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
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