Fig. 15.2-7. Radial section of balsam fir (Abies balsamea). These ray parenchyma cells shown here were still alive when the sample was collected (arrows indicate several nuclei). The sample must have been taken from the sapwood of a living tree, then preserved with FAA or some other fixative. Very often, wood samples are taken from dead pieces of lumber, so all cells in the microscope slide are empty, giving the impression that all wood always consists of dead cells. But in fact, the sapwood of all trees has a considerable amount of living parenchyma cells, at least in the rays.

            There are no ray tracheids here.