(1) Root hair plays an important role in absorption of water by osmosis.
(2) Root hairs grow out into the spaces between the soil particles and that the hairs are surrounded by moisture.
(3) The soil water is more dilute than that of the cellsap in the root hair, therefore water will pass into the vacuole of the root hair by osmosis.
(4) The entry of water dilutes the contents of the root hair vacuole so that it becomes weaker than its neighbour.
(5) Therefore water passes into the neighbouring cell which in turn becomes diluted, finally water enters the xylem vessels.
(6) As there are vast number of root hairs and root cells involved, a pressure in the xylem vessels develops which forces the water upwards.
(7) This total pressure is known as root pressure.
(8) Root pressure is not the main cause of movement of water in xylem but it is certainly one factor.
