Cacti make use of many structural adaptations, such as shallow roots, fixed spines and thick stems, to survive in the desert where there is minimal rainfall. Each of these adaptations allow the plant to collect and store water more efficiently in an environment where water is scarce.
Cacti do not have leaves, but instead have a fixed spine. The fixed spine loses less water than leaves, so the plant can photosynthesize throughout the dry season. Cacti have very shallow roots to soak up water immediately after rainfall, and they also have thick, expandable stems to store all of the water they absorb from the ground. Because of these adaptations, cacti are able to survive in the desert where most plants would die.