Wednesday, March 25, 2009

Bark is a Protective Covering


Bark is the hard protective covering or rind of the trunk, stem, branches, and roots of a tree, as distinguished from the wood. The bark consists of an inner and an outer layer but only the inner layer is alive. Bark is found primarily on older trees.
Very young trees have a thin skin called cork. Cork is composed of layers of dead cells which are saturated with waterproof substances called suberin and tannis. These chemicals are commercially extracted for use in tanning leather. In some ways cork is somewhat like our own skin, which is composed of dead skin saturated with the waterproof protein keratin. Keratin is a tough, fibrous protein that is especially common in skin, claws, hair, feathers and hooves. As with the cork of young trees our skin prevents diseases from entering our bodies.
When the cork layer of a tree becomes thick is called bark. The bark of western cedars can be as much as a foot thick (30cm).
The bark of a tree is full of openings that permit air to pass freely between the outside cells and the living layers of cells beneath. The openings allow the gas exchange through even the thickest tree trunks. The layers of cells underneath the bark grow and die, becoming converted into bark in the process.
Bark is used commercially in the tanning of leather (as mentioned above), in canoe building, and in basket making and in the manufacture of clothing and shoes, food flavoring, medicine, and cork and cork products.
The Native North Americans used birch bark to cover canoes and tepees, which were sturdy, light and easy to transport. The natives of British Columbia made coats and hats from pine bark, and rain wear from elm bark.
The spice known as cinnamon has been cultivated for centuries and is a popular aromatic and flavoring ingredient in foods, soaps, and medicines. A cinnamon farmer typically strips the bark off the stems of a cinnamon tree and collects the calyx from the base of each yellowish-brown cinnamon berry Fragrant cinnamon oil results from distilling the bark and calyx, and cinnamon sticks are made from the tightly rolled and dried bark of the stems.
Common witch hazel belongs to a group of deciduous flowering shrubs that are cultivated for their fragrant, colorful, frost-resistant flowers. Although grown as an ornamental, witch hazel is also valuable for the chemicals that can be extracted from its bark, wood and leaves and used in the manufacture of coagulants, cosmetics, and liniments.
The bark of the American Basswood had many uses. Inner bark fibres were twisted into twine, string or thread and used in mat weaving, bag weaving or with birch bark for building wigwams. The inner bark of the American beech was ground into flour and used in bread making.
The inner and outer bark of many native trees were used as medicine by aboriginal peoples, early settlers and today herbalists include many in their medicinal collections. It should be kept in mind however, that many plants in our region are poisonous or harmful and may cause adverse reactions if consumed or used externally. Trial and error is not the way to find out which will sicken you and which will not.

Speaking of Nature
Jim Ferguson, 5313 River Road, R.R.5, Renfrew, Ontario K7V 3Z8 Phone 613-432-2738 email jamesh@nrtco.net

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