Xylem (Greek, xylos = wood) serves as the main conductive tissue of vascular plants. It is responsible for the supply of water and inorganic dissolved substances. Xylem consists of four types of cells: the roots of seed plants have three main functions: anchoring the plant in the soil, absorbing water and minerals and transporting them upwards, and storing the products of photosynthesis. Some roots are modified to absorb moisture and exchange gases. Most of the roots are underground. However, some plants also have random roots that emerge from the shoot above the ground. Now let`s find out about the different types of meristematic tissues. We know that meristematic tissue is limited to specific regions of a plant. Depending on their location in a plant body, meristematic cells are classified as follows: A tissue is a group of cells whose structure and origin are similar and perform a similar function.
Plant tissue – Plant tissue is a set of similar cells that perform an organized function for the plant. Each plant tissue is specialized for a single purpose and can be combined with other tissues to create organs such as flowers, leaves, stems and roots Epithelial tissue is formed by cells that cover the surfaces of organs, such as the surface of the skin, respiratory tract, surfaces of soft organs, the reproductive system and the inner lining of the digestive tract. Cells that form an epithelial layer are connected by semi-permeable and narrow connections; Therefore, this tissue forms a barrier between the external environment and the organ that covers it. In addition to this protective function, epithelial tissue can also specialize in the function of secretion, excretion and absorption. Epithelial tissue helps protect organs from microorganisms, injury, and fluid loss. The cells in this tissue have the ability to divide and distribute to form new cells (mitosis). Newly formed cells resemble the mother cell, but as they grow, their characteristics change and they differentiate. These cells, present in plant growth areas, help increase the length and width of plants.
In vascular plants, phloem helps in the translocation of organic solutes from the leaf to other parts of the plant. The movement of materials can occur in both directions, unlike Xylem, where only lateral conduction is possible. Sclerenchyma (Greek, sclerosus means hard and enchyme means perfusion) consists of thick-walled dead cells and protoplasm is negligible. These cells have hard and extremely thick secondary walls due to the uniform distribution and high secretion of lignin and have the function of providing mechanical support. They have no intermolecular space between them. The lignin deposit is so thick that the cell walls become strong, rigid and impermeable to water, also known as stone cell or scleride. These tissues are mainly of two types: sclerechymatous fibers and scleroids. The fibrous cells of the sclerenchyma have a narrow lumen and are long, narrow and unicellular. Fibers are elongated cells that are strong and flexible and are often used in ropes.
Scleriates have extremely thick cell walls and are brittle and occur in nutshells and legumes. Connective tissues are fibrous tissues made up of cells separated by a non-living material called an extracellular matrix. This matrix can be liquid or rigid. For example, blood contains plasma as a matrix and the bone matrix is rigid. Connective tissue gives shape to the organs and holds them in place. Blood, bones, tendons, ligaments, fat and areolar tissue are examples of connective tissue. One method of classifying connective tissue is to divide it into three types: fibrous connective tissue, skeletal connective tissue, and liquid connective tissue. In this module, let`s discover these complex tissues. Now let`s discuss these two vascular tissues one by one. LOCATION- This type of tissue is found in the petioles, under the epidermis of leaves and stems. Each plant organ contains all three types of tissues, with different arrangements in each organ. There are also some differences in the arrangement of these tissues between monocots and dicots, as shown below: Figure 2.
Openings called stomata (singular: stoma) allow a plant to absorb carbon dioxide and release oxygen and water vapor. The microscopic electron image with colored scanning (a) shows a closed stoma of a dicot. Each stoma is flanked by two guard cells that regulate its opening and closing (b). Guard cells c) are found in the epidermal cell layer (credit a: change in the work of Louisa Howard, Rippel Electron Microscope Facility, Dartmouth College; Credit b: Change in the work of June Kwak, University of Maryland; Scale bar data by Matt Russell) The cells of the meristematic tissue have a similar structure and have a thin, elastic primary cell wall of cellulose. They are arranged compactly, without intercellular spaces between them. Each cell contains a dense cytoplasm and a prominent nucleus. The dense protoplasm of meristematic cells contains very few vacuoles. Normally, meristematic cells are oval, polygonal or rectangular. The two main forms of plant tissue used in this process are xylem and phloem.
Xylem is a plant tissue specially designed to carry water and nutrients. This plant tissue can come in different forms depending on the species. .