Plants in Desert

Only special plantscan survive the terrible climate of a desert,for these are regions where the annualrange 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 flowers in desert survive from one year to the next byexisting through the long,hot,dry season in the form of seeds.These seedsremain

inactive unless theright amount of rain falls.If no rain falls,or if insufficient rain falls,theywait until the next year,or even still the next.Another factor that helps theseplants

to survive is thefact that their life cycles are short.By the time the water from the springrains disappears-just a few weeks after it falls-such plants no longer needany.

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 shoot system,on

the otherhand,considerably limits water ioss 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.Winter is thetoughest season for the grasses and flowers to surviVe.

A.Right

B.Wrong

C.Not mentioned