The main function of the leaves is to carry out the process of photosynthesis. However, in a few plants, leaves are modified to perform different functions.

$(a)$ Tendrils: The leaves of a pea plant are modified into tendrils that help the plant in climbing.

$(b)$ Spines: The leaves in cactus are modified into sharp spines that act as an organ of defence.

$(c)$ Phyllode: The leaves of some Australian acacia are short-lived and soon replaced by flattened, green structures called phyllodes that arise from the petiole of the leaves.

The petioles in these plants synthesize food.

$(d)$ Pitcher: The leaves of the pitcher plant are modified into pitcher-like structures, which contain digestive juices and help in trapping and digesting insects.