For this purpose, huge walnut plantations are established in California, where the European walnut tree (Juglans nigra) is grafted onto the American walnut tree (Juglans regia). In the process, root burls are formed underneath the graft. These tubers, after the bearing capacity of the trees for nuts is exhausted, are dug up and sold as a „secondary product“. Uses: European walnut burl is used for the highest quality interior finishes and furniture making. In large quantities for dashboards in the automotive industry and sought after as solid wood for gear knobs. Also used in piano and grand piano construction for high quality instruments. Properties: Color is light to dark brown, mouse gray, often dark veined. Certain furniture styles were firmly associated with the use of European walnut (e.g. Queen Anne era, GB). Special features: Logs are usually excavated with the root, as this is used to make the valuable head veneers. Walnut burl occurs in many manifestations: from head veneer to half burl (cluster) to full burl, which is still one of the most expensive and sought-after veneers.