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's good 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, also known as xylem. This group includes horsetails, gymnosperms and flowering plants and club mosses.
History
For the first time, plant anatomy was touched upon in the writings of Theophrastus as early as the 5th century BC. He already then described important structural parts, namely the stem, branches, flowers, roots and fruits. This author believed that the root, pith 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, research into plant anatomy continued. So, in 1665, R. Hooke, thanks to a microscope, discovered a cell. This was a big breakthrough and allowed to explore newhorizons in this matter. N. Gru wrote a work in 1682, in which he described in detail the microscopic structure of many plant structures. In his work, he illustrated all the facts. Illuminated some difficult points regarding the weaving of fabrics. In 1831, H. von Mol investigated vascular bundles in roots, stems, and leaves. Two years later, K. Sanio was able to find out the origin of the Cambia. Thus, he showed that new cylinders of phloem and xylem appear annually. Note that the phloem is a tissue that can transport organic substances in plants. In 1877, Anton de Bary published his work en titled Comparative Anatomy of the Vegetative Organs of Phenogamous and Ferns. It was a classic work on plant anatomy. But here he ordered all the material collected by that time and presented it in detail.
In the last century, the development of anatomy and morphology of plants went very quickly along with other branches. 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 consider this to be a subsection of their science. She studies the structure of plants not as a whole, but only at the level of cells and tissues, as well as the development and location of tissues in certain organs. This also includes 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 partmorphology, but in a narrow sense it concentrates on the study of 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 patterns of processes occurring in living organisms.
Note that specifically the study of plant cells later emerged as an independent science - cytology.
Initially, plant anatomy was the same as morphology. However, in the middle of the last century, serious discoveries occurred that allowed anatomy to stand out as 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 structure and morphogenesis of plants. At the same time, organisms are considered in two areas: evolutionary-historical and individual (ontogeny).
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 conventionally 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 dealing with the study of the external structure of plants as a whole. In this case, microscopy methods are completelybasic.
Anatomy of a plant leaf
The leaf consists of epidermis, vein and mesophyll. The epidermis is a layer of cells that protects the plant from various adverse effects and excessive water evaporation. Sometimes the layer of the epidermis is additionally covered with a cuticle. Mesophyll is an internal tissue, the essence of which is photosynthesis. The network of veins is formed due to conductive tissue. It consists of sieve tubes and vessels that are needed to move s alts, mechanical elements and sugars.
Stomata is a group of cells that is located on the lower surface of the leaves. Thanks to them, gas exchange occurs and excess water evaporates.
We examined the anatomy of higher plants, and now we will pay attention to morphology. Leaves consist of petiole, stipules and lobes. By the way, the place where the stem adjoins the petiole is called the plant's vagina.
Basic 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, lycopsids and wrappers. Thus, we understand that the leaves are classified according to the type of plant in which they are most pronounced.
Stem
Finishing the study of the anatomy of plant organs, let's talk about the stem. It is the axial part on which the leaves and reproductive organs are located. For above-ground formations, the stem is a support that ensures the flow of not only water, but also organic substances into different zones.plants. If the stems are green, like those of cacti, then they are capable of photosynthesis. An important task of this organ is that it is able to accumulate useful substances that some plants need for vegetative reproduction.
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 in as much detail as possible, in contrast to other zones. Vascular bundles, which are called leaf traces, depart from the stele. By the way, phloem and xylem do not form between them. It has been observed that, while evolving, plants lengthen the height of leaf traces, thus turning the leaf stele into a cylinder entangled in vascular bundles.
We looked at the objects of study of the ecological anatomy of plants and realized how complex a plant that at first glance seems 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.
Cage
Note that despite the fact that the external diversity 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 ofprotoplasm, which is surrounded by a rigid shell, namely the cell wall. It is formed from cellulose and pectin substances secreted by protoplasm. Many cells, after they stop growing, lay a secondary wall on their inner side, that is, on the primary wall of the cell.
What is protoplasm? It is a common mixture of sugars, fats, water, acids, proteins, s alts and many other substances. It is thanks to the reasonable distribution of all of them in parts of the cell that the plant can perform some vital functions. If we examine the protoplasm under a microscope, we can see that it is divided into the nucleus and cytoplasm. The latter contains plastids. The nucleus is a round body 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 that are 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 plant cell types comes precisely from those that we examined in detail above.
Fabrics
Anatomy and morphology of plantscan be viewed in terms of tissue. Plant organisms are divided into some zones, the features of which are largely determined by the type and location of cells. Such areas are called tissues. If we rely on the classical definition, then we can understand that tissues are classified according to structure, origin, and functions. Note that functions may sometimes overlap. They can be limited from each other and are not always homogeneous. Because of this, it is very difficult to classify tissues, which is why 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 in a cross section of the root and stem from the periphery to the center, such important zones as the epidermis, the conductive cylinder, the root and the central core are usually distinguished.
Root
Consideration of the anatomy of the root of a plant, let's start with a definition. So that's the part of the plant that doesn't have leaves. It absorbs water and nutrients from the soil or any other medium. The root can retain moisture and organic matter in the substrate. At the same time, for some plants, it is the main storage organ. This is observed in beets, carrots.
If we consider the root, then such zones as stele and bark are clearly distinguished in it. They grow and develop due to the division and diversity of the cells of the apical meristem. 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 cap is strengthened, which fixes the end of the root, thus protecting it from various damages during immersion in the soil. Note that the growth, division and differentiation of cells is a natural process, due to which the zones of maturation and stretching can be marked vertically. At this level one can trace the stages of development of the epidermis, stele, and cortex in some detail. Above the stretch zone, by the way, there are elongated outgrowths in the form of a cylinder, which are called root hairs. Thanks to them, the suction capacity is greatly increased.
Stela
Really, the amazing science of botany. The morphology and anatomy of plants open up a completely different view of the entire plant world known to us. As we already know, the components of the stele are xylem and phloem. The first is located closest to the center. We also note that most often the core is absent in the roots, but even if it occurs, it occurs in monocots more often than in dicots. Lateral stems form at the pericycle and thus push their way through the bark. If the root can grow in breadth, then a secondary layer, the cambium, is formed between the phloem and xylem. If there is an increased growth in thickness, then the bark and epidermis most often die off. At the same time, a cork cambium is formed in the pericycle, which is a protective layer for the root, that is, a “cork”.
