takes longer with this method. A chair design might take 8 to 10 years to reach maturity. Some of Axel Erlandson's trees took 40 years to assume their finished shapes. Common techniques Some techniques are common to all the above methods though sometimes they are used differently for each. Framing might consist of a combination or any one of several materials, including the tree itself, living or dead. Grafting is a commonly employed technique that exploits the natural biological process of inosculation. A branch is cut and held in place, it can be of the same plant or another cultivar of the plant. Grafting is applied to create permanent connections and joints. Pruning can be used to balance a design by controlling and directing growth into a desired shape. Timing is used as part of the construction is intrinsic to achieving this art form. Structure Living grown structures have a number of structural mechanical advantages over those constructed of lumber and are more resistant to decay. While there are some decay organisms that can rot live wood from the outside, and though living trees can carry decayed and decaying heartwood inside them; in general, living trees decay from the inside out and dead wood decays from the outside in. Living wood tissue, particularly sapwood, wields a very potent defense against decay from either direction, known as compartmentalization. This protection applies to living trees only and varies among species. Growing structures is not as easy as it would seem. Quick growing willows have been used to grow building structures, they provide support or protection. A young group of German architects are in the process of such a structure and they are continually monitored and checked. Once the trees are of age to be able to take on load-bearing weight they are tested for stability and strength by a structural engineer. Once this is approved the supporting framework is removed. Projects are limited to the trees' weight loading ability and growth. This is being studied and the load capacity will be proved by testing on prototypes. Design options Designs may include abstract, symbolic, or functional elements. Some shapes crafted and grown are purely artistic; perhaps cubes, circles, or letters of an alphabet, while other designs might yield any of a wide variety of useful shapes, such as clothes hangers, laundry and wastepaper bins, ladders, furniture, tools, and tool handles. Eye-catching structures such