Do the leaves of all plants have an abscission layer If not

Do the leaves of all plants have an abscission layer? If not, what happens to the leaves on such plants?

Solution

Plants exhibit the phenomenon of abscission when it no longer needs its parts like leaves, flowers and fruits. Most of the plants undergo abscission to conserve nutrients and energy. Almost all plants and trees of deciduous, coniferous and rain forests shed leaves by forming abscission layer. Abscission layer formation shed the plant part with deposition of secondary structures made up of parenchyma, suberin and lignin as a protective layer.

Abscission in plants take place under 3 major conditions- 1. to conserve water and photosynthetic energy; 2. to resist the pests or as part defense mechanism and 3. to improve photosynthetic efficiency of plants. Generally, the leaves that became older are shed through abscission. This is because, the older leaves lose chlorophylls and may develop other pigments like carotenes, xanthophylls and anthocyanins abundantly. If abscission does not take place, the older leaves remaining on plant may not carry out photosynthesis efficiently as a chlorophyllous leaf does. Due to this plant may exhibit poor growth and nutrient deficiency and may even die due to inadequate nutrient synthesis.