For other meanings of bark, see Bark (disambiguation).
Bark is the outermost layer of stems and roots of woody plants such as trees. It overlays the wood and consists of three layers: the cork , the phloem, and the vascular cambium - in other words, most of the stem except for the xylem. (This division may seem arbitrary, but the easiest way to split a stem parallel to its length is by pulling the bark away from the xylem.)
The vascular cambium is the only part of a woody stem where cell division occurs. It contains undifferentiated cells that divide rapidly to produce secondary xylem to the inside and secondary phloem to the outside.
Along with the xylem, the phloem is one of the two tissues inside a plant that are involved with fluid transport. Phloem's specific job is the transport of organic molecules - particularly sugars - to wherever they are needed.
Cork, sometimes confused with bark in colloquial speech, is the outermost layer of a woody stem, derived from the cork cambium. It serves as protection against damage, parasites and diseases, as well as dehydration and extreme temperatures. Cork can contain antiseptics like tannins. Some cork is substantially thicker, providing further insulation and giving the bark a characteristic structure, in some cases thick enough to be harvestable as cork product without killing the tree.
Among the commercial products made from bark are cork, cinnamonCinnamon Cinnamomum zeylanicum is a small evergreen tree 10-15 m tall, belonging to the family Lauraceae, and a spice obtained from the inner bark of this species. It is native to Sri Lanka. The leaves are ovate-oblong in shape, 7-18 cm long. The flowers,, quinineQuinine CHNO, is a natural alkaloid having antipyretic, antimalarial and analgesic properties. It was formerly used in the prevention of malaria until supplanted by its derivatives quinacrine, chloroquine, and primaquine. Quinine may still be used to trea (from the bark of CinchonaCinchona is the name of a genus in Rubiaceae family, large evergreens that can grow over 10 metres tall. There are over 40 species in the genus, many of which have spread from their South American center of origin to countries all over the world (especial) and aspirinAspirin or acetylsalicylic acid is a drug in the family of salicylates, often used as an analgesic (against minor pains and aches), antipyretic (against fever), and anti- inflammatory. It has also an anticoagulant (blood thinning) effect and is used in lo (from the bark of willowAbout 350, including: Salix alba White Willow Salix amygdaloides Peachleaf Willow Salix arbuscula Mountain Willow Salix aurita Eared Willow Salix babylonica Peking Willow Salix caprea Goat Willow Salix caroliniana Coastal Plain Willow Salix cinerea Grey S trees).
- See also : Bark painting , Bark beetle
