Table of Contents
The definition of plant tissues refers to the group of cells that are conglomerates, given that they are permanently joined forming large laminar and solid groups. These groups of cells have similar characteristics in terms of their functions and their forms. It is worth mentioning that such tissues are fused with the purpose of being able to continuously develop these same functions. These tissues constitute cells called eukaryotes,which are of plant origin. These are derived as a result of cells that come from the embryo of a seed that is formed after the fertilization of plants.
Plant tissues are what make up most plants. These are living cells are responsible for all development processes, which can be photosynthesis, respiration, storage of various substances; as well as the growth and repair phases to replace dead cells. These fabrics provide the resistance and support required for the plants, which in turn form drivers for the raw brute.
Types of plant tissues
We have been able to identify a great variety of types of plant tissues, which have been classified according to the functions they perform . The main functions are described below:
- The protective fabrics, as its name implies, serve to protect the plant. This work is done through the formation of external layers, which help to protect and avoid damage by external agents. This layer is formed by epidermal tissue and also suberous tissue.
- The conductive tissues are those that are created from various types of cells; and for that reason they are considered to be a more complex fabric. In most cases, these come from meristematic cells. Mainly, there are two types of conductive tissues: the xylem and the phloem. The latter are part of both the vascular system; as well as drivers in vegetables.
- The growth tissues . They are also called meristems. These are a series of young cells, which are continuously in the process of division, which is called mitosis. These cells are what help the formation of plants. Their nuclei are large and there is a large amount of cytoplasm in them.
- The parenchymatic tissues are responsible for nourishing. They are located in most plant organisms. These are responsible for filling spaces that are free in other organs, as well as in the tissues of the same plant so that there are various categories. These are the ones that intervene in the process of photosynthesis .
- The support tissues are those that are made from cells, which can be seen in their walls a greater thickness, which helps them have greater mechanical resistance. These in their functions share, but at the same time they differ in relation to its texture and the structure of cell walls.
- The secretory tissues are those that have different structures. However, the common characteristic they possess is their ability to store, and also to segregate different substances through a series of cavities, both external and internal. These are classified according to the place where they are located in the plant.
- The meristematic tissuesintervene in the process of plant growth. Such tissues help to develop both diametrically and longitudinally. These cells have the ability to multiply and differentiate each other.
We have described the main tissues that make up plant organisms. However, on this subject we want to give some additional explanations in the following paragraphs.
The so-called parenchymal tissues are those that make up most of the body of a plant. These are tissues that are formed by living cells at the stage of maturity. In turn, it happens that these cells possess the ability to subdivide. It is important not to confuse these tissues with the conductive vessels that accompany the parenchyma.
These tissues intervene in the growth process that originates from the felógeno and the cambial activity, located in the marrow and in the bark of the stems and roots. In the case of flowers in the mesophile . In the case of the fruits, this happens in the fleshy areas. Finally, in the case of the seeds in the endosperm . It happens that the parenchyma is formed by living cells whose physiology and morphology varies in relation to the type of activity that it performs. Therefore, it is a very heterogeneous type of plant tissue.
These tissues fulfill some of the most essential functions of the plant. Among these functions we can mention the photosynthesis and the storage of different types of reserve substances among which are water. These cells are part of the xylem and the phloem . It also happens that they intervene in the translocation of water and mineral salts. Conductive elements.
The parenchymal cells are characterized by having the ability to resume meristematic activity, always depending on the degree of specialization of them. These cells have a polyhedral shape and are considerably larger. In addition, it happens that sometimes its shape lengthens in the primary cellulose walls . Also, it happens that sometimes they become thicker since there are numerous pits, as it happens in seeds where it is observed in the endosperm . The cellular content is related to the physiological activity. According to the structure and its physiological activity, these are classified as follows:
1. The fundamental parenchymal tissuesare the least specialized. They are characterized because their primary walls are thin and are among other tissues of the medullary region and the cortex. They retain their ability to divide by mens of mitosis, in the stage of maturity. It is worth mentioning that this capacity allows a single cell to regenerate completely in an in vitro culture.
- 2. Chlorophilic parenchymal tissues are cells that are found in varying amounts of chloroplasts. There are two types. The first of these are the palisade cells , which are more elongated and have abundant chloroplasts, as well as the intercellular spaces in smaller quantities and are located in the leaves. The second are the lacunae cells , which have an irregular shape and a small amount of chloroplasts, and the intercellular spaces are more abundant. The latter allows the diffusion of the gases to pass through the leaf structure. They are placed towards the back of the leaves.
3. The reserve parenchymal tissues are responsible for storing different types of reserve substances, such as proteins, lipids and starch . Commonly found in the roots, but it is also possible to find them in the seeds, tubers, bulbs and rhizomes.
4. The aquifer parenchymatous tissues , as the name implies, are responsible for storing water . They are very frequent, especially found in succulents. The mucilages found in the vacuoles, being the structures that allow it to be possible to retain larger amounts of water. The parenchymal tissues aeríferos are usually found in aquatic plants in the intercellular spaces. Its presence allows aeration; as well as it represents an essential fabric to float and is a supporting element. The system of spaces depends on the irregular or star shape of these cells.
The epidermal tissue is that which covers most of the outer surfaces of herbaceous plants . These are formed from epidermal cells, which are joined together by strong bonds, and in turn secrete a layer known as the cuticle. This layer is formed with wax and cutin, this pair of substances being those that help to keep the water without loss to the plant. In the epidermal tissue can be observed various types of specializations, such as stomata and trichomes.
The epidermal tissue is found throughout the body of a vegetable. That is why it has been identified that the function of this fabric is to protect from various types of external agents, which can trigger mechanical damage, thus protecting against adverse environmental conditions. Also, they are structures that fulfill other functions, such as helping to offer greater mechanical support. On the other hand, in terms of the root system is a tissue that is responsible for the process of absorption of nutrients and water. This is possible because they have the distinction of having thinner cell membranes and absorbent hairs.
The cuticle layer can vary in relation to the thickness of each plant species. Sometimes, it can be made up of only one type of cells, in this case they are called uniestratified . Conversely, if it is constituted by several types of cells it is called multilayered . The epidermal tissue, in comparison with the other types of plant tissues, is much more complex because it is made up of not only epidermal cells; but also stomatal, trichome and buliform.
In some varieties of herbaceous plants, the epidermis is the same that is maintained throughout the life of the plant. However, in the case of plant species of woody type this tissue will be replaced at some point by another secondary protection, called peridermis . This replacement tissue is made up of felogen, suber and felodermis cells . The suber (or cork) is composed of dead cells; generally on suberified walls. In the case of felodermis, these are made up of parenchymal cells. On the other hand, it happens that the felógeno originates on the outside of the cork until the inside of the felodermis.
Vegetable tissues outline
From the first divisions of the zygote, it happens that the apical pole first forms ; which is the origin of the stem along with the buds of the first leaves of the plant. From it, the formation of the primary root begins . Eventually, with the development of the embryo specialization increases, that is, the ability to divide and grow; which is restricted to the ends of the apical pole of the stem; as well as the root.
It is a part of the plant consisting of meristematic tissues. These cells are grouped to form mature tissues, which have specific functions. These are differentiated cells that have lost the ability to divide.
In the embryonic phase, it can be observed that the vertical axis that starts from the apical pole will result in the formation of a stem with leaves; while the basal pole is the origin of the root. The specialized tissues that intervene in the growth process are divided indefinitely, always in order to maintain this same process throughout the life of the plant.
The different types of plant tissues responsible for primary growth do so longitudinally. For its part, the tissues responsible for secondary growth do so in relation to thickness. All plant tissues constitute an adult plant and differ from the meristematic tissue.
The different types of fabrics are classified according to the position or location in which they are found in the plant. Likewise, they can be classified by their intervention in the development of growth. The primary tissues are the apical ones , while the secondary tissues are the lateral ones. The so-called meristemoid tissues are found in small areas of cells, which are in a continuous process of division. It is worth saying that while this occurs, differentiated structures are produced; which can be stomata or hair. These are structures that are characterized by inducing the division of cells that are close to them.