Page 1
Root Apex
Institute of Lifelong Learning, University of Delhi
Lesson Prepared under MHRD project “Natio n al Mission on
Education through IC T”
Discipline: Botany
Paper: Plant Anatomy
National Coordinator: Prof. S.C. Bhatla
Lesson: Root Apex
Lesson Developer: Mrs Meenam Bhatia
Daulat Ram College, University of Delhi
Lesson Reviewer: Dr Vibha Kaushik
Department/College: Department of Botany, University of Delhi
Language Editor: Namrata Dhaka
Department/College: Department of Genetics, University of Delhi,
South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Page 2
Root Apex
Institute of Lifelong Learning, University of Delhi
Lesson Prepared under MHRD project “Natio n al Mission on
Education through IC T”
Discipline: Botany
Paper: Plant Anatomy
National Coordinator: Prof. S.C. Bhatla
Lesson: Root Apex
Lesson Developer: Mrs Meenam Bhatia
Daulat Ram College, University of Delhi
Lesson Reviewer: Dr Vibha Kaushik
Department/College: Department of Botany, University of Delhi
Language Editor: Namrata Dhaka
Department/College: Department of Genetics, University of Delhi,
South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Root Apex
Institute of Lifelong Learning, University of Delhi 1
Chapter: Root Apex
Table of Contents
? Introduction
? Anatomy of root apex
? Cellular organization of root apex
? Root cap
? Apical Meristem
? Zone of Elongation
? Zone of Maturation
? Internal organization of apical meristem
? Apical cell theory
? Histogen theory
? Open root meristem
? Closed root meristem
? Korper-kappe theory
? Quiescent center
? Summary
? Exercise/ Practice
? Glossary
? References
? Web links
Page 3
Root Apex
Institute of Lifelong Learning, University of Delhi
Lesson Prepared under MHRD project “Natio n al Mission on
Education through IC T”
Discipline: Botany
Paper: Plant Anatomy
National Coordinator: Prof. S.C. Bhatla
Lesson: Root Apex
Lesson Developer: Mrs Meenam Bhatia
Daulat Ram College, University of Delhi
Lesson Reviewer: Dr Vibha Kaushik
Department/College: Department of Botany, University of Delhi
Language Editor: Namrata Dhaka
Department/College: Department of Genetics, University of Delhi,
South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Root Apex
Institute of Lifelong Learning, University of Delhi 1
Chapter: Root Apex
Table of Contents
? Introduction
? Anatomy of root apex
? Cellular organization of root apex
? Root cap
? Apical Meristem
? Zone of Elongation
? Zone of Maturation
? Internal organization of apical meristem
? Apical cell theory
? Histogen theory
? Open root meristem
? Closed root meristem
? Korper-kappe theory
? Quiescent center
? Summary
? Exercise/ Practice
? Glossary
? References
? Web links
Root Apex
Institute of Lifelong Learning, University of Delhi 2
Introduction
The meristems located at the apices of plant organs are called apical meristems. Root apex
is a term used to refer to the root apical meristem.
Figure: The contribution of shoot apical meristem and root apical meristem to the growth of
Arabidopsis plant. Both meristems are about 100µm in diameter and contain about 100
cells.
Source: http://www.nature.com/nature/journal/v415/n6873/pdf/415751a.pdf
Root apex is much simpler in its structure than shoot apex. The apical meristem of root can
be distinguished from shoot apex in lacking the developing appendages like leaf primordia,
leaf trace or axillary bud. Hence it is continuous and shows no periodic changes in shape
and structure during its development as shown by shoot apices on leaf initiation. Unlike
shoot apical meristem, it is bipolar in nature as it adds new cells both distally and
proximally. The distal cells derivatives give rise to a root cap and the proximal cells elongate
and differentiate into mature tissue of the root. Thus the growth of root apex is antagonistic
Page 4
Root Apex
Institute of Lifelong Learning, University of Delhi
Lesson Prepared under MHRD project “Natio n al Mission on
Education through IC T”
Discipline: Botany
Paper: Plant Anatomy
National Coordinator: Prof. S.C. Bhatla
Lesson: Root Apex
Lesson Developer: Mrs Meenam Bhatia
Daulat Ram College, University of Delhi
Lesson Reviewer: Dr Vibha Kaushik
Department/College: Department of Botany, University of Delhi
Language Editor: Namrata Dhaka
Department/College: Department of Genetics, University of Delhi,
South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Root Apex
Institute of Lifelong Learning, University of Delhi 1
Chapter: Root Apex
Table of Contents
? Introduction
? Anatomy of root apex
? Cellular organization of root apex
? Root cap
? Apical Meristem
? Zone of Elongation
? Zone of Maturation
? Internal organization of apical meristem
? Apical cell theory
? Histogen theory
? Open root meristem
? Closed root meristem
? Korper-kappe theory
? Quiescent center
? Summary
? Exercise/ Practice
? Glossary
? References
? Web links
Root Apex
Institute of Lifelong Learning, University of Delhi 2
Introduction
The meristems located at the apices of plant organs are called apical meristems. Root apex
is a term used to refer to the root apical meristem.
Figure: The contribution of shoot apical meristem and root apical meristem to the growth of
Arabidopsis plant. Both meristems are about 100µm in diameter and contain about 100
cells.
Source: http://www.nature.com/nature/journal/v415/n6873/pdf/415751a.pdf
Root apex is much simpler in its structure than shoot apex. The apical meristem of root can
be distinguished from shoot apex in lacking the developing appendages like leaf primordia,
leaf trace or axillary bud. Hence it is continuous and shows no periodic changes in shape
and structure during its development as shown by shoot apices on leaf initiation. Unlike
shoot apical meristem, it is bipolar in nature as it adds new cells both distally and
proximally. The distal cells derivatives give rise to a root cap and the proximal cells elongate
and differentiate into mature tissue of the root. Thus the growth of root apex is antagonistic
Root Apex
Institute of Lifelong Learning, University of Delhi 3
i.e., it is occurs in both directions, towards the axis and away from axis. Also it is sub
terminal in position because of the presence of a protective tissue root cap at its tip.
Additionally, it provides a shield to the inner meristematic tissue against the mechanical
obstacles, root cap cells secrete a complex polysaccharide mucigel (mucilage). It enables
the root to penetrate the soil by lubricating the passage.
Figure: Diagrammatic sketch of L.S. Shoot tip (A) and root tip (B) of Linum usitatissimum
Source: Esau, K. 1960. Anatomy of Seed Plants, John Wiley & Sons, Inc., NY.
Page 5
Root Apex
Institute of Lifelong Learning, University of Delhi
Lesson Prepared under MHRD project “Natio n al Mission on
Education through IC T”
Discipline: Botany
Paper: Plant Anatomy
National Coordinator: Prof. S.C. Bhatla
Lesson: Root Apex
Lesson Developer: Mrs Meenam Bhatia
Daulat Ram College, University of Delhi
Lesson Reviewer: Dr Vibha Kaushik
Department/College: Department of Botany, University of Delhi
Language Editor: Namrata Dhaka
Department/College: Department of Genetics, University of Delhi,
South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Root Apex
Institute of Lifelong Learning, University of Delhi 1
Chapter: Root Apex
Table of Contents
? Introduction
? Anatomy of root apex
? Cellular organization of root apex
? Root cap
? Apical Meristem
? Zone of Elongation
? Zone of Maturation
? Internal organization of apical meristem
? Apical cell theory
? Histogen theory
? Open root meristem
? Closed root meristem
? Korper-kappe theory
? Quiescent center
? Summary
? Exercise/ Practice
? Glossary
? References
? Web links
Root Apex
Institute of Lifelong Learning, University of Delhi 2
Introduction
The meristems located at the apices of plant organs are called apical meristems. Root apex
is a term used to refer to the root apical meristem.
Figure: The contribution of shoot apical meristem and root apical meristem to the growth of
Arabidopsis plant. Both meristems are about 100µm in diameter and contain about 100
cells.
Source: http://www.nature.com/nature/journal/v415/n6873/pdf/415751a.pdf
Root apex is much simpler in its structure than shoot apex. The apical meristem of root can
be distinguished from shoot apex in lacking the developing appendages like leaf primordia,
leaf trace or axillary bud. Hence it is continuous and shows no periodic changes in shape
and structure during its development as shown by shoot apices on leaf initiation. Unlike
shoot apical meristem, it is bipolar in nature as it adds new cells both distally and
proximally. The distal cells derivatives give rise to a root cap and the proximal cells elongate
and differentiate into mature tissue of the root. Thus the growth of root apex is antagonistic
Root Apex
Institute of Lifelong Learning, University of Delhi 3
i.e., it is occurs in both directions, towards the axis and away from axis. Also it is sub
terminal in position because of the presence of a protective tissue root cap at its tip.
Additionally, it provides a shield to the inner meristematic tissue against the mechanical
obstacles, root cap cells secrete a complex polysaccharide mucigel (mucilage). It enables
the root to penetrate the soil by lubricating the passage.
Figure: Diagrammatic sketch of L.S. Shoot tip (A) and root tip (B) of Linum usitatissimum
Source: Esau, K. 1960. Anatomy of Seed Plants, John Wiley & Sons, Inc., NY.
Root Apex
Institute of Lifelong Learning, University of Delhi 4
A. B.
Figure: A.L.S. Coleus shoot apex; B. L.S. Root apex
Source:http://www.doctortee.com/cgi/image-lookup.cgi?coleus-stem-tip
;www.daviddarling.info/encyclopedia/P/plant_root.html
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