Plants in Desert
Only special plants can survive the terrible climate of a desert, for these are regions where the
annual range of the soil temperature can be over 75℃. Furthermore, during the summer there are
few clouds in the sky to protect plants from the sun's ray.Another problem is the fact that there are
frequently strong winds that drive small, sharp particles of sand into the plants, tearing and
damaging them. The most difficult problem for all forms of plant life, however, is the fact that the
entire annual rainfall occurs during a few days or weeks in spring.
Grasses and flowers in 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 insufficient rain falls, they wait until the next year, or even still the next.
Another factor that helps these plants to survive is the fact that their life cycles are short. By the
time the water from the spring rains disappears—just a few weeks after it falls—such plants no
longer need any.
The perennials (多年生植物) have special features that enable them to survive as plants for
several years. Thus, nearly all desert perennials 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 short time. The small shoot system, on the other hand, considerably limits
water loss by evaporation (蒸发).
Another feature of many perennials is that after the rainy season they lose their leaves in
preparation for the long, dry season, just as trees in wetter climates lose theirs in preparation for
the winter. This reduces their water loss by evaporation during the dry season. Then, in next rainy
season, they come fully alive once more, and grow new branches, leaves and flowers, just as the
grasses and flowers in desert do.