Leaves are primarily meant for photosynthesis, transpiration, and gaseous exchange, but in many plants they undergo modifications to perform special functions. These leaf modifications help plants adapt to their environment.
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1. Leaf Base Modifications
Structures: Pulvinus, Stipule, Leaf sheath
These are modified parts of the leaf base that provide support, protection, or flexibility.
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2. Petiole Modifications
In some plants, the petiole becomes photosynthetic, taking over the function of the lamina (leaf blade).
Example: Australian Acacia (here, the true leaf is reduced and the petiole is flattened and green).
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3. Other Leaf Modifications
(a) Leaf Tendrils
Slender, coiled structures that help in climbing and support.
Example: Pea plant (Pisum sativum) – here, leaf tendrils replace the leaflets.
(b) Fleshy Leaves
Leaves become thick and swollen to store food.
Examples: Onion, Garlic.
(c) Spines
Leaves are reduced to spines to reduce water loss and provide protection against herbivores.
Example: Cactus.
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Quick Recap (Leaf Modifications)
Leaf base: Pulvinus, Stipule, Leaf sheath.
Petiole: Photosynthetic in Australian Acacia.
Leaf tendril: Climbing (Pea plant).
Fleshy leaf: Storage (Onion, Garlic).
Spines: Protection & water conservation (Cactus).
