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Tree
Fern Aerial Root
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| A cross-section of this aerial root, found in the mantle of a tree fern, reveals the central, star-shaped xylem strand. As the aerial root developed, primary xylem grew from five different points. Metaxylem was then produced towards the center forming a star shape. Phloem tissue developed between the arms of the star. The aerial rootlet pictured above comes from a permian aged Brazilian tree fern (Titea singularis). The picture was taken at 40x. |