The hard, central core of a tree trunk (the heartwood) that no longer carries sap and provides structural support.
From Latin 'durus' (hard) plus '-amen' (nature or quality of). A botanical term coined to describe the inactive inner wood as opposed to the living sapwood.
Trees are like onions with layers—the outer sapwood carries water, but the inner duramen is dead and just provides strength, which is why old heartwood is perfect for building!
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