The capillarity of plants is a physical phenomenon that allows a liquid, in this case water, climb very thin tube to feed the plant. These very fine tubes are called capillaries, and the physical phenomenon is called capillarity.
Plants absorb water and nutrients from the soil through their roots. From there it is transported and distributed throughout the plant by capillary conductive vessels. The water absorbed by the plant mixes with mineral salts forming the sap. It must go a long way through the xylem (stem), until it reaches the leaves, where photosynthesis takes place.
How does the capillarity of plants work?
In plants, once they absorb water, it is transported by a system of cells that make up plant tissue. Externally it is protected by a layer of dead tissues. They prevent perspiration and fluid loss through the stem.
The xylem or stem is made up of several types of cells, some of them are elongated and very fine. They have a cavity at each end.
When coupled with each other, they form small pipes or circulation networks. Through there the water is transported from one cell to another, by pressure difference. At this point is where the phenomenon of capillarity intervenes.
Cohesion theory
This theory says that the sap moves up the stem through a suction force. This is caused by the tension generated within the capillaries by the perspiration of the leaves, and by the cohesion between the water molecules.
Solar energy causes the sap to circulate through the stomata of the leaves, causing perspiration. This is generated if there is a continuous cycle of water supply in the stem, and it is possible if the suction force is constant.
The cohesive force of the water molecules causes the perspiration to generate enough tension to maintain the water column within the stem. In this way, the water molecules do not rise one by one, but form a chain.
The strong adhesion of water to the walls of the tubes within the stem is made possible by capillarity. Summarizing; Through root pressure the water is sent into the plant by osmotic pressure.
Due to the heating by solar energy, perspiration occurs. This removal of water produces a suction effect due to the cohesion force between the water molecules.
Example
If you place a plant, for example celery, in a glass of water with some coloring, and leave it for a few days, you will be able to notice how the plant transported the water through the capillaries.
You can see how the plant distributes the sap from the stem to its leaves through the dye that the capillaries take.
If we put the glass in the sun for a few hours we will also see that the water level drops, due to perspiration, generating the phenomenon of capillarity.
References
- academia.edu
- en.wikipedia.org
- scoop.it
- sabercurioso.es
- fq-experimentos.blogspot.com.ar
- blacks-guarnizo.blogspot.com.ar
- definition of
- biologia-fisiovegetal.blogspot.com.ar
- educacioncreativa.es.