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 which 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 that the water from the spring
rains disappears—just a few weeks after it falls—such plants no longer need
any. The perennials have special features which 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 a
short time. The small shoot system, on the other hand, considerably limits water
loss by evaporation. Another feature of many desert 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 the 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. Ordinary plants are unable to survive in the desert mainly because of
the changeable weather.