Transpirationis the evaporation of water from plants. Itoccurschiefly at the leaves while their stomata are open for the passage of CO2and O2during photosynthesis. But air that is not fully saturated with water vapor (100% relative humidity) will dry the surfaces of cells with which it comes in contact.

How transpiration is a diffusion process?

Transpiration (diffusion method) is a major physiological process in plants, by which loss of water from stomatal openings takes place. Stoma (singular stomata) are minute pores present in the foliage, stem, roots, and flowers. In most of the floral species, their number is higher in the lower side of leaves. They are crucial structures for exchanging gases and moisture, between plants and their environment.

Several functions of plants are associated with this process, which takes place when the stomata are open. When you study the detailed structure of a stomata, you will find the guard cells that regulate its opening and closing. The hydrostatic pressure of upper plant parts and soil moisture, collectively play a major role in opening of these structures.

The roots take up water molecules from soil, by means of osmosis, during which essential nutrients are also absorbed. Water and the minerals reach the upper plant parts. As the stoma receives the H2O molecules, the guard cells become flaccid, resulting in opening of the pores. Water is then lost by transpiration, and the cells revert to a normal state resulting in the closing of stoma.