The primary function of the leaves is to manufacture food by the process of photosynthesis. The leaves contain a green pigment called chlorophyll. Chlorophyll traps sunlight which is the sourer of energy to the plant. The leaves make glucose from water and carbon dioxide in the presence of chlorophyll and sunlight.
2. Interchange of Gases:
Leaves have numerous tiny openings called stomata. Through these minute pores exchange of oxygen and carbon dioxide occurs during photosynthesis and respiration. During photosynthesis, carbon dioxide enters the leaves and oxygen is given out while during respiration, oxygen enters the leaves and carbon dioxide is given out.
3. Evaporation of Water:
The excess water present in the plant evaporates through stomata on the leaves. This process is called transpiration.
4. Storage of Food:
In onion the fleshy leaves or scales of onion store water and food in them. Fleshy and succulent leaves of desert plants always store some water and food in them.
5. Vegetative Propagation:
Leaves of some plants produce buds on them. These buds can grow into new plants. Such leaves are found in Bryophyllum and Begonia.