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bark,outer covering of the stem of woody plants, composed of waterproof cork cells protecting a layer of food-conducting tissue—the phloem or inner bark (also called bast). As the woody stem increases in size (see cambiumcambium
, thin layer of generative tissue lying between the bark and the wood of a stem, most active in woody plants. The cambium produces new layers of phloem on the outside and of xylem (wood) on the inside, thus increasing the diameter of the stem.
..... Click the link for more information. ), the outer bark of inelastic dead cork cells gives way in patterns characteristic of the species: it may split to form grooves; shred, as in the cedar; or peel off, as in the sycamore or the shagbark hickory. A layer of reproductive cells called the cork cambium produces new cork cells to replace or reinforce the old. The cork of commerce is the carefully harvested outer bark of the cork oak (Quercus suber), a native of S Europe. The phloem (see stemstem,
supporting structure of a plant, serving also to conduct and to store food materials. The stems of herbaceous and of woody plants differ: those of herbaceous plants are usually green and pliant and are covered by a thin epidermis instead of by the bark of woody plants.
..... Click the link for more information. ) conducts sap downward from the leaves to be used for storage and to nourish other plant parts. "Girdling" a tree, i.e., cutting through the phloem tubes, results in starvation of the roots and, ultimately, death of the tree; trees are sometimes girdled by animals that eat bark. The fiber cells that strengthen and protect the phloem ducts are a source of such textile fibers as hemp, flax, and jute; various barks supply tannin, cork (see cork oakcork oak,
name for an evergreen species of the oak genus (Quercus) of the family Fagaceae (beech family). The cork oak (Q. suber) is native to the Mediterranean region, where most of the world's commercial supply of cork is obtained.
..... Click the link for more information. ), dyes, flavorings (e.g., cinnamon), and drugs (e.g., quinine). The outer bark of the paper birch was used by Native Americans to make baskets and canoes.
barque(both: bärk), sailing vessel with three masts, of which the mainmast and the foremast are square-rigged while the mizzenmast is fore-and-aft-rigged. Although the word was once used to mean any small boat, later barks were sometimes quite large (up to 6,000 tons). In addition to the standard three-masted bark there are also four-masted barks (fore-and-aft-rigged on the aftermast) and barkentines, or three-masted vessels with the foremast square-rigged and the other masts fore-and-aft-rigged. Large numbers of barks were employed in carrying wheat from Australia to England before World War I; and in 1926 the bark Beatrice sailed from Fremantle, Western Australia, to London in 86 days.
The tissues external to the cambium in a stem or root.
The decarburized layer formed beneath the scale on the surface of steel heated in air.
A three-masted sailing ship whose foremast and mainmast are square-rigged and whose mizzenmast is fore-and-aft-rigged.
The protective outer layer of a tree, composed of inner, conductive cells and outer corklike tissue.
1. a protective layer of dead corky cells on the outside of the stems of woody plants
2. an informal name for cinchona