|MadSci Network: Botany|
The leaf scar occurs because the stem has to heal over the area where the leaf was attached to prevent disease entry and water and nutrient loss. It is especially important to seal off the vascular connections (xylem and phloem) that carried water and dissolved substances into and out of the leaf. The orderly process of leaf death or senescence ends with the dropping or abscission of the leaf. An abscission zone forms before the leaf drops. Leaf scars are often useful for identifying deciduous trees and shrubs when they are leafless. A person who loses a limb or finger would also have a scar where the wound healed over. References Plant Stem Growth Leaf Abscission
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