-How plants get liquid and minerals-
Flowers absorb liquid through their roots, which are attached to xylem vessels. Xylem vessels are tubes that can expand through several feet of tissue and be .7mm in diameter. Their walls are thickened with cellulose deposits. Xylem bring water up to the leaves and petals of the plant. Even without contact with the roots, the xylem can still absorb water. Because of this, a cut flower usually doesn’t die for a couple days (as long as it is placed in water of course). The fluid inside of the plants is transported by capillary action. Capillary action is caused by surface tension and adhesion. Adhesion is an attraction between two substances of different states (such as a liquid and a solid). An example of adhesion is water sticking to a glass. “Adhesion of water to the walls of a vessel will cause an upward force on the liquid at the edges and result in a meniscus which turns upward. The surface tension acts to hold the surface intact, so instead of just the edges moving upward, the whole liquid surface is dragged upward. Capillary action occurs when the adhesion to the walls is stronger than the cohesive forces between the liquid molecules. The height to which capillary action will take water in a uniform circular tube is limited by surface tension. The height to which capillary action will lift water depends upon the weight of water which the surface tension will lift.”
(Quote and pictures from: http://hyperphysics.phy-astr.gsu.edu/hbase/surten2.html#c5)
Therefore, the smaller the tube; the smaller amount of water will be allowed into the tube, which means a greater rise of water (as seen in the picture above). But if the liquid is not water, then it will have a different density. A higher density causes a lesser rise because there would be more weight to the same amount of liquid. A lower density would lead to a greater rise because there would be less weight for the same amount of liquid. And so, capillary action...
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