Downloaded 19 times
More Related Content
Similar to Complex permanent tissue
Complex permanent tissue
- 1. Complex permanent tissues Dr.K. GANESH KUMARI ASSISTANT PROFESSOR SRIMAD ANDAVAN ARTS AND SCIENCE COLLEGE (AUTONOMOUS) TRICHY, TAMILNADU, INDIA
- 2. Xylem • A conductiontissue in plants • Complex tissue formed of many types of cells • Term proposed by Nageli (1958) • Greek : xylos – wood • Main function – conduction of water and minerals from roots to leaves • Additional function – provides mechanical support
- 3. • It consistsof both living and non living cells Two types of xylem in plants – 1. Primary xylem – formed from the pro meristem (procambium) during primary growth 2. Secondary xylem - formed from the vascular cambium during secondary growth
- 4. Components or elementsof xylem • The elements of xylem are i. Tracheids ii. Vessels iii. Xylem fibres iv. Xylem parenchyma
- 5. i. Tracheids • Origin– Procambium • Structure – Elongated or tube like cell Consists of hard, moderately thick and lignified cell walls with large cavity Devoid of protoplast in maturity Ends are tapering, blunt and chisel – like Primitive type of cells Found in the fossils of seed plants
- 6. Cells with secondarycell walls Cells appear circular, polygonal or polyhedral in cross sections Average length 5 – 6 mm Major parts of the cells imperforate Only have pit – pairs at common walls
- 7. Patterns of secondarythickenings • Secondary cell wall materials are laid down on the lateral walls of tracheids –Annular thickening –Spiral (or) helical thickening –Scalariform thickening –Reticulate thickening –Pitted thickening
- 8. Annular thickening • Secondarythickening occurs as ring • Lignin deposition occurs as ring one above the other • Most primitive type thickening • Provides mechanical strength to the wall
- 9. Spiral (or) helical thickening •Also called spiral thickening • Secondary walls deposited as spirals • It is stronger than annular thickening
- 10. Scalariform thickening • Alsocalled like ladder like thickenings • Wall materials deposited as transverse bands • Bands are with few interconnections • Pits occurs in between thickenings
- 11. Reticulate thickening • Alsocalled as net like thickening • Net like distribution of secondary materials
- 12. Pitted thickening • Entireinner surface is thickened • Unthicken areas looks like pits • Used for the communication with neighbouring cells Two types of pits • Simple pits – Areas with primary walls • Bordered pits – Areas with secondary walls
- 13. • Its secondarywall outgrowths – dome like structure with perforation
- 14. • The primarywall thickening is called torus • In gymnosperms, torus is surrounded by microfibrils, known as margo
- 15. Functions of Tracheids •For the transport of water and minerals • Chief supporting element in gymnosperms • Provides mechanical support
- 17. ii. Vessels - Itis multicellular elongated tubes - It is formed from a row of cylindrical cells end to end with end walls - The end walls are perforated – perforation plate - The perforation plate is of two types a. Simple perforation b. Multiple perforation
- 18. a. Simple PerforationPlate • The Perforation plate contains one large pore
- 19. b. Multiple perforation •The perforation plate contains many pores
- 20. i. Reticulate type •The pores are arranged in reticulate manner
- 21. i. Scalariform type •The pores are elongated and arranged in parallel series
- 22. ii. Foraminate type •The perforations are circular and grouped together
- 23. iv. Xylem parenchyma •The parenchyma cells associated with the xylem is called Xylem Parenchyma • This is the living element of xylem • It is of two types – Ray parenchyma – derived from ray initials – Axial parenchyma – derived from elongated fusiform cambial cells • Xylem Parenchyma stores food • It also helps in conduction of water
- 25.