Deciduous plants shed their leaves during hot summer of in autumn. This process of shedding of leaves is called abscission. Apart from physiological changes what anatomical mechanism is involved in the abscission of leaves.

Explanation

Abscission zones occur at the base of leaf petioles. Leaves are shed through number of biological actions which weaken cell walls and initiate the cells tearing away from one another.
Abscission zone is composed of :
(a) A cell wall degradation area
(b) A shear force generation area
(c) A tree protection zone
Abscission zone cells secrete pectinase and cellulase.
The middle lamella .glue. which holds cell together, begins to dissolve in abscission zone.