sapwood, relatively thin, youngest, outer part of the woody stem of a tree, the part that conducts water and dissolved materials. In the cross section of a tree, the sapwood is recognizable by its texture and color; it is softer and lighter than the inner heartwood. As the tree grows in diameter, the innermost layers of sapwood become heartwood, and new sapwood is produced on the outside of the woody column. See wood.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.