Horror, Sleaze and Trash.

The cross section of a tree shows how much trees develop around the pith. Each concentric layer of wood indicates a year’s growth i temperate climates. Trees of the tropics don’t always have such annual rings, but where they do appear they represent extreme contrasts between wet and dry.

A. Outer Bark—The protective skin of a tree. The way bark expands characterizes the species of the tree: some scale off, some create fissures, and some seem almost elastic in their smoothness.

B. Phloem—The sugars produced by the leaves are conducted to the roots and the trunk through this layer.

C. Cambium Layer—Produces new wood and bark by the creation of cells.
D. Xylem (Sapwood)—Through this layer moisture runs from the roots to the leaves and evaporates. This is the tree’s “living” tissue. The sapwood is almost always lighter in color than the heartwood, producing delightful contrasts, but it is typically regarded as undesirable for fine wood-working. It is usually softer than the heartwood.

E. Heartwood—The bulk of the tree, composed of cells no longer carrying vital juices—essentially dead. In some instances, the heartwood decays, leaving the tree a living shell.

F. Early Growth—Fast growth of the tree in its youth. This heartwood is often knotty and therefore inferior.

G. Pith—Where it all started.