In all hardwood trees, there are two types of wood: the sapwood and the heartwood. The heartwood is the dense inner part of a tree that yields the hardest wood. It is literally the heart of the tree.
In woodworking, this is the lumber that is most often used for projects, and what is sought after. It can only be gained from a tree by having the patience to allow the layers of sapwood to convert to heartwood and build over time. The beauty of not only that process, but the process to work with the wood to bring out the detail of flow of the grain in fished projects, is why I love woodworking.
Materials or Construction
The darker stripes are Walnut, the lighter ones are Cherry. The wood strips would be 4 to 6 inches wide, depending on the math to get full lines from top to bottom.