Assertion: secondary xylem | /r/HasProperty | sapwood
Facets:
Source sentences:
text: Thus, in the trunk and older branches of a large tree, only the outer secondary xylem (sapwood) serves in water conduction, while the inner part (heartwood) is composed of dead but structurally strong primary xylem.
text: The functional vessel elements or tracheids occur in a few cell layers behind the vascular cambium, in a water-conducting section of the secondary xylem known as sapwood.