plant growth & development
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Transpiration
When a leaf's guard cells shrink, its stomata open, and water is lost. This process is called transpiration. In turn, more water is pulled through the plant from the roots. The rate of transpiration is directly related to whether stomata are open or closed. Stomata account for only 1 percent of a leaf's surface but 90 percent of the water transpired.
Transpiration is a necessary process and uses about 90 percent of the water that enters a plant's roots. The other 10 percent is used in chemical reactions and in plant tissues. Transpiration is responsible for several things:
- Transporting minerals from the soil throughout the plant.
- Cooling the plant through evaporation.
- Moving sugars and plant chemicals.
- Maintaining turgor pressure.
The amount and rate of water loss depends on factors such as temperature, humidity, and wind or air movement. Transpiration often is greatest in hot, dry (low relative humidity), windy weather.
View the transpiration process in illustrated form as a mini-movie or slide set.
