Fig. 15.2-6. Radial section of white pine wood. The two arrows indicate rows of ray tracheids, the upper row is almost complete but much of the lower row was cut away by the microtome knife.

            Notice that the ray appears to simply end at the arrows. Rays can begin and end, but never as abruptly as this. This ray has not really ended, it is just that the knife was not cutting perfectly parallel to the ray, so the ray has passed out of the section. Although we call this a radial section, if it were really, truly radial, the ray would be present from one side of the section to the other.