Leaves, fruits, flowers, and other parts of plants contain a layer of cells called an “abscission layer” or “abscission zone” which are cells that are meant to weaken and expand to push – or cut – part of the plant away from the base. This is seen in deciduous trees at the base of the petiole, and is responsible for leaves falling in autumn.
A phytohormone called ethylene is largely responsible for leaf abscission, especially in conjunction with auxin. Loss of auxin makes the plant more susceptible to the effects of ethylene.
Pests, temperature, changes in chlorophyll, as well as other phytohormones may be responsible for abscission depending on the plant type and environment.
When abscission cells are triggered, they begin to push against the healthy cells, halting the transport of nutrients and severing their connection with the plant’s base. Over a few days to a few weeks, these abscission cells grow and push the leaf, fruit, flower, or other organ away from the base.« Back to Glossary Index