How does a cactus survive in the desert?

Cacti are highly adapted to survive in arid desert environments. Their thick, fleshy stems store water, which they use during prolonged dry periods. The outer layer of the stem is covered with a waxy coating that minimises water loss. Instead of leaves, cacti have spines, which reduce water evaporation and protect the plant from herbivores. Their roots spread widely and remain close to the surface to quickly absorb rainwater. Many cacti also have specialised photosynthesis called CAM (Crassulacean Acid Metabolism), which allows them to open their stomata at night to reduce water loss.