secondarygrowth213-page6

secondarygrowth213-page6 - Conifer wood contains only...

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Secondary Growth in Stems: Wood, Bark and Surface Features - 6 In general, wood is comprised of: Xylem vessels and/or tracheids Fibers Ray parenchyma, which is responsible for lateral conduction of water. Eudicot Wood Eudicot wood is comprised of vessels, some tracheids, fiber and parenchyma rays. The organization of xylem tissue in wood will be discussed a bit later when we look at wood patterns and orientation of wood, features that most humans have, on occasion, observed. Conifer Wood Much of the wood used commercially is from conifers. Conifers are often called softwood, while the wood of flowering plants (eudicots) is known as hardwood. These designations have no meaning for the strength of wood.
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Unformatted text preview: Conifer wood contains only tracheids, no vessels and minimal parenchyma, so conifer wood appears more uniform than the wood of flowering plants that have larger diameter vessels, along with the numerous fibers. Conifer tracheids are characterized by prominent bordered pits along their walls. Microscopically, the bordered pits of tracheids are spectacular. In addition, resin ducts (or canals) are present in conifers. A resin canal is lined by a ring of parenchyma cells. Resin is believed to be a defense mechanism that helps protect the plant from predator damage. Pine: two-year cross section...
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This note was uploaded on 01/08/2012 for the course BIO 213 taught by Professor Makina during the Fall '09 term at SUNY Stony Brook.

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