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Lab 10 : Plant tissues

Lab 10 : Plant tissues. Tissues can be classified into : Meristematic tissues Permanent tissues. Plant tissues. Meristematic tissue characteristics:. Small ,thin – walled cells. No central vacuole. No specialized features. Ability to divide. Found in young tissues of embryo.

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Lab 10 : Plant tissues

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  1. Lab 10 : Plant tissues

  2. Tissues can be classified into : Meristematic tissues Permanent tissues Plant tissues

  3. Meristematic tissue characteristics: • Small ,thin – walled cells. • No central vacuole. • No specialized features. • Ability to divide. • Found in young tissues of embryo. • Types of meristematic tissues: - Primary meristems : apical meristems ( near tips of root and stems). - Secondary meristems : vascular cambium & cork cambium.

  4. Meristematic tissues

  5. Permanent tissue characteristics: • Derived from meristems. • Mature ,differentiated tissue.

  6. 1. Epidermis : • Location : outermost layer , covering plant parts. • Function : desiccation resistance , gas exchange, protection against • herbivores and pathogens. • Cell types of the epidermis: • Pavement cells : secrete a water-repellent cuticle that reduces water • loss and pathogen invasion. • Guard cells : form (stomata ثغور) for gas change.

  7. Epidermis

  8. Pavement cells cuticle 8

  9. Guard cells stomata

  10. 2. Ground tissue: • Parenchyma: is the main ground substance of the plant • body in which other important tissues are present. • Types : • - Aerenchyma : parenchyma with air spaces. • - Chlorenchyma : parenchyma full of chloroplasts. • Locations : • - cortex of roots and stems. • - pith of roots and stems. • - mesophyll of leaf. • Function : • - storage , respiration, photosynthesis

  11. Characteristics: • Mature ,living cells. • May become active to divide. • Polyhedral in shape. • It has spaces between cells

  12. Collenchyma: Characteristics: - living at maturity. - they have much thicker cell walls. - the thickening of the walls may be in the angle or on the tangential. Function: - provide support. Location : - the outer part of cortex

  13. Sclerenchyma: • It form of : • Fibers : long slender cells occur in vascular bundle • ( xylem fibers , phloem fibers, bundle sheath) • - Sclereids : have variable shapes , found in seed coats. • Characteristic: • - thick-walled lignified , non-living and lack protoplast. • Function : • - support and protection

  14. Ground tissues Sclerenchyma (Fibers) Sclereids 14

  15. Ground tissues Parenchyma Collenchyma

  16. 3. Vascular tissues : include xylemالخشب and phloem اللحاء 1. xylem : -is the principle of water conducting tissues in vascular plants. - It may also act as a mechanical support to different plant organs. Primary xylem: is the xylem formed during primary growth from procambium. It includes Protoxylem and Metaxylem. Secondary xylem: is the xylem formed during secondary growth from vascular cambium. Xylem is a complex tissue formed from of: 1. vascular elements : - vessels - Tracheid القصيبات الوعائية 2. xylem fibers 3. xylem parenchyma

  17. 2. Phloem- is the principle food conducting tissue of the vascular plants. • It is a complex tissues formed of: • Sieve elements • Phloem fibers. • Parenchyma cells

  18. Vascular tissues

  19. Monocot Stem

  20. Monocot leaf Dicot leaf

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