Question

Why do desert plants have leaves reduces to spines?​

Answer 1

They are present in hot deserts which are scarce in water so in order to reduce the loss of water by Transpiration from the surface of the leaves, its leaves are reduced to spines. It prevents or rather protects the cactus plant from being eaten by the desert animals.

Answer 2

Explanation:

They are present in hot deserts which are scarce in water so in order to reduce the loss of water by Transpiration from the surface of the leaves, its leaves are reduced to spines. ... It prevents or rather protects the cactus plant from being eaten by the desert animals.