Transpiration stream
![Overview of transpiration.
1-Water is passively transported into the roots and then into the xylem.
2-The forces of cohesion and adhesion cause the water molecules to form a column in the xylem.
3- Water moves from the xylem into the mesophyll cells, evaporates from their surfaces and leaves the plant by diffusion through the stomata.](/Images/godic/202502/17/Transpiration_Overview.svg4535.png")
In plants, the transpiration stream is the uninterrupted stream of water and solutes which is taken up by the roots and transported via the xylem vessels to the leaves where it evaporates into the air/apoplast-interface of the substomatal cavity. It is driven by capillary action and in some plants by root pressure. The main driving factor is the difference in water potential between the soil and the substomatal cavity caused by transpiration.