root pressure Word Origin noun Botany.
- osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves.
Origin of root pressure First recorded in 1870–75 root pressure in Science root pressure
- Pressure produced in the roots of plants, causing exudation of sap from cut stems and guttation of water from leaves. The pressure is generated by the concentration of solutes in the xylem of the root and stem, which in turn causes water to move into the xylem by osmosis.