Transpiration & Translocation

• Transpiration


  The process of water constantly evaporating from the surfaces of leaves
• Transpiration


  1. Water evaporates from cells inside the leaf

  2. Water vapor diffuses through the air spaces in the spongy mesophyll

  3. Water vapor exits the leaf through the stomata

  4. Water passes from the xylem into the leaf to replace the water that's being lost

  5. Water is drawn into the root hair cells and up the xylem vessels to the leaf
• Transpiration


  • Brings water to the leaf for photosynthesis
  • Transports dissolved mineral ions such as magnesium
  • Cools the leaf down in warm weather
• Factors affecting the rate of transpiration


  • Higher temperatures
  • Dry conditions with low humidity
  • Windy conditions
  • Higher light intensity
• Higher light intensity


  Stomata open to allow carbon dioxide to enter for photosynthesis, allowing water vapor to pass out
• Stomata


  Pores on the leaf surface surrounded by two guard cells
• Stomata opening and closing


  1. Guard cells swell and change shape in high light, causing stomata to open

  2. Plant closes stomata under hot conditions to reduce water loss