Plants in Desert

Only special plantscan survive the terrible climate of a desert,for these are regions where theannual range of the soil temperature can be over 75℃．Furthermore,during the

summer there are fewclouds in the sky to protect plants from the sun's ray.Another problem is thefact that there are frequently strong winds that drive small,sharp particles of

sand into theplants,tearing and damaging them.The most difficult problem for all forms ofplant life,however,is the fact that the entire annual rainfall occurs during afew

days or weeks inspring.

Grasses and flowersin desert survive from one year to the next by existing through thelong,hot,dry season in the form of seeds.These seeds remain inactive unless theright

amount of rainfalls.If no rain falls,or if insufficient rain falls,they wait until the nextyear,or even still the next.Another factor that helps these plants to surviveis the fact that

their life cyclesare short.By the time the water from the spring rains disappears-just a fewweeks after it falls-such plants no longer need any.

The perennials（多年生植物）have special features thatenable them to survive as plants for several years.Thus,nearly all desertperennials have extensive root systems

below ground and asmall shoot system above ground.The large root network enables the plant toabsorb as much water as possible in short time.

The small shootsystem,on the other hand,considerably limits water loss by evaporation（蒸发）.

Another feature ofmany perennials is that after the rainy season they lose their leaves inpreparation for the long,dry season,just as trees in wetter climates losetheirs in

preparation for thewinter.This reduces their water loss by evaporation during the dryseason.Then,in next rainy season,they come fully alive once more,and grow new

branches,leaves andflowers,just as the grasses and flowers in desert do.The theme of thesecond last paragraph is why the perennials can survive as plants for severalyears.

A.Right

B.Wrong

C.Not mentioned