• Evaporation?takes place from the surfaces of spongy mesophyll cells
• The?many interconnecting air spaces?between these cells and the stomata create a?large surface area
• This means evaporation can happen rapidly?when stomata are open

• Water molecules are attracted to each other by?cohesion?- creating a continuous column of water up the plant
• Water moves through the xylem vessels in a continuous?transpiration stream?from roots to leaves via the stem
• Transpiration produces a?tension?or ‘pull’ on the water in the xylem vessels by the leaves
• As water molecules are held together by?cohesive forces?(each individual molecule ‘pulls’ on the one below it), so water is pulled up through the plant
• If the rate of transpiration from the leaves?increases, water molecules are pulled up the xylem vessels?quicker

The generation of the transpiration stream.

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