Inspite of water being an essential component of plant cells, instead of conserving, they lose water from their surfaces. By doing so they themselves get into peril, but they also benefit by this process. By the quirk of nature, plants have no control over the loss of water, because it is the environment factors that force the plant to loose water in the form of water vapors or sometimes in liquid form. Nonetheless, many plants belonging to various taxons are adopted to check excessive loss of water and also conserve water. The process by which plants loose water in liquid form is called Guttation; on the other hand, if the water is lost from the plant body in the form of water vapors, then the phenomenon is called Transpiration, which is often referred to as an unavoidable evil process.
Plants which loose water by guttation are restricted to few taxons in the plant kingdom; hardly there are 150 – 250 plants – ex. Tomato, grasses, colochasia, cucurbita members, balsam, etc. Colochasia, an aquatic plant has been found to loose more than 250 ml of water per day. Otherwise, the amount of water lost by guttation is hardly of any significance. Unlike transpiration process, guttation takes place only under certain conditions like high relative humidity in the atmosphere and plants of water in the soil.
Naturally grown fresh fruits and vegetables, for example, are rich in biophotons. It’s obvious. You need not be a mystic who can see auras to understand. The reality of light waves, or biophotons energy, is obvious to any receptive and discerning eye.
Biophotons shown below, elevate the organism – such as your physical body – to a higher oscillation. As I read that, basically, if you eat fresh, clean food grown on healthy natural land, you support your body at a higher, healthier vibe.
The water that is lost in this process is not pure but contains minerals, organic acids, sugars and even enzymes. The estimation of solutes lost in this process, reveal that certain plants loose about 200-500 mg of solutes per liter of water. On evaporation, the solutes that remain at the margins or tips of leaves cause salt burning, which is often called Guttation burn. The liquid drops that are exuded from the leaves are always through special structures called water stomata or hydathodes. Sometimes, the droplets found at the margin or apex, where hydathodes present, look like dew drops, but they are actually, the liquid drops that are forced out by guttation process.
Hydathodes are specialized structures and they are mainly responsible for secreting water in liquid form. They are generally restricted to the apex or the serrated edges of the margins of leaves.
Structurally, hydathodes consist of a simple pore in the epidermal layer found at the tip. A space found just behind the pore is surrounded by a special parenchymatous tissue. It is called Epithem. The cells are isodiametric in shape, loosely arranged and enclose a lot of intercellular spaces. An interesting feature is that the xylem elements of vein lets terminate in this tissue. Furthermore some of the parenchymatous cells which surround the xylem elements exhibit structural features characteristic of transfer cells. Such cells contain a large number of finger shaped processes emanating from the cell wall, thus pushing the plasma membrane inwards into a similar pattern. These projections actually increase the surface area of the membranes considerably. Moreover these cells are very active in transporting water and other cellular components. Thus the epithem cells play a significant role in Guttation process.
Under certain conditions like soil flooded with overnight rain water and with high relative humidity of the day atmosphere, the root system of some plants like tomato, potato, etc., absorb excess of water by active uptake. As a result, hydrostatic pressure develops in the root system which actually pushes water upwards. So the water along with other soluble components of the cells is forced out of the xylem elements located into Epithem tissue. As result, the space behind the water stomata gets filled with the water and with more root pressure operating; the liquid is virtually pushed out of the pore, where the stomata do not offer any resistance. Probably transfer cells may also help in the retrieval of minerals and other components from the xylem elements and secreting out along with water. However, it has been speculated that active hydathodes may directly secrete the minerals and organic acids out of the passive stomata. Such active secretion of the above said substances creates a diffusion gradient and water is just withdrawn from the cells into exterior surface so guttation takes place. In spite of the borderline between active and passive mechanisms of guttation is not much, the concepts are attractive.
Lenticels are considered as the breathing pores of the bark. Whichever plants that exhibit secondary growth, produce lenticels in stems as well as in roots. During periderm formation, the cork cambium at certain regions, instead of producing phellum starts producing a group of parenchymatous cells called complementary cells. They are isodiametric, rich in cytoplasm, loosely arranged and thin walled. As the complementary tissue is locally produced, the epidermis is pushed out and finally it breaks open thus exposes the complementary tissue to the external atmosphere.
As the complementary tissue contains so much of intercellular spaces, the atmospheric air diffuses easily into them. Depending upon the relative humidity of atmospheric air, water from complementary cells is lost to intercellular spaces, from which it finds its way into the atmosphere. This process takes place throughout the day and night and there is no way by which it can be stopped. Fortunately the total amount of water lost by this method is again not that significant. It is not uncommon to see, the loss of water through the bark. This happens in spite of suberization of bark cells. However, bark transpiration, along with lenticular transpiration do not cause any serious injury to plants.
Lenticels or breathing pores; www.cas.miamioh.edu