What does a cactus plant use for making shelter?

A cactus plant tends to dominate its environment, particularly if that habitat is the desert. In such a bright, dry, hot niche, the cactus tends to be the main form of vegetation. Any other vegetation tends to be the understory to the cactus, and not the other way around, except in the jungle.

So a cactus plant tends to use its own body parts as its shelter. The main sheltering body part is the thickened stem to move, process and store nutrient solutions and photosynthetic products. Another is the modified leaf in the form of thorns, spines, spikes, quills, prongs, needles, hairs or bristles. The modified leaf protects the plant from predators.