xylem
one of the two types of transport tissue in vascular plants
sapwood
the part of living wood where sap flows, as distinct from the heartwood, where it doesn't
tracheid
capillary tube formed from a series of dead lignified cells in the xylem, or single such cell, water conducting and relatively broad, where at least the primary cell wall remains intact, and the walls are lignified, being variously banded or pitted