How do the various leaf modifications help plants?

(N/A) The primary function of leaves is photosynthesis. However,in some plants,leaves are modified to perform specialized functions:
$(a)$ Tendrils: In plants like peas,leaves are modified into thread-like structures called tendrils,which provide support and help the plant in climbing.
$(b)$ Spines: In plants like cactus,leaves are modified into sharp spines,which act as a defensive organ against herbivores and reduce water loss.
$(c)$ Phyllode: In some Australian acacia species,the leaves are short-lived and are replaced by flattened,green,leaf-like structures called phyllodes that develop from the petiole. These structures perform photosynthesis.
$(d)$ Pitcher: In insectivorous plants like the pitcher plant,leaves are modified into pitcher-like structures that trap and digest insects to obtain nitrogen.