How do leaves protect themselves from dehydration? 

Some leaves have adaptations to prevent dehydration, such as a waxy cuticle layer to reduce water loss, smaller surface area to volume ratio, curling or closing of stomata during high light or hot periods, and thick, succulent leaves with high water content.

Some leaves will roll up or wilt in response to drought stress, reducing the surface area exposed to the air and thus reducing water loss through transpiration.