Final answer:
Desert plants possess either deep taproots to reach deep water sources during droughts or shallow fibrous root systems to quickly absorb surface moisture following rainfalls and to provide stability against the erosive desert environment.
Step-by-step explanation:
Desert plants have evolved with specialized root systems to survive in environments with low and unpredictable precipitation. Some plants have deep taproots that can plunge up to 20-30 feet underground to reach moist soil regions, providing an advantage in accessing water from deeper sources after rainfalls. This adaptation allows these plants to sustain themselves during prolonged periods of drought by tapping into groundwater reserves that are not available to plants with shallower roots.
On the other hand, other plants have developed fibrous root systems that spread out widely just beneath the surface. These roots are beneficial in quickly absorbing water from light rainfalls that do not penetrate deeply into the soil. A fibrous root system also helps to anchor plants in the desert, giving them stability against harsh winds and preventing soil erosion around the plant.
In summary, the deep taproot system is advantageous for reaching deep water reserves, thus supporting the plant during extended droughts, while the shallow fibrous root system rapidly absorbs surface moisture following rainfalls and provides stability in the loose desert soil.