This burl walnut writing desk has a lovely leather slope as well as side flaps that extend the working space.   Burl walnut (American English) or Burr walnut (British English) is wood harvested from the base of walnut trees, where a large ball often occurs. The burl itself is an abnormal growth or deformity on the tree, often caused by some sort of stress such as a virus or bug infestation. When cut, the burl has a distinct appearance that can be finished to create an attractive piece of furniture or other structure. Walnut burl wood exhibits a rich dark color with deep, complex grain patterns, and is often used in crafting high-end furniture, veneers, and decorative items.