Heartwood

heartwood, the central, woody core of a tree, no longer serving for the conduction of water and dissolved minerals; heartwood is usually denser and darker in color than the outer sapwood. Before the synthesis of aniline dyes, the heartwood of several tropical trees (sold collectively under the commercial name brazilwood) was used to produce blue, purple, and red dyes. As a tree becomes older, the heartwood increases in diameter, whereas the sapwood remains about the same thickness. See wood.

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heartwood

Dead, central wood of trees. Its cells usually contain tannins or other substances that make it dark and sometimes fragrant. Heartwood is mechanically strong, resistant to decay, and less easily penetrated by wood-preservative chemicals than other types of wood. One or more layers of living and functional sapwood cells are periodically converted to heartwood.

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heartwood

the central core of dark hard wood in tree trunks, consisting of nonfunctioning xylem tissue that has become blocked with resins, tannins, and oils

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heartwood [′härt‚wu̇d]

(botany)

Xylem of an angiosperm.

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heartwood, duramen

heartwood

Wood at the core of an exogenous tree; normally darker and much more durable than sapwood.

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Heartwood 

the older internal part of the wood of many timber trees. The heartwood is usually darker than the surrounding sapwood (cinnamon-brown in oak, yellow in barberry and acacia, reddish in yew, orange in alder, and almost black in ebony). As a result of the plugging of the vessels and tracheids with tyloses, resins, gums, essential oils, and other substances, the heartwood is almost impermeable to water and air and is resistant to rotting and fungal infestation.