Plants In Extreme Conditions In many ways, plants are far more versatile and successful to life on earth than animals and have been here for far longer. They were the first to colonise this planet and without them we would not exist, for we are totally dependent on them. Even today with all our technology they continue to amaze us with their ability to inhabit places we humans could not survive, from the frozen Antarctic to the intensity of a volcanic spring, plants utilise their environments to their own advantage and evolve to survive the harshest of landscapes. A plant needs four basic things to survive, water, warmth, light and minerals and any place that can provide even a little of these essential needs, will be colonised by plants. The most important environmental factors to which plants must adapt themselves to are, water availability, temperature change, light, and soil conditions.For any species, each of these factors has a small or large value, and species that have adapted to extreme environments have undergone changes to adapt to their particular and often narrow ecological conditions.
Its survival of the fittest and the plants that I shall discuss first in this essay, respond to their environment so well that they can live in a part of the world that denies them almost all of their four basic needs, the Antarctic. The immense Antarctic ice-cap holds three-quarters of the worlds freshwater, this may seem ideal as plants need water, but plants can only use water in liquid form, and the frozen surfaces of the South Pole are inaccessible to them. Light is also a hard commodity to find here as the sun, even in summer never rises high in the sky, and in the autumn it sinks until it leaves the South Pole in darkness for half the year and as for warmth, it is the coldest place on earth. Yet three hundred miles from this place were no living thing could survive for any length of time, there are plants, algae, living together with fungi on the tips of mountains, which protrude through the snow. These hardy plants are mostly in a dormant state, the severe temperatures rising only a couple of days a year just enough to enable the Lichen to enliven their body chemistry and to photosynthesise.Some Lichen is black and this enables them to retain what little of the suns heat they can to melt the snow around them. Some grow on rocks that are frequented by birds as their droppings provide a rich source of nutrients. This activity however happens in the warmest part of the summer and as cold winter sets in they return to their dormant sleep.
Other algae manages to survive in the snow itself, they live in between the individual flakes just below the surface and during the summer their chlorophyll is disguised with a red pigment to protect the algae from the ultra-violet rays of the sun, as they shine more strongly through the snow. As the sun shines however, it melts the snow and does give them the liquid water they need.In the winter, when the snow is below zero the algae manufacture a kind of anti-freeze which prevents their bodies from freezing and they are invisible below the surface, but when the summer arrives once more they launch themselves forward with microscopic beating hairs and move closer to the surface and the light. At the other end of the earth, The North Pole, the situation is different. After the Ice Age, as the ice retreated, plants began to colonise the land it revealed and as they did they evolved in to different forms, better equipped to grow in their new environment. A species of willow developed that grows not vertically but horizontally, restricted to the ground, less the fierce Arctic wind should level it. It may become as long as a European relative would grow high, but it never raises more than four inches of the ground.In the Arctic summer, the plants that live there have a moderate supply of the four requirements.
The temperature is well above freezing, so there is plenty of water around and the sun is high in the sky for weeks. The one thing they are short of however is minerals, as rocks shattered by frost in the harsh winter and ground down to a unrefined sand are unsuitable to be absorbed by the plants. The richest source of nutrients to be found are the dead decomposing bodies of the animals who live here, and the largest of these animals, the musk ox provides an excellent start in life for the seeds which are blown into its huge dome of a skull and they thrive in the soil surrounding the corpse which is enriched with nutrients. Plants who live on top mountains can find that they have not only to endure the freezing nightly temperatures but also the blazing daytime sun.On Mount Kenya plants have to survive these conditions daily as the weather alternates between winter and summer every twenty-four hours. One type of lobelia has risen to the challenge and developed an ingenious way of dealing with its predicament.
Its centre forms a watertight cup that holds three quarters of a gallon of liquid, which each night freezes, on the surface, the water underneath stays liquid and therefore prevents any damage to the bud which is immersed within it. The plant now faces a second hazard, the heat of the sun evaporating the liquid, which would leave the lobelia defenceless at night. However the liquid is not rainwater but a substance secreted from a special gland and it contains a slime, which hinders evaporation. Preservation against evaporation is also of vital importance to the plants that live in deserts.
In The Namib Desert in Africa, one of the harshest deserts in the world, every drop of moisture has to be stored and used to the fullest, and the plants who live in this dry unrelenting heat have come up with many unconventional ways of scrimping and saving what little they have. One of the stranger methods of storing water belongs to the quiver tree, like the others belonging to the species it grows thick succulent leaves that grow high of the ground. This itse …