root pressure


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Fig. 272 Root pressure . The mercury enables root pressure to be measured.

root pressure

a force exerted within a plant root that pushes water up towards the stem. The phenomenon is produced by the root cells having a solute concentration gradient which increases from outside the root towards the centre of the root. Thus, by OSMOSIS, water passes from the soil, across the root and into the xylem as a result of salt excretion by the ENDODERMIS into the xylem, creating pressure which can be observed in a plant with the aerial parts removed.