Meristem Network in Plants – Types – Functions and Characteristics
Organs in plants are composed of many cells. The large number of cells is divided into several tissues. A network is a collection of cells with the same shape and function and is bound by material between certain cells to form a unity. The word meristem is an uptake of the Greek word “meristes” which means “to split”.
Meristem network function
Meristem tissue is a tissue in the plant body which contains a group of undifferentiated cells and is active in carrying out cell division. Cell division is a division activity which divides one parent cell into two or more daughter cells. Cell division in this tissue continues so that it continues to increase the number of cells in plants.
Meristem tissue has a very important role in plant growth and development. Meristematic tissue growth can be stimulated or induced by injuring parts of the plant body or through tissue culture. Shoot and cambium meristems are meristem tissue that is very easy to stimulate growth. The tissue formed from this induction process is known as callus. The cells in the callus will continue to divide in vitro.
Characteristics of the Meristem Network
- The cells are prismatic, cubic or rounded.
- Tesusun of cells that are actively dividing.
- Between one cell and another there is no space or cavity, so the network structure becomes dense.
- In cells there are large amounts of protoplasm
- The young cells are still undifferentiated, so they can grow into any tissue.
- Each cell has one or two large cell nuclei.
- The inside of the cell does not contain nutrients this is because the plastids in the meristem tissue are immature. Plastids are dynamic organelles capable of dividing and have a function as a place for the manufacture or storage of an important chemical compound.
- The vacuoles in cells are small or even absent. The vacuole is the organelle in the cell. The vacuole is filled with liquid which contains lots of organic molecules.
With the Meristem network, plants can perform primary growth and secondary growth. Primary growth can occur due to the activity of cell division in the primary meristem tissue. While secondary growth occurs due to the activity of cell division in secondary meristem tissue, the following is an explanation.
Types of Meristem Networks Based on Their Origin
Primary Meristem Network
Primary meristem tissue is a network formed from embryonal cells. This network is found at the end of the stem and the end of the plant stem. Cell division that occurs in primary meristem tissue is the reason for primary growth in plants. Primary growth is the growth in the height of a plant. Primary growth includes longer roots and higher stems.
Secondary Meristem Network
The next meristem network is the secondary meristem. Meristem networks that have matured and cannot develop anymore are the origin of the formation of this meristem network. Such tissue can be found in dicot plants and open seed plants (gymnosperms). Cork cambium and vessel cambium are classified as secondary meristem networks. The function of this network is to cause plants to grow large and wide on their stems and branches. This growth characteristic is not found in monocot plants.
The activities carried out by the secondary meristem network are:
- Adding plant diameter and forming a circle year in the cross section of the plant stem.
- forming a secondary transport bundle network
- Forms pith radius
Promeristem tissue has existed since plants were still in the form of embryos. Promeristem network is the formation of the primary meristem network. Based on Harbelendt’s theory, the promeristem network will develop into three systems,
- Protoderm tissue, namely tissue that will soon develop into the epidermis. Epidermis is the outermost tissue in plants. The epidermis layer is composed of only one layer of cells. In the epidermal cells there are protoplasts even though the number is very small. In the middle of the epidermis there is a large vacuole and no plastids.
- Basic meristem tissue, which then develops into basic tissue or parenchyma tissue. Parenchyma tissue is located next to the epidermal tissue. In contrast to dense meristem tissue, parenchyma tissue tends to be hollow because there is space between one cell and another.
- Procambium, which is a network that will develop into a central cylindrical plant on the stem.
Meristem network types based on location
Lateral Meristem Network
Is a tissue that is in the cork cambium and vessel cambium (vascular cambium). The cork cambium is a part of the cortex that functions in the formation of the phelloderm, while the vessel cambium is the cambium that borders the bark of the wood column. It is the vessel cambium that is what we often refer to as just the cambium. The growth of the cambium inward forms wood, while the outward development of the cambium forms the bark. Both cork cambium and vessel cambium are formed from the existing meristem tissue on the roots and stems.
Intercalar meristem network
The intercalary meristem tissue is a network that plays a role in flower formation and accelerates the growth of stem diameter. This meristem network is located between the secondary meristem network and the primary meristem network.
Apical meristem tissue
Also known as end meristem because of the presence of meristem tissue that is located at the tip of the root, the tip of the main stem and the end of the lateral stem. All meristem tissue that is formed from apical tissue is called primary meristem tissue which promotes primary growth. Because they are located at the tip, the apical meristem produces new cells that make plants grow longer. The growth process in this tissue also produces apical petals and shoots.
According to Schmidt in tunica theory, there are two areas in the apical meristem network, namely the tunica and the corpus.
- The tunica is the outermost part of the growth point and consists of several layers of cells arranged and a collection of cells of relatively small size. The tunica is cleaved laterally and will differentiate into the epidermis.
- The corpus is the central part of the growing point. The corpus area is a large area and is composed of relatively large collections of cells. The corpus divides irregularly in all directions and will differentiate to form tissues that are not epidermal tissue.
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