How nature uses flexible structures to withstand critical stresses
Some tree species, such as the Scots pine or the Norwegian spruce, have developed an unusual method of withstanding wind loads. They grow spirally, both on the trunk and on the branches. Normal, straight-grown trees have classic tension and compression fields on the branches when subjected to a bending load, e.g. from the wind or snow. If the tensile load on one side becomes too much, the trunk or branch breaks.
Trees that have grown in a spiral guide the tensile and compressive loads from one side to the other by bending and twisting elastically when a load is applied. This has three advantages: The flow of forces does not cause stress peaks, the load is distributed over a larger area and the forces due to wind or snow can no longer attack at a 90° angle and thus lose their effectiveness. Where straight-grown trees would break, spiral-shaped trees withstand the loads and can withstand the weather conditions.
This principle can be used in engineering wherever rod-shaped structures have to withstand high bending loads. For example, in architecture or wind turbines.