Leaf abscission is the controlled process by which a plant sheds a leaf, typically at the end of its functional life or in response to stress. It occurs at a specialized layer of cells at the base of the leaf stalk, called the abscission zone, where cell walls are enzymatically weakened so the leaf can detach cleanly.
In indoor and outdoor plants, abscission is often preceded by senescence, during which nutrients such as nitrogen are withdrawn from the leaf and reused elsewhere. Hormones regulate the process, with ethylene promoting separation and cytokinins generally delaying it. Environmental triggers include seasonal changes, drought, low light, and physical damage.
Leaf abscission differs from leaves dropping due to breakage or disease, where tissue is lost abruptly without a regulated separation layer. A visible, dry “scar” at the node is typical of normal abscission and helps seal the plant against water loss and pathogens.
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