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- A few layers of cells beneath the epidermis are generally simple permanent tissue.
- All made of one type of cells, which look like each other.
- Such tissues are called simple permanent tissue.
- Various types of tissues- Simple:
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- Parenchyma
- Collenchyma
- Sclerenchyma
- Parenchyma: It is the most common simple permanent tissue.
- It consists of relatively unspecialised cells with thin cell walls.
- They are living cells.
- Collenchyma: The flexibility in plants is due to collenchyma.
- It allows bending of various parts of a plant like tendrils and stems of climbers without breaking.
- It also provides mechanical support.
- Sclerenchyma: It is the tissue which makes the plant hard and stiff.
- For example, the husk of a coconut.
- It is made of sclerenchymatous tissue.
- The cells of this tissue are dead.
- Epidermal cells : It is the outermost layer of cells, Epidermal cells on the aerial parts of the plant often secrete a waxy, water resistant layer on their outer surface.
- It has a protective role to play, cells of epidermal tissue form a continuous layer without intercellular spaces.
- Epidermal cells of the roots, whose function is water absorption, commonly bear long hairlike
- parts that greatly increase the total absorptive surface area.
- In some plants like desert plants, epidermis has a thick waxy coating of cut in (chemical substance with waterproof quality) on its outer surface.
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- Complex tissues are made of more than one type of cells.
- All these cells coordinate to perform a common function.
- Xylem and phloem are examples of such complex tissues
- They are both conducting tissues and constitute a vascular bundle.
- Xylem consists of tracheids, vessels, xylem parenchyma, Xylem fibers.
- Tracheids and vessels are tubular structures.
- This allows them to transport water and minerals vertically.
- The parenchyma stores food.
- Phloem is made up of five types of cells,sieve cells, sieve tubes, companion cells, phloem fibers
- Phloem transports food from leaves to other parts of the plant.
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