On our planet there are more than four hundred species of various plants, and all of them perform various functions. We, along with other animals, consume them for food, but with the difference that we subject plants to various types of processing - we cook, fry, stew, and preserve; we make clothes, medicines, furniture from them; they supply all living things with oxygen. For many years, scientists have been studying different species, their properties, working on the selection of new species that are more resistant to current environmental and climate conditions, and are working on the conservation of endangered species, studying utility and other things that are important both for humans and the environment as a whole. Specifically, a topic will now be touched upon that reveals such concepts as the structure of the root system, its types and functions.
What is a plant organ?
On the organs, parts of any plant are distributed by function and structure. The principles of separation are the same as in animals, including humans. The ear and liver have different forms and functions, which is why they are named differently. Same thing with leaves and roots. If we talk about higher plants, then the separation of organs goes into two large groups, vegetative (those that serve for growth and nutrition) and reproductive (responsible for the reproduction of their own kind). Any type of root system belongs to the autonomic organs.
The concept of the root and its functions
The root is the axial organ of the plant. First of all, it fixes plants in the soil. It also performs the function of “nutrition”, and now we are talking about such a part of the root as hairs. That is, the answer to the question of what function the root hairs perform is precisely the absorption from the soil of water and minerals necessary for the full life of the plant. Also, the root system is capable of producing various substances, such as growth hormone, or various alkaloids necessary for the entire plant. These substances can move up the plant stem, and can accumulate in the root system itself. It can also work as a pantry - something like a cellar for useful nutrients. Plants with such a root are called root crops.
We all know carrots, beets, radishes, which are precisely these root crops. What else the root system is capable of is the interaction with the "neighbors" in a particular place of growth. So, symbiosis is possible with other plants, with fungi or even with microorganisms, and almost any type of root system is capable of this. In addition, vegetative propagation may also be related to root functions. Its advantage is that for the emergence of a new plant does not require a partner, as in the case of sexual reproduction.
Vegetative propagation - what is the point
This reproduction of their own kind can happen even with the help of an ordinary leaflet. Once in favorable conditions, he can shoot, and, for example, a new begonia will be born. The willow branch, breaking away from the tree, can also catch in the ground and take root. The roots are capable of the same thing. In some plants, buds can form on the rhizome, from which new, full and identical individuals grow, or tubers form. The most striking example, which relates to the latter case, is potato - a guest from America who has taken root so well in our conditions. So, the tubers that form on the roots of this plant and are actively consumed by us at the same time are used for planting and growing new potato bushes, and, accordingly, new tubers. Sprouted potatoes, even a part of them that have at least one sprout, can give life to a new, full-fledged potato bush, no different from its “mother”. And good conditions will be conducive to better development of the bush and even increase yield. All root farmers know what function root hairs do, and therefore they use such fertilizers and the method of processing the soil, after which they remove high yields of high-quality natural products. Of course, there still a lot of things depend on weather conditions during the growth period, but this is another matter. Let's get back to vegetative propagation.
So, such reproduction is actively used in horticulture and agriculture. But along with the benefits, we can recall the harm. So, weed talk. For the cultural economy, there is such a problem as wheat grass. The rhizomes of this plant are huge, and if damaged, they are easily restored, turning into a new plant. For example, if one rhizome is split in shallow plowing into four, four new weeds will soon grow. This is bad for a person, namely for the owner of the site, who wants to grow a lot of different vegetables on it, but instead gets a wheat grass crop. But for the plant itself, such an ability is a huge plus.
An interesting case when rhizomes have sleeping kidneys. This often applies to trees. When the main plant lives and thrives, these buds are as if in a coma. They are, they are alive, but there is no development. But if, let’s say, a tree is cut down, then these buds are rapidly activated and turn over time into young plants of the same species. Oak, linden, and birch trees have such buds.
What are the main root types?
There are three types of roots. The main one develops from the germinal seed. Side roots that are able to branch out from it. There are also subordinate roots. They can appear on top of the plant, on the stems or leaves. Together, the root types make up the whole root system. According to the characteristics of these types, the root system is distributed by type.
Types of root systems
If the plant has a well-defined main root, then such a root system is called the core.
What does “well defined” mean? This means that it is much thicker and longer than all the other roots that diverge from it. Such a root system is characteristic of dicotyledonous plants. If the main root of the plant is not expressed, then such a root system is called fibrous.
The main root may be absent or not different from the rest.
Each root can be divided into several zones, which is responsible for a specific function.
Four distinct zones characteristic of young root
The first zone is characterized by cells of the apical meristem. This is the division zone, or root cap. The length of the cover reaches one millimeter.
The second zone is the zone of growth or extension. It is thanks to the growth of cells of this part, only a few millimeters long, that the main elongation of the root occurs.
The third zone is the absorption zone, or the zone of root hairs. There is a maximum of them - the number is measured in hundreds of pieces per millimeter square, and they constantly absorb nutrients from the earth, which go further into the fourth root zone - into the conduction zone, where there are no root hairs anymore, and full-fledged powerful (on a scale individual plants) lateral roots.
Any types of root systems have such zones on young roots. There are no clear sections between the zones; they all smoothly pass into each other.
Interesting about young root zones
The root cap is also called caliptra. Its cells live no more than nine days, and then die, exfoliated from the root. In this case, abundant secretion of mucus occurs, which facilitates the root to grow further - deeper or wider, it does not matter.
It is the stretch zone that pushes the root further into the ground. When the cells of this zone accumulate water, they stretch in length, and this happens until the cells finally coarsen and they enter the absorption zone. By the way, this zone is actually transparent in appearance.
In the place where there was once a stretch zone, hairs begin to form. But above, in front of the venue, they at the same time begin to die. So the absorption zone moves after pushing the root into the soil. The number of hairs per square millimeter is calculated in hundreds.
The absorption zone is the most important part of the root for plant life
The root hairs of plants, as mentioned earlier, absorb water from the soil, minerals dissolved in water, which are necessary for full growth. Therefore, we will dwell on this root zone and consider it in more detail.
What is a root hair?
What function do root hairs perform, we have already roughly figured out. Now it’s worthwhile to understand how this happens, due to what structural features of these very hairs, the absorption of substances from the soil is possible. Any root hair, the description of which, in principle, can take only three lines, is actually very important.
The length of such a hair is very small and lies in the range of 0.1-8 mm, according to other sources - 0.06-10 mm. The diameter of the hair can range from five to seventy micrometers. If we talk about the structure of root hairs, then these are, for the most part, elongated cells of the root skin. Almost all of this cell is a vacuole around which there is a thin layer of cytoplasm, and which contains the nucleus of the cell. It is located in the cytoplasm so that it is at the top of the hair.
The structure of the suction zone
If we make a cross-section, we will see the presence of three main sections - this is the central cylinder, the cortex and the outer coating in the form of a thin-walled skin on which root hairs are formed. The absorption zone begins with the fact that the skin cells are covered with mucus, to which the soil adheres. Thus, the absorption of vital substances from the soil is facilitated. Next comes the layer of bark, which acts as the protector of the central cylinder, the creator of vitamin compounds and the keeper of reserve substances, most often - starch. The central cylinder is a conductive tissue along which all elements absorbed and created in the previous two sections move up into the plant.
Absorption and excretion
To understand how root hairs provide the absorption of substances from the soil, it is worth mentioning two features. First, the cells of the hair are capable of enveloping a particle of the earth and literally grow together with it. The second - for better absorption, hairs secrete various acids (oxalic, malic, carbonic). These two features are key in the process of plant nutrition.
Dimensions of the root hair system
We figured out what function root hairs perform. But here is the question: "How are such scanty (recall, the size of one root hair - 0.1-8 mm) shoots capable of feeding, for example, a huge birch?" The answer is simple. They do not take in size, but in quantity. If we talk about the rye shoot, which is four months old, he has about ... 14 billion root hairs. This is just ten thousand kilometers of thread, which absorbs everything and everything in its path, with an absorption area, by the way, in the region of four hundred square meters. What about huge plants, the root system of which spreads many meters around the trunk in the upper layers of the earth (for example, walnut roots extend up to twenty meters around them), or those that take root deep into the ground (the same Greek walnut can penetrate to a depth of six to seven meters).
The walnut tree, given as an example, fixes the soil well and protects it from landslides precisely because of its root system. A person uses these features to preserve areas at risk of a landslide, and it is also unreasonable for the same person to cut down forests that keep their mountainous roots.
Root hair lifespan
The formation of such root organs occurs relatively quickly. Sometimes for this, something about a day is enough - for each plant, the timing is different. But the hairs live for ten to twenty days. They are gradually replaced by new ones growing after the root moves in the soil at the place where the root growth zone has become rougher, moving further behind the root cover.
Thus, we learned what function root hairs do, without delving too deep into the terminology of biological sciences that is difficult for simple ears and, in addition, simultaneously examining individual features of the root system as a whole.