Abscission
/ab-SIZH-un/🔬 Anatomy●● Intermediate
Also known as: leaf drop, leaf fall
Abscission is the controlled separation of plant organs from the parent plant through the development of a specialized abscission zone — a layer of cells at the base of the organ that weakens and eventually separates. This process is regulated by the balance of auxin (which inhibits abscission) and ethylene (which promotes it). Autumn leaf drop is the most visible example, but flowers, fruit, and branches are also abscised.
Etymology
From Latin abscissio (a cutting off), from abscindere (to cut off)
Example
“The abscission zone at the leaf base weakened as ethylene levels increased, preparing the tree for autumn leaf drop.”