Leaves are often modified to perform functions other than photosynthesis. They are converted into tendrils for climbing as in peas or into spines for defence as in cacti (Figure: a, b). The fleshy leaves of onion and garlic store food (Figure: c).
Fig: Modifications of leaf for: (a) support: tendril (h) protection: spines (c) storage: fleshy leaves
In some plants such as Australian acacia, the leaves are small and short-lived. The petioles in these plants expand, become green and synthesize food. Leaves of certain insectivorous plants such as pitcher plant, venus-fly trap are also modified leaves.