Lecture 8 - Periderm | Plant Anatomy - Biotechnology Engineering (BT) PDF Download

 Page 1


 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
0 
                                                                                              
 
Lesson Prepared Under MHRD project “National Mission 
on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Anatomy 
 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Periderm 
Lesson Developer: Dr Anupama Shukla 
Department/College: Acharya Narender Dev College 
 
 
Lesson Reviewer: Dr Basudha Sharma 
Department/College: MM (PG) College 
Modinagar, Uttar Pradesh 
 
Language Editor: Dr Sonal Bhatnagar 
Department/College: Ramanujan College 
 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Page 2


 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
0 
                                                                                              
 
Lesson Prepared Under MHRD project “National Mission 
on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Anatomy 
 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Periderm 
Lesson Developer: Dr Anupama Shukla 
Department/College: Acharya Narender Dev College 
 
 
Lesson Reviewer: Dr Basudha Sharma 
Department/College: MM (PG) College 
Modinagar, Uttar Pradesh 
 
Language Editor: Dr Sonal Bhatnagar 
Department/College: Ramanujan College 
 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
1 
Table of Contents  
Chapter: Periderm 
? Introduction  
? Cell structure          
? Development                    
? Position of phellogen         
? Rhytidome                                  
? Morphology of bark 
? Lenticel                                    
? Protective tissue in monocotyledons    
? Summary          
? Glossary    
? Exercise 
? References 
 
 
 
 
 
 
 
 
 
Page 3


 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
0 
                                                                                              
 
Lesson Prepared Under MHRD project “National Mission 
on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Anatomy 
 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Periderm 
Lesson Developer: Dr Anupama Shukla 
Department/College: Acharya Narender Dev College 
 
 
Lesson Reviewer: Dr Basudha Sharma 
Department/College: MM (PG) College 
Modinagar, Uttar Pradesh 
 
Language Editor: Dr Sonal Bhatnagar 
Department/College: Ramanujan College 
 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
1 
Table of Contents  
Chapter: Periderm 
? Introduction  
? Cell structure          
? Development                    
? Position of phellogen         
? Rhytidome                                  
? Morphology of bark 
? Lenticel                                    
? Protective tissue in monocotyledons    
? Summary          
? Glossary    
? Exercise 
? References 
 
 
 
 
 
 
 
 
 
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
2 
Introduction 
In most plants that have secondary growth, a layer of periderm develops, which is also 
known as cork. It is protective in function and replaces the epidermis of roots and stems, 
which is shed.  
 
Figure: Bark of a pine tree 
Source:http://en.wikipedia.org/wiki/Bark#mediaviewer/File:Pine_bark_tecpan_guatemala.J
PG,http://www4.uwsp.edu/biology/courses/botlab/Lab06b.htm 
Bark 
Bark 
Page 4


 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
0 
                                                                                              
 
Lesson Prepared Under MHRD project “National Mission 
on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Anatomy 
 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Periderm 
Lesson Developer: Dr Anupama Shukla 
Department/College: Acharya Narender Dev College 
 
 
Lesson Reviewer: Dr Basudha Sharma 
Department/College: MM (PG) College 
Modinagar, Uttar Pradesh 
 
Language Editor: Dr Sonal Bhatnagar 
Department/College: Ramanujan College 
 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
1 
Table of Contents  
Chapter: Periderm 
? Introduction  
? Cell structure          
? Development                    
? Position of phellogen         
? Rhytidome                                  
? Morphology of bark 
? Lenticel                                    
? Protective tissue in monocotyledons    
? Summary          
? Glossary    
? Exercise 
? References 
 
 
 
 
 
 
 
 
 
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
2 
Introduction 
In most plants that have secondary growth, a layer of periderm develops, which is also 
known as cork. It is protective in function and replaces the epidermis of roots and stems, 
which is shed.  
 
Figure: Bark of a pine tree 
Source:http://en.wikipedia.org/wiki/Bark#mediaviewer/File:Pine_bark_tecpan_guatemala.J
PG,http://www4.uwsp.edu/biology/courses/botlab/Lab06b.htm 
Bark 
Bark 
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
3 
Periderm is a secondary tissue and consists of three layers, the phellogen, phellem and 
phelloderm. The phellogen/cork cambium consists of a layer of meristematic cells which 
produce the phellem/cork towards the outer side and the phelloderm towards the inner side. 
 
Figure: A) T.S. of a stem showing secondary growth. B) Diagrammatic sketch 
Source:http://botit.botany.wisc.edu/Resources/Botany/Secondary%20Growth/Stem/Second
ary%20Growth/1%20year/Phloem%20cortex%20periderm%20labelled.jpg.html, 
A 
B 
Page 5


 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
0 
                                                                                              
 
Lesson Prepared Under MHRD project “National Mission 
on Education Through ICT” 
 
Discipline: Botany 
Paper: Plant Anatomy 
 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Periderm 
Lesson Developer: Dr Anupama Shukla 
Department/College: Acharya Narender Dev College 
 
 
Lesson Reviewer: Dr Basudha Sharma 
Department/College: MM (PG) College 
Modinagar, Uttar Pradesh 
 
Language Editor: Dr Sonal Bhatnagar 
Department/College: Ramanujan College 
 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
1 
Table of Contents  
Chapter: Periderm 
? Introduction  
? Cell structure          
? Development                    
? Position of phellogen         
? Rhytidome                                  
? Morphology of bark 
? Lenticel                                    
? Protective tissue in monocotyledons    
? Summary          
? Glossary    
? Exercise 
? References 
 
 
 
 
 
 
 
 
 
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
2 
Introduction 
In most plants that have secondary growth, a layer of periderm develops, which is also 
known as cork. It is protective in function and replaces the epidermis of roots and stems, 
which is shed.  
 
Figure: Bark of a pine tree 
Source:http://en.wikipedia.org/wiki/Bark#mediaviewer/File:Pine_bark_tecpan_guatemala.J
PG,http://www4.uwsp.edu/biology/courses/botlab/Lab06b.htm 
Bark 
Bark 
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
3 
Periderm is a secondary tissue and consists of three layers, the phellogen, phellem and 
phelloderm. The phellogen/cork cambium consists of a layer of meristematic cells which 
produce the phellem/cork towards the outer side and the phelloderm towards the inner side. 
 
Figure: A) T.S. of a stem showing secondary growth. B) Diagrammatic sketch 
Source:http://botit.botany.wisc.edu/Resources/Botany/Secondary%20Growth/Stem/Second
ary%20Growth/1%20year/Phloem%20cortex%20periderm%20labelled.jpg.html, 
A 
B 
 
 
Periderm 
 
Institute of Life Long Learning, University of Delhi 
 
4 
http://www.apsnet.org/edcenter/illglossary/Article%20Images/Forms/DispForm.aspx?ID=6
20 
 
Variations in pattern of development of periderm 
In some trees, periderm never develops and the epidermis is retained throughout life. In 
such plants, the cell wall of the epidermis thickens and cells divide radially and elongate 
tangentially, e.g. Viscum. In some other trees, the formation of periderm starts much later 
than the formation of secondary vascular tissue for example Citrus, Eucalyptus and Acer. In 
some other plants like Quercus suber and Aristolochia sp. a thick layer of cork develops. 
Periderm also develops at the site of wounding and is called wound periderm. Formation of 
periderm may also be observed at the site of leaf or branch abscission. 
Primary Growth vs Secondary growth 
Primary Growth: The development of a plant after germination of seed is called primary 
growth. It results in increase in shoot or root length, due to the division of cells at the apical 
meristems. The tissues that develop as a result of this growth are primary tissues, primary 
xylem and primary phloem. 
 
Figure: Primary and secondary growth 
 
Source:http://ap-bio-chs plants.wikispaces.com/Primary+Growth+vs.+Secondary+Growth