1) Heartwood 2) Wood 1) Heartwood 
heartwood
• (n.) The heartwood of an exogenous tree.
Du·ra'men noun [ Latin , hardness, a hardened, i. e. , ligneous, vine branch, from durare to harden. See Dure .] (Botany) The heartwood of an exogenous tree. 
In botany, duramen is the name given to the central wood or heart-wood in the trunk of an exogenous tree. It is more solid than the newer wood that surrounds it, from the formation of secondary layers of cellulose in the wood cells.
heartwood.