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How does spiral grain affect the path of water through a tree trunk?
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wood
Temperate softwoods (left column) and hardwoods (right column), selected to highlight natural variations in colour and figure: (A) Douglas fir, (B) sugar pine, (C) redwood, (D) white oak, (E) American sycamore, and (F) black cherry. Each image shows (from left to right) transverse, radial, and tangential surfaces. Click on an individual image for an enlarged view.
In a tree trunk, water-conducting tissues—specifically the xylem—rarely run in a perfectly straight vertical line. Instead, they are typically arranged in a helical or spiral pattern known as spiral grain.1
Because the angle of this spiral arrangement often changes from year to year, the path that water takes as it moves up the stem can become quite complex, especially when multiple growth layers are actively conducting water. Functionally, this spiral grain serves to distribute water from any individual root to all parts of the tree, ensuring that water is effectively dispersed throughout the canopy.1