What is tissues ( Explain in brief ) ??? What are the types of tissues ??
Your question seems to be incomplete. But assuming your question "in terms of plant tissues" ; here is the answer accordingly.
A tissue can be defined as a group of physically linked cells and associated intercellular substances that is specialized for a particular function or functions.
In a multicellular organism, a group of cells that have similar structure performing a particular function is called a tissue. Plant tissues are of two types --- meristematic and permanent tissues.
- Meristematic tissue: This type of tissue consists of actively dividing cells. The cells are small, polygonal in shape, thin cell wall, dense cytoplasm and large nucleus. Apical meristematic tissues are present at the root tip and shoot tip, help in growing the height of a plant whereas lateral meristematic tissues or cambium are present in the stem so that the plant gains thickness.
- Permanent tissue: The cells of permanent tissue do not divide. It is classified into three types.
Dermal Tissue: This is the outer most protective tissue. It produces waxy, waterproof covering called cuticle.
Ground Tissue: This tissue forms the main plant body and provides mechanical support.There are three types of ground tissues.
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- Parenchyma consists of thin-walled round or oval cells present in roots, stem, leaves, flowers and fruits.
- Collenchyma consists of elongated cells with thick cell wall to provide mechanical support. It is mostly found in non woody plants and veins of leaves.
- Sclerencyma consists of long fiber-like cells within cell walls which contain lignin. This tissue provides mechanical support. The cells are dead when fully formed.
Vascular Tissue: It is also known as conducting tissue. It is of two types.
Xylem is a type of complex tissue which collectively performs the function of transportation of water and mineral salts from root to leaves in plants. The tissues of xylem are derived from primary meristem. The xylem is usually made up of four types of cells: tracheids, vessels, fibers and parenchyma.
Phloem is a type of complex tissue which is meant for translocation of food materials from leaves to different parts of a plant. It is derived from procambium (primary phloem) and vascular cambium (secondary phloem). The phloem is made up of sieve tubes, companion cells, phloem parenchyma and fibers.
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