Transpiration
/ˌtrænspəˈreɪʃən/
Definition
Transpiration is the plant process of losing water vapor to the air, mainly through tiny leaf pores called stomata, and to a lesser extent through stems and other surfaces. As water evaporates from these tissues, it helps pull more water and dissolved minerals upward from the roots through the xylem, the plant’s water-conducting tissue. It differs from photosynthesis because it moves water rather than making sugars.
Biological Role
- Water movement through xylem: transpiration helps pull water upward from roots through xylem, the tissue that conducts water. This flow also carries dissolved minerals to leaves and other growing parts.
- Leaf cooling effect: As water evaporates from leaf surfaces, transpiration helps moderate leaf temperature. This can reduce heat stress when light and air temperature are high.
- Response to stomata: The rate is closely linked to stomata, the tiny pores that open and close on leaves. When stomata close to conserve water, carbon dioxide entry for photosynthesis also drops.
- Environmental influence: Light, temperature, humidity, wind, and soil moisture all affect transpiration. In dry air or wind, water loss often rises, which can lead to wilting if roots cannot replace it fast enough.
Related Terms
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Xylem
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