[EverAshwood]

X is for Xylem

("A vascular cylinder located in the center of the stem of all superior plants. It is made of very long, cylindrical, and most commonly dead cells, that are responsible for conducting water and minerals from the roots to the leaves, where it will be used for photosynthesis. In woody plants, the xylem usually is the most resistant part of the trunk. Herbaceous plants have xylem too, but it´s flexible due to the lack of lignin in its cell walls.
If you chop a log, you will notice a central circle, sometimes with a different color from the outter circle. The inner circle is the xylem.")