and wind-swept
mountain sides, have at to face severe climatic conditions. They are,
therefore, greatly modified to combat the combined effects of cold, heat,
dampness, and aridity, strong winds and sunshine.
In these wild regions the soil is covered by a deep
mantle of snow for many months. Throughout the long winter, streams are
frozen solid and violent storms fill the depressions and corries with huge
masses of snow. It may be as late as June before the higher summits are
free of snow, whilst N.E. corries and slopes may never be clear at all.
By October the snow have usually recommenced and sharp frosts occur well
before this date. In the short season, June to late September, the plant
must produce leaves and flowering stems, its flowers must be pollinated,
its seeds must be ripened and these must be distributed.
The soil is often frozen from October to mid-May and
this means that plant life is impossible as the roots are unable to absorb
water. Later on, the day temperatures become much higher and in sunny
places the soil temperature may reach 100 degrees F. The night
temperatures, however, are below freezing point well into June so that for
long periods the soil is frozen at night. These large daily extremes of
temperature are very trying to plant life, causing a very irregular supply
of water to the leaves and stems and a consequent derangement of
transpiration. For this reason, alpine plants have evolved special
devices to control transpiration and consequent loss of water.
Water supply is the greatest influence on life in high
mountains regions. Owing to low soil temperature the water in the soil is
often not available as the roots are only able to absorb small quantities
and hence a state of physiological drought exists.
Although much rain and snow falls on the Scottish
mountains much is lost through the running off of water from steep slopes;
the stony soil is able to absorb little water and owing to its porous
nature holds very little. Alpine soils are hence dry, water collecting in
the hollows only, and in these places small tarns and bogs occur.
Again, the sun raises the soil temperature to 100-120
degrees F. during the summer, and this makes for very rapid evaporation
from the surface layers of the soil.
The fierce winds which seep the high plateaux and
mountain sides also cause rapid evaporation and contribute to the dryness
of high mountain soils. The lower atmosphereic pressure on the mountain
tops also increases the evaporation rate.
Other factors influencing plant life in the alpine
regions are the intensity of sunlight, rarity of the atmosphere, and its
clearness, but these effects are much more obscure than those of the other
influences.
In order to combat such conditions alpine plants are
highly specialized. They are thus almost all perennials, possessing an
underground stem or rhizome in which food substances are stored during the
summer. They pass the winter in a dormant state, their upper stems and
leaves dying down. When spring arrives, the plant can commence growth
immediately, using its stored foods until such time as the roots can
absorb water and nutrient salts from the soil.
To combat drought most alpines have a low, bushy habit;
their leaves are usually very small and often have thick, hairy coats,
coatings of wax, or a thick leathery epidermis; the root system is usually
very well developed and in many cases the underground portion is much
larger than the aerial portion of the plant. It is thus obvious that
trees cannot exist at all in this zone and that tall herbaceous plants
will be rare.
Enough has been said, however, about the adaptations of
alpine plants to their surroundings. Most of the points of this chapter
will be enlarged upon in the ensuing pages where many types of alpine
plant architecture and specialization will be dealt with.
In spite of adverse conditions many species of plants
find existence a success on the high mountains. Wherever a pocket of soil
occurs and along the sides of springs and rivulets, the competition
between different species and also between members of the same species is
very severe and the struggle to survive becomes merciless. Only the
fittest can hope to carry on under these conditions and it will be seen
how well suited to the struggle are our native alpine and mountain plants.
Whilst not as abundant and as numerous as the species
to be found in Alpine Switzerland, the flowers of our Scottish mountains
are by no means lacking in interest and variety. Actually, they are more
nearly related to the flora of the Scandinavian Peninsula, although many
species are also found in the Alps.
The haunts of these alpine plants are wild and
inspiring. The black corries, where precipices rise sheer for a thousand
feet, where broken chimneys and vast heaps of scree encumber the climber
and where the snows lie late, it is here that many a rare alpine has its
home. In these romantic regions where wild cascades plunge into space in
clouds of spray, where the falcon nests and the eagle often has his eyrie,
we may find the Alpine Aster, the Snow Gentian or the Alpine
Forget-me-not. The cushions of broken granite, the mossy ledges where
streams trickle gently over the polished stones, these are the places
beloved by many a rare alpine plant. Not for them the gently curving
mountain side. They live in scenes of grandeur and beauty which add to
their charms. Where the eye roves over half of Scotland, across black
pine forests and purple moorlands, across wild rivers and sparkling loch,
across proud mountain tops to the far, blue sea, the lover and collector
of our native alpines will be among his treasures. He can study nature
amid magnificent and inspiring surroundings which will lift his thoughts
high above the level of ordinary things, in the mountains we are nearer
God than in any other place.
Naturally many alpine plants can be found without the
trouble and exertion of climbing into the corries. On the more gentle and
easier slopes we may find plants as the Trailing Azalea, the Alpine
Bear-berry and the Creeping Willow which delight in dry rocky places. The
beautiful green springs where bog mosses, and alpine grasses form
delightful oases amid the rocks, are the haunts of many lovely little
plants; the Alpine Willow-herb, the Alpine Willow-herb, the Alpine
Stitchwort and the Starry Saxifrage grown here in profusion.
Let us now commence our acquaintance--or perhaps
recommence it--with the many beautiful plants to be found on our
mountains. For the purpose of this book I have divided the Alpine Flora
into four sections. Two of these, the Cushion Plants and the Carpet
Plants, illustrated outstanding types of alpine plant architecture. The
third is confined to the Alpine Saxifrages, whilst the fourth section
deals with other types of plants to be found in the alpine zone. |
