Vascular  tissue  system:
   xylem.
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   The  tracheids  and vessel elements are dead, hollow cells specialized
   to conduct water from the root.
<P>
   Tracheids  have  tapered  ends  with  pits, while vessel elements have
   perforated ends to allow water transport.
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   The  secondary  walls  of  tracheids  also  contain  lignin to provide
   support.