Push/pull Theory

Part I of Essay
Plants need much more water to survive than animals do, a sunflower must take in 17 times more water than a human of comparable weight. At least 500 pounds of water must be lifted from the roots to the leaves to make a single pound of organic tissue. This tremendous amount ....

Part II of Essay
.... a process called guttation. Through guttation, tiny droplets of water are sometimes forced out of some plants. Guttation only works when soil is almost completely saturated with water and leaves are not losing much water through evaporation. When the xylem is full of water, the molecules will not move back down the structure, but rather need to be expelled from the plant. They will move, by the process of osmosis, to an areas where there is the least amount of pressure. These areas are usually openings located on plant leaves. Once the w ....