MadSci Network: Botany

Re: Can Half the tree be alive and half be dead?

Date: Wed May 8 19:45:29 2002
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 1020872835.Bt

Actually, it is normal for half or more of an older tree to be dead because the 
wood (xylem) is composed mainly of dead, hollow cells that transport water up 
the tree. These dead, hollow cells are of two main types, tracheids and vessel 
elements. Most of the tree trunk is wood. The outer layer, or bark, contains 
living phloem cells that transport minerals and organic compounds. However, the 
outer bark cells, termed cork cells, are dead at maturity. The main living, 
dividing layer in the tree trunk and roots is just beneath the bark. It is 
termed the vascular cambium. The bark also contains a cork cambium, a dividing 
layer which produces new cork cells.

Many old trees are partly or completely hollow because the old wood has rotted 
away, yet the tree is still alive and is often structurally sound. 



Plant tissue types


Inside a Tree Trunk: The Bark

Liberty Tree (a hollow tree)

National Arbor Day Foundation

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