Why do cacti have spines instead of leaves?

Cacti have spines instead of leaves to minimise water loss in arid environments. Unlike leaves, spines have a much smaller surface area, reducing evaporation. They also provide shade and create a microclimate that conserves moisture around the cactus. Spines deter herbivores from eating the plant and serve as a protective barrier against harsh winds and intense sunlight. This adaptation ensures that cacti can survive and thrive in some of the world’s driest regions.