प्लांट टिश्यू

Plant Tissue

Plants are complex organisms with various tissue systems, each composed of cells that carry out specific functions. These tissue systems can be broadly classified into meristematic tissue and permanent (or non-meristematic) tissue. Meristematic tissue is found in meristems, which are regions of continuous cell division and growth in plants, while permanent tissue is composed of cells that are no longer actively dividing.

Meristematic Tissue

Meristematic tissue cells are either undifferentiated or incompletely differentiated, and they continue to divide and contribute to the growth of the plant. There are three types of meristems based on their location in the plant: apical meristems, lateral meristems, and intercalary meristems. Apical meristems are located at the tips of stems and roots, enabling a plant to extend in length. Lateral meristems facilitate growth in thickness or girth in a maturing plant. Intercalary meristems occur only in monocots, at the bases of leaf blades and at nodes, where leaves attach to a stem.

Permanent Tissue

Permanent tissue consists of plant cells that are no longer actively dividing. These cells differentiate into three main types: dermal, vascular, and ground tissue.

Dermal Tissue

Dermal tissue covers and protects the plant. In woody plants, this tissue forms a tough, waterproof outer layer known as bark. The epidermis, a single layer of cells, is the most numerous and least differentiated of the cells in dermal tissue. It covers and protects the underlying tissue in stems and leaves. The epidermis of a leaf contains openings known as stomata, through which gas exchange takes place, and specialized cells called guard cells regulate the opening and closing of the stomata.

Ground Tissue

Ground tissue serves as a site for photosynthesis, provides a supporting matrix for the vascular tissue, and helps to store water and sugars. This tissue is diverse and has various functions. For example, collenchyma cells are long and fibrous, providing support for non-woody parts of the plant. Parenchyma cells store molecules such as starch and photosynthesize. Sclerenchyma cells support the plant and assist in storing water and sugars.

Vascular Tissue

Vascular tissue transports water, minerals, and sugars to different parts of the plant. It is composed of two specialized conducting tissues: xylem and phloem. Xylem tissue transports water and nutrients from the roots to different parts of the plant, and includes vessel elements and tracheids, which conduct water, and xylem parenchyma. Phloem tissue, which transports organic compounds from the site of photosynthesis to other parts of the plant, consists of sieve cells, companion cells, phloem parenchyma, and phloem fibers.

In summary, plant tissues are essential for the growth, development, and survival of plants. Meristematic tissue is responsible for growth and cell division, while permanent tissue, including dermal, vascular, and ground tissue, carries out various specialized functions such as protection, support, and transportation.