ROOTS  Vascular Cambium, Secondary Phloem and Xylem  | 
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 The vascular cambium arises from the pericycle and the procambium located between the primary phloem and xylem tissues. It forms a thin concentric layer of undifferentiated cells that give rise to secondary phloem tissue toward the outside of the root, and secondary xylem tissue toward the inside of the root. 
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Root Secondary Growth XS   | 
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