Figure 1. The generation of turgor pressure in plant cells. (a) Solutes are actively pumped across the semipermeable membrane of the protoplast. (b) Water crosses the membrane by osmosis, causing the protoplast to swell. In the absence of a cell wall this would continue until the protoplast burst. (c) In plant cells, solutes and water are accumulated in a protoplast contained within a cell wall. (d) Swelling of the protoplast restricted by the cell wall generates the turgor pressure.

Figure 2. Approximate hydrostatic pressures (turgor) found in a range of situations for comparison with those in cells of vascular plants. Heart: pressure generated in animal circulation. Alga: pressures found in intertidal algae bathed in fresh water. Turbine: approximate pressures generated in the steam turbines of power stations.