<P> 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 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 . </P> <P> Transpiration can be regulated through stomatal closure or opening . It allows for plants to efficiently transport water up to their highest body organs, regulate the temperature of stem and leaves and it allows for upstream signaling such as the dispersal of an apoplastic alkalinization during local oxidative stress . </P> <P> Summary of water movement: </P> <Ol> <Li> Soil </Li> <Li> Roots and Root Hair </Li> <Li> Xylem </Li> <Li> Leaves </Li> <Li> Air </Li> </Ol>

Describe how transpiration helps in transport of water in a plant