abscission

noun

(L. abscindere, to cut off) The normal shedding, separation, from the body of a plant, caused by the breakdown of thin-walled cells at the base of a structure, of an organ that is mature or aged, e.g. a ripe fruit, an old leaf. The process is controlled by growth substances, notably auxins; it involves the formation of an abscission zone, at the base of the part, within which a layer of cells (abscission layer) breaks down. Also cladoptosis.