Leaf abscission.

Abscission is controlled by a change in the balance of ethylene and auxin; a higher proportion of ethylene causes the cells to produce enzymes that digest the cellulose of cell walls.

A layer of cork forms a leaf scar that protects the plant.

A dying maple shows a mixture of colors from the presence of pigments such as carotenoids (yellow, orange) and anthocyanins (red, purple, or blue).