water movement in xylem

• The rate of transpiration depends on factors such as temperature, light intensity, humidity and wind speed
• root pressure


  high osmotic pressure

  • low concentration of water in root cells
  • water from soil moves in
  • pushing water up the stem
  • process of osmosis
• cohesion


  forces of attraction between water molecules
• adhesion


  forces of attraction between water molecules and xylem vessel wall
• capillary action


  the combination of cohesion and adhesion forces that allows water to flow in narrow spaces in opposition to gravitational forces
• transpiration pull


  • the force by which water is pulled up large vertical distances through the xylem
  • to replace water vapour lost through transpiration
• transpiration


  the loss of water vapour by evaporation through the stomata