What is transpiration and what factors affect its rate of occurrence? Describe some adaptations of xerophytic plant that reduce water loss via transpiration.

Transpiration is the evaporation of water through open stomata, occurring down the water potential gradient.Factors affecting the rate of transpiration:Light intensity - more stomata will be open to take in CO2 for photosynthesis.Temperature - at higher temperatures water particles will have more energy so the rate of diffusion/evaporation will be greater.Humidity - the lower the humidity, the faster the rate of transpiration because the water potential gradient will be larger.Wind - the more windy the conditions, the faster the rate of transpiration because there will be a greater movement of water particles in the air which will maintain a steeper water potential gradient.Adaptations of xerophytic plants:Sunken stomata - traps water vapour, reducing the concentration gradient of water between the leaf and the air and, therefore, reduces the rate of diffusion (as rate is dependent on size of conc. gradient). Epidermial hairs- also trap water vapour.Curled leaves - traps water vapour and protects the stomata from the wind as reduced airflow helps to maintain a low concentration gradient of water between the leaf and air. Reduced number of stomata - few holes for water to evaporate from. Thick, waxy cuticle on the leaf and stem surface to reduce evaporation through the epidermis.