One can buy heartwood from a wood shop or woodcutter's yard.
Heartwood is the dense inner part of a tree trunk and it is this
section that is mostly used for the hardest timber.
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The heartwood of a tree doesn't actually do anything. It is
center of a tree. It i
s non-functioning, darker wood and sometimes dead.
Heartwood supplies the flexibility to allow the tree to sway in
the wind.
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When the juvenile wood get older and loses its functions it
becomes heartwood.