The term 'Burr Walnut' is used in a slightly confusing way. Sometimes it refers to the swirling figure present in nearly all Walnut when cut and polished, and especially in the wood taken from the base of the tree where it joins the roots. However the true burr is a rare growth on the tree where hundreds of tiny branches have started to grow. They are much esteemed for the complex and delightful figure they produce. There are examples of fine furniture made with such wood in the furniture section.
Burrs can attain very large sizes: the one below was harvested in America and weighed 4,000lb.
A burr detached and ready for processing
This rather blurred picture shows a 'two-stage' burr on a tree, again in the USA. We would be very interested in any other pictures of significant burrs - if you have any please send them.
A Walnut with a large burr