It is often possible to recognize a tree by its bark, whose aspect can however strongly vary according to the areas (latitudes, altitudes), its age, its exposure, and the possible presence of Lichen S or others épiphyte S.
DefinitionsIn the current language;
on calls bark the external fabrics, died, crevassés, which sometimes exfoliating by plates, and that the botanists call “ rhytidome ”.
l' bark includes/understands the whole of the fabrics known as cortical products towards the outside of the Tige by the operation of the Cambium, on the branches, the trunk, but also the root S of the trees. It is a layer of cells generating, also called wood-and-bast base, which produces towards the interior the Xylème, or wood, and towards outside the Phloème or liber. At the Angiosperme S, outside the phloem, a second sitted generator, the subero-phellodermic cambium or cortical cambium produces towards the interior the Phelloderme, which is the alive bark, and towards outside a fabric suberous impermeable, the cork. The phelloderm ensures the continuity of external protection, in spite of the increase in diameter in stem. the bark of the trees is often rich in bitter toxins (phenols) and principles (tannins) what makes it more protective, but also a source of medicinal principles makes of it, which certain animals also learned how to exploit (ex: the Aspirine of the bark of Willow S grazed by animals).
Wounds of the barkThey are frequent, of natural or human origins. The production of bark takes part in the cicatrization of the tree, being accompanied by a production by phenols, resins and other molecules limiting the infection by mushrooms and bacteria.
UseThe bark of unquestionable plants is exploited by the man at various ends:
- the bark of the Chêne-liège produces cork;
- the bark of the grooves is used like spice;
- the unrolled bark of the Bouleau to boat ( Betula will papyrifera ) was used by the Indians of the Canada to make the envelope of their boats; The Birch is also used in Northern Europe like under-roof under the lumps of earth enherbées of traditional houses with vegetable Toiture.
- of the bark of the Quinquina one extracts the Quinine and quinidine;
- of the bark of the white Willow, one extracts the Aspirine;
- the bark of the Tilleul produces by Teillage textile fibers;
- the bark of the Mûrier to paper ( Broussonetia will papyrifera ) was used to manufacture paper just as that of the Lokta ( Daphne papyracea ) always used in an artisanal way to the Nepal;
- the residual barks of the factories of sawings are used to produce energy and panels of wood
Certain trees and shrubs are cultivated because of the decorative aspect of their bark.
In Horticulture, one often uses barks of pine to carry out insulating Paillis.
the Earth's crust , or “earth's crust”, indicating the surface part of the Globe.
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