the ground. Turgor pressure within the fruit ranges from .003 to 1.0 MPa. Growth The action of turgor pressure on extensible cell walls is usually said to be the driving force of growth within the cell. An increase of turgor pressure causes expansion of cells and extension of apical cells, pollen tubes, and other plant structures such as root tips. Cell expansion and an increase in turgor pressure is due to inward diffusion of water into the cell, and turgor pressure increases due to the increasing volume of vacuolar sap. A growing root cell's turgor pressure can be up to 0.6 MPa, which is over three times that of a car tire. Epidermal cells in a leaf can have pressures ranging from 1.5 to 2.0 MPa. These high pressures can explain why plants can grow through asphalt and other hard surfaces. Turgidity Turgidity is observed in a cell where the cell membrane is pushed against the cell wall. In some plants, cell walls loosen at a faster rate than water can cross the membrane, which results in cells with lower turgor pressure. Stomata Turgor pressure within the stomata regulates when the stomata can open and close, which plays a role in transpiration rates of the plant. This is also important because this function regulates water loss within the plant. Lower turgor pressure can mean that the cell has a low water concentration and closing the stomata would help to preserve water. High turgor pressure keeps the stomata open for gas exchanges necessary for photosynthesis. Mimosa pudica It has been concluded that loss of turgor pressure within the leaves of Mimosa pudica is responsible for the plant's reaction when touched. Other factors such as changes in osmotic pressure, protoplasmic contraction and increase in cellular permeability have been observed to affect this response. It has also been recorded that turgor pressure is different in the upper and lower pulvinar cells of the plant, and the movement of potassium and calcium ions throughout the cells cause the increase in turgor pressure. When touched, the pulvinus is activated and exudes contractile proteins, which in turn increases turgor pressure and closes the leaves of the plant. Function in other taxa As earlier stated, turgor pressure can be found in other organisms besides plants and can play a large role in the development, movement, and nature of said organisms. Fungi In fungi, turgor pressure has been