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.
A.Right
B.Wrong
C.Not mentioned
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de
[单选题]Plants in DesertOnly special plantscan survive the terrible climate of a de