Only special plants can survive the terrible climate of a desert, for these are regions where the soil temperature throughout the year can be over 75℃. Furthermore, during the summer there are few clouds in the sky to protect plants from the sun’s rays. Another problem is the fact that there are frequently strong winds that drive small, sharp sands into the plants, tearing and damaging them. The most difficult problem for all forms of plant life, however, is the fact that each year the entire amount of rainfall occurs during a few days or weeks in spring.
Grasses and flowers in a desert survive from one year to the next by existing through the long, hot, dry season in the form of seeds. These seeds remain inactive unless the right amount of rain falls. If no rain falls, or if there is not enough rainfall, they wait until the next year, or even still the next.
Some plants have special elements that enable them to survive as long as several years. Nearly all of them have extensive root systems below ground and a small shoot system above ground. The large root network enables the plant to absorb as much water as possible in a short time. The small shoot system, on the other hand, considerably limits water loss by evaporation (蒸发).