Besides their usual function of photosynthesis leaves may be modified to perform other functions as well. Some of the important modifications of leaves are:
1. Tendril: In some plants, the entire leaf or leaflet becomes tendrillar for the purpose of climbing, e.g. sweet and wild peas, and glory lily.
2. Spines: In a number of plants, leaves become spiny and serve the purpose of defence, e.g. Opuntia, Argemone and Aloe.
3. Hooks: In Bignonia unguis cati three terminal leaflets of compound leaf are modified into claw like hooks which help the plant in climbing.
4. Scaly leaves: In onion leaves are in the form of fleshy scales. These are known as scalyleaves.
5. Pitcher: In some insectivorous plants such as pitcher plant (Nepenthes), the lamina assumes the form of a pitcher with a lid to trap the insects. The inner walls of the pitchers possess a number of digestive glands that secrete a fluid.
6. Phyllode: When the petiole becomes leaf-like, it is termed phyllodes, e.g. Australian Acacia.
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