When a tree is old,the tubes in the centre of the tree don't carry water.The walls of the tubes have become thick with materials which have stuck along them over the years,forming a kind of wood called“heartwood”.This kind of wood is darker in color than the young,growing wood on the outside of the tree.
You don't very often see whole tree trunks which have been cut across.But once you learn to read a cross section of the wood,you can see much more in wood which has been used to make boxes,houses and other things.
In most wood,instead of seeing the trunk cut across,you are seeing it cut along its length.Because you don't see the whole tree,you can't tell how old it is.
Title:__20__of a Tree
General information Old trees
Items Facts Items Facts
Where can rings be seen On the __21__of a trunk The tubes in the centre of the tree Don't carry water
The__22__of rings Helps us know about its age The walls of the tubes Become
__23__;
Form __24__
__25__lightcolored rings Show the tree grows quickly
Narrow__26__
rings Mean the tree grows slowly
Microscopic tubes Function Carry__27__
Features Wide and __28__when growing quickly
Narrow and stuck together when growing __29__
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