sapwood

The newly formed outer wood located just inside the vascular cambium of a tree trunk and active in the conduction of water. Sapwood is usually lighter in color than heartwood.

Alburnum.

The alburnum, or part of the wood of any exogenous tree next to the bark, being that portion of the tree through which the sap flows most freely; — distinguished from heartwood.

The wood just under the bark of a stem or branch, different in color from the heartwood

newly formed outer wood lying between the cambium and the heartwood of a tree or woody plant; usually light colored; active in water conduction