The Water Circuit of the Plants - Do Plants have Hearts ?
  There is a correspondence between the circulation of blood in all higher animals and the circulation of sap in all higher plants - up to heights h of 140 m - through the xylem and phloem vessels. Plants suck in water from the soil, osmotically through the roothair zone, and subsequently lift it osmotically again, and by capillary suction (via their buds, leaves, and fruits) into their crowns. In between happens a reverse osmosis - the endodermis jump - realized by two layers of subcellular mechanical pumps in the endodermis walls which are powered by ATP, or in addition by two analogous layers of such pumps in the exodermis. The thus established root pressure helps forcing the absorbed ground water upward, through the whole plant, and often out again, in the form of guttation, or exudation. 
Wolfgang Kundt and Eva Gruber