Question

Deciduous plants shed their leaves during summer or 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.

Answer 1

The anatomical mechanism involved in the abscission of leaves:

1. Structural: In deciduous trees, an abscission zone, also called a separation zone, is formed at the base of the petiole. It is composed of a top layer that has cells with weak walls and a bottom layer that expands in the autumn, breaking the weak walls of the cells in the top layer. This allows the leaf to be shed.
2. The loss of chlorophyll may also contribute to the abscission process.
3. Hormonal: Abscisic acid is the hormone that stimulates abscission (for which the hormone was named).