The Heart Pith is the spongy center of the tree that appears on the surface of the board. The true pith is the size of a pencil or ¼" in diameter, but it may move around a lot in crooked trees. In addition to the pith the first 3 or 4 growth rings are pretty immature and should be treated with caution. As these underdeveloped sections dry out they can open up and curl at the edges. You will probably want to cut out this section.