In the article we will talk about the anatomy of plants. We will consider this topic in detail and try to understand the issue. Plants surround us from birth, so it is useful to learn something new about them.
What is it about?
Plant anatomy is a branch of botany that studies the internal and external structure of plants. The main object of this science is vascular plants, which have a special conductive tissue, it is also a xylem. This group includes horsetails, gymnosperms and flowering plants, and lacunae.
History
For the first time, the anatomy of plants was affected in the writings of Theophrastus back in the 5th century BC. He already described important structural parts, namely the stem, branches, flowers, roots and fruits. This author believed that root, core and wood are the main plant tissues. In principle, we can say that such ideas have survived to our time.
Middle Ages
In the Middle Ages and after them, studies of plant anatomy continued. So, in 1665, R. Hook, thanks to a microscope, discovered a cell. This was a major breakthrough and allowed us to explore new horizons in this matter. N. Grew in 1682 wrote a work in which he described in detail the microscopic structure of many plant structures. In his work, he illustrated all the facts. Highlighted some difficult points regarding weaving fabrics. In 1831, H. von Moll studied the conducting bundles in the roots, stem, and leaves. Two years later, C. Sanio was able to find out the origin of the Cambyses. Thus, he showed that new phloem and xylem cylinders appear annually. Note that the phloem is a tissue that can transport organic matter in plants. In 1877, Anton de Bari published his work entitled "Comparative anatomy of the autonomic organs of the bride and groom and ferns." It was a classic work on plant anatomy. But here he ordered all the material collected by that time and outlined it in detail.
In the last century, the development of anatomy and morphology of plants went very quickly along with other industries. It was closely associated with great progress in all biological sciences, which was due to the creation of the latest and universal research methods.
Anatomy
What is plant anatomy? Botanists believe that this is a subsection of their science. She does not study the structure of plants as a whole, but only at the level of cells and tissues, as well as the development and location of tissues in certain organs. Also included is the concept of plant histology, which involves the study of the structure, development and functioning of their tissues.
Anatomy as a whole is an integral part of morphology, but in a narrow sense it concentrates on studying the structure and formation of plants at the macroscopic level. This discipline is very closely intertwined with plant physiology - a branch of botany that is responsible for the laws of processes in living organisms.
Note that specifically the study of plant cells later stood out as an independent science - cytology.
Initially, the anatomy of plants was the same as morphology. However, in the middle of the last century, serious discoveries occurred that allowed anatomy to stand out in a separate branch of knowledge. Information from this area is actively used in crop production and taxonomy.
Morphology
Morphology is a branch of botany that studies the laws of the structure and morphogenesis of plants. In this case, organisms are considered in two areas: evolutionary-historical and individual (ontogenesis).
An important task of this direction is to describe and name all the organs and tissues of the plant. Another task of morphology lies in the study of individual processes to establish the features of morphogenesis.
Morphology is conditionally divided into micro and macro levels. Micromorphology includes those areas of knowledge that study organisms using a microscope (cytology, embryology, anatomy, histology). Macromorphology includes sections that study the external structure of plants as a whole. In this case, the microscopy methods are completely non-basic.
Plant leaf anatomy
The leaf consists of the epidermis, vein and mesophyll. The epidermis is a layer of cells that protects the plant from various adverse effects and excessive evaporation of water. Sometimes the epidermis layer is additionally covered with cuticle. Mesophyll is an internal tissue whose essence lies in photosynthesis. The network of veins is formed due to the conductive tissue. It consists of sieve tubes and vessels that are needed to move salts, mechanical elements, and sugars.
The stomata is a group of cells that is located on the lower surface of the leaves. Thanks to them, gas exchange and evaporation of excess water occurs.
We examined the anatomy of higher plants, and now pay attention to morphology. Leaves are composed of petiole, stipules and lobes. By the way, the place where the stem adjoins the petiole is called the vagina of the plant.
The main types of leaves
Having examined the anatomy and morphology of higher plants, let us dwell on certain types of leaves. They are fern, coniferous, angiosperms, plauniform and wrapping. Thus, we understand that leaves are classified by the type of plant in which they are most pronounced.
Stem
Finishing studying the anatomy of plant organs, let's talk about the stem. It represents the axial part on which the leaves and reproductive organs are located. For aboveground formations, the stem is a support, which ensures the flow of not only water, but also organic substances into different zones of the plant. If the stems are green, like cacti, then they are capable of photosynthesis. An important task of this body is that it is able to accumulate in itself beneficial substances that some plants need for vegetative propagation.
As we said above, the upper part of the stem is covered with a special bag. It consists of many dividing cells that grow on top of each other. It is interesting that the rudiments of leaves are formed here. They overlap each other, and then stretch and turn into internodes. Note that this “cap” of the stem, or its apical meristem, has been studied as thoroughly as possible, unlike other zones. From the stela depart vascular bundles, which are called leaf traces. By the way, between them the phloem and xylem are not formed. It is noticed that, evolving, the plants lengthen the height of leaf traces, thus turning the leaf stela into a cylinder entangled in vascular bundles.
We examined the objects of study of the ecological anatomy of plants and realized how difficult the plant, at first glance seeming so primitive. Anatomy and morphology are necessary not only for the theory of botany, but also for practical purposes. So, knowing this topic perfectly, you can easily collect and properly prepare medicinal herbs.
Cell
Note that despite the fact that the external variety of plants is very large and immense, their cells are largely similar. In order to holistically consider the internal structure of the body, you first need to learn about the organization of cells and their types. So what is a cell? It is known that it consists of protoplasm, which is surrounded by a rigid membrane, namely the cell wall. It is formed from cellulose and pectin, which protoplasm secretes. Many cells, after they stop growing, lay on their inner side, that is, on the primary wall of the cell, a secondary wall.
But what is protoplasm? This is a common mixture of sugars, fats, water, acids, proteins, salts and many more other substances. Thanks to the reasonable distribution of all of them in parts of the cell, the plant can perform some vital functions. If we consider the protoplasm under a microscope, we can see that it is divided into the nucleus and cytoplasm. In the latter are plastids. The nucleus is a rounded body, which is surrounded by a double membrane. It contains genetic material. The nucleus controls the chemical processes in the cell and influences them. Cytoplasm is a substance that contains a huge number of intricate structures characteristic only of plants. Note that colorless plastids, or leukoplasts, as well as nutrients are necessary to ensure the life of the plant. In green plastids, or chloroplasts, photosynthesis of sugars occurs. It is worth saying that old cells have a slightly different structure. So, their central part, which is surrounded by a membrane, is adjacent to the cell wall. Note that the origin of any type of plant cell comes precisely from those that we examined in detail above.
Fabrics
The anatomy and morphology of plants can be considered in the context of tissues. Plant organisms are divided into some zones, the features of which are largely determined by the type and arrangement of cells. Such areas are called tissues. If we rely on the classical definition, we can understand that tissues are classified by structure, origin, and function. Note that functions can sometimes coincide. They can be limited from each other and not always homogeneous. Because of this, it is very difficult to classify tissues, therefore, in the modern world, when it comes to this, they talk about specifically named plants. We can say that in this case, plants are considered in a topographical sense.
When examining it with a cross section of the root and stem from the periphery to the center, such important zones as the epidermis, the conducting cylinder, the root and the central core are usually distinguished.
Root
Consideration of the anatomy of the plant root will begin with the definition. So this is the part of the plant that has no foliage. It absorbs water and nutrients from the soil or any other medium. The root can hold moisture and organic matter in the substrate. Moreover, for some plants, it is the main storage organ. This is observed in beets, carrots.
If we consider the root, then it clearly distinguishes such zones as steles and bark. They grow and develop due to the division and diversity of apical meristem cells. This is the name of some groups of cells that retain the ability to divide and can reproduce non-dividing cells. Thanks to this system, the root cover is strengthened, which fixes the end of the root, thus protecting it from various damage during immersion in the soil. It should be noted that the growth, division and differentiation of cells is a natural process, thanks to which the maturation and extension zones can be noted vertically. At this level, it is possible to trace in sufficient detail the stages of development of the epidermis, stela and bark. Above the stretch zone, by the way, there are elongated outgrowths in the shape of a cylinder, which are called root hairs. Thanks to them, the absorption capacity is significantly increased.
Stele
Indeed, the amazing science of botany. The morphology and anatomy of plants open up a completely different view of the whole plant world known to us. As we already know, the constituent stela are xylem and phloem. The first is closest to the center. We also note that most often the core in the roots is absent, but even if it occurs, it occurs in monocotyledonous plants more often than in dicotyledons. Lateral stems form in the pericycle and thus make their way through the bark. If the root can grow in breadth, then between the phloem and xylem a secondary layer is formed - cambium. If there is increased growth in thickness, then the cortex and epidermis most often die. At the same time, cork cambium is formed in the pericycle, which is a protective layer for the root, that is, a “cork”.