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How do vascular rays move materials across 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.
Vascular rays are bands of cells, typically parenchymatous, that extend radially from the cambium into both the xylem and phloem of a plant stem or root. In a cross-section of a tree trunk, these structures appear as spokes of a wheel, radiating from the pith toward the bark.12
Their primary function is to facilitate the radial conduction of fluids and nutrients across the trunk, moving materials between the longitudinal vascular bundles and the surrounding tissues. While the xylem and phloem are responsible for rapid, long-distance transport along the length of the plant, vascular rays provide the necessary lateral pathways to supply tissues located between these primary conducting systems.134