In some plants, leaves get modified to perform some special functions other than the normal ones, such as photosynthesis and transpiration. Sometimes these modifications are in response to certain environmental conditions. This type of alteration of leaves is called leaf modification.
Some leaf modifications are as follows:
1. In weak-stemmed plants, leaves are modified into special structures which twine around a support. These are tendrils. These offer support to the plant while climbing up.
2. In some plants like onion, leaves are modified to store food. These are termed to be scaly leaves.
3. In some desert plants like cactus, leaves are reduced to spines so as to reduce the loss of water through transpiration. These spines are also called as thorns. Thorns protect these plants from grazing animals.
4. In some insectivorous plants, leaves are modified into pitchers where they are used to trap insects. These insects can be digested inside the body of the plant. In this way, plants obtain nitrogen from animals.