B8.3 Transpiration

What is transpiration?

Transpiration is the loss of water vapor from the leaves of a plant. Water evaporates from the surface of the spongy mesophyll cells inside the leaf and then diffuses out through the stomata.

What factors affect transpiration and why?

- Temperature: if temperature is increased, theres a higher rate of transpiration. Higher temperatures increase evaporation, which cools the plant.

- Wind speed: the faster the wind, the more water vapour is swept away from the surface of the leaves

Why does wilting happen?

When plants lose more water than they are gaining, they become flaccid. The flaccid cells lose their rigidity and the stems and leaves of the plant wilt.

What are the advantages and disadvantages of transpiration?

• Advantage: helps the plant cool on a hot day as water evaporates

• Disadvantage: the plant can lose too much water