Wood - Wood:Secondaryxylem

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Wood: Secondary xylem The structure of wood varies from species to species and between major groups. A common  categorization separates the  softwoods  of gymnosperms from the  hardwoods  produced by  angiosperms. (These are not very good descriptive terms because of the great variability in density  among species in both groups, but the groups do differ in the kinds of cells in their wood.)  Gymnosperm wood . Softwood lacks vessels and is composed almost entirely of tracheids. The  rays are ribbon-like structures of parenchyma, one cell wide and only a few cells deep. Vertical  resin  ducts  or canals are characteristic of gymnosperms. The ducts intercellular spaces lined with  parenchyma tissue, the cells of which secrete resin into the cavity in response to wounding.  Angiosperm wood . Hardwoods are harder than most softwoods because of the numerous fibers 
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This note was uploaded on 11/14/2011 for the course BIO 1421 taught by Professor Farr during the Fall '08 term at Texas State.

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