Xerophytes

• Xerophytes

  Plants adapted to live in arid environments - they have developed specialised features that minimise water loss, while allowing for gas exchange
• Problems

  • water moves passively along a concentration gradient out of the plant and into the dry environment
  • rate of water loss by evaporation due to transpiration is very high as there's a high concentration gradient between the inside and outside of the leaf
  • water vapour evaporates and diffuses more quickly in arid environments
  • plant cells can become flaccid, wilt, dry out and die when their water content falls below its tolerance range
  • water is required for photosynthesis, evaporative cooling, and for soil nutrients to dissolve into to be absorbed by the plant
• Adaptations

  Structural:

  • thick waxy cuticle
  • small leaf SA
  • sunken stomata
  • hairy stomata
  • rolled leaves
  • shallow spreading roots

  Physiological:

  • stomata open at night
  • storage of water in succulent tissues