Protection of plants. Adverse temperature conditions and a water lack

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In summer not too dry and hot day the grassy plant feels well and quickly enough grows. Other business if it suddenly to transfer in the summer somewhere to hot desert or in the winter highly in mountains; here it without special protection long has not survived. In both cases he should test on itself action of the extreme temperatures aggravated in desert with absence of water, and in mountains - its inaccessibility owing to freezing. Nevertheless both in mountains, and local plants live in deserts and even keep ability to growth. How it is possible to them? The answer to this question will allow us to make to itself representation about refinement and about a variety of the mechanisms which have arisen in the course of evolution under the influence of natural selection.

Plants can provide to themselves a survival in a severe climate in three main ways: 1) by means of mechanisms which give the chance to them to avoid adverse influences; 2) by means of special structural adaptations; 3) thanks to the physiological properties allowing them to overcome fatal influence of environment. avoid adverse conditions of a plant can, having spent this time in the form of steady seeds or at rest. In a hot and dry season the desert seems absolutely fruitless, but after spring rains here the various grassy plants which seeds lay before in sand at rest quickly are born. At once after germination these plants start to grow quickly, blossom and, having provided kind preservation, i.e. Having formed new steady seeds, die off to the beginning of dry and hot summer. In similar image behave and odnoletniki in moderate zones: They finish the life cycle in favorable summer days, and winter in the form of steady seeds. Grassy perennial plants can winter in the form of underground reserving bodies - bulbs or the rhizomes protected from vymerzanija by a layer of earth, and over it is frequent also a snow layer. Certainly, tree species of moderate zones cannot take cover from a frost in soil as it do grassy mnogoletniki, but also they are somehow protected from winter colds: their gentle leaves fall down, and to winter there are only branches steadier against a cold and covered rigid cheshuevidnymi kidney leaves. In the same way of a plant can resist and to water deficiency. At bush Fouquieria growing in desert splendens leaves remain only during a season of rains; during the dry period they are dumped, because at weak water inflow from soil its evaporation from their extensive surface would threaten plant existence.