Page 1
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: Trichomes and Stomata
Lesson Developer: Dr Smriti Singh
Department/College: Acharya Narender Dev College
Lesson Reviewer: Dr Girish Mishra
Department/College: Botany, University of Delhi
Language Editor: Dr Sonal Bhatnagar
Department/College: Hindu College
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Page 2
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: Trichomes and Stomata
Lesson Developer: Dr Smriti Singh
Department/College: Acharya Narender Dev College
Lesson Reviewer: Dr Girish Mishra
Department/College: Botany, University of Delhi
Language Editor: Dr Sonal Bhatnagar
Department/College: Hindu College
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Trichomes and Stomata
Institute of Lifelong Learning, University of Delhi 1
Table of Contents
Chapter: Trichomes and Stomata
? Trichomes
? Types
? Glandular trichomes
? Non glandular trivhomes
? Functions
? Stomata
? Types
? Functions
? Summary
? Glossary
? Exercise
? References
Page 3
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: Trichomes and Stomata
Lesson Developer: Dr Smriti Singh
Department/College: Acharya Narender Dev College
Lesson Reviewer: Dr Girish Mishra
Department/College: Botany, University of Delhi
Language Editor: Dr Sonal Bhatnagar
Department/College: Hindu College
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Trichomes and Stomata
Institute of Lifelong Learning, University of Delhi 1
Table of Contents
Chapter: Trichomes and Stomata
? Trichomes
? Types
? Glandular trichomes
? Non glandular trivhomes
? Functions
? Stomata
? Types
? Functions
? Summary
? Glossary
? Exercise
? References
Trichomes and Stomata
Institute of Life Long Learning, University of Delhi
2
Trichomes
Trichomes are the unicellular or multicellular epidermal appendages that occur in various
morphological forms like hairs, scales, warts, papillae etc. They can be persistent or
ephemeral (fall off) e.g. Lantania verschaffeltii. They are found on almost all the above
ground parts (shoot) of the plant body. All the trichomes on a plant body are collectively
referred to as indumentums.
Different types of trichomes
Trichomes are of two types: glandular and non-glandular. Glandular trichomes secrete
water, salt, mucilage, nectar, alkaloid, terpenes, resins etc. They are also known as
secretory trichomes or glands. They can also be classified on the basis of number of cells
(unicellular/multicellular) and layers (uniseriate/multiseriate). Multicellular or multiseriate
trichomes are also known as shaggy e.g. Anabasis, Cleome.
Figure: Classification of trichomes
Glandular
Trichomes
(unicellular/multicellular)
epidermal appendages
Lipophilic
Ocimum,
Mentha
Non-glandular
Vesicular hair
(non-flattened)
Gossypium, Triticum
Squamiform
hair
(flattened)
Stellate
Styrax,
Platanus
T-shaped
Corokia,
Olearia
Scales
(sessile)
Croton,
Bromeliaceae
Peltate
(Stalked)
Oleo
Dendroid
Brassica,
Iberis
Hydrophilic
Atriplex,
Rumex
Page 4
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: Trichomes and Stomata
Lesson Developer: Dr Smriti Singh
Department/College: Acharya Narender Dev College
Lesson Reviewer: Dr Girish Mishra
Department/College: Botany, University of Delhi
Language Editor: Dr Sonal Bhatnagar
Department/College: Hindu College
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Trichomes and Stomata
Institute of Lifelong Learning, University of Delhi 1
Table of Contents
Chapter: Trichomes and Stomata
? Trichomes
? Types
? Glandular trichomes
? Non glandular trivhomes
? Functions
? Stomata
? Types
? Functions
? Summary
? Glossary
? Exercise
? References
Trichomes and Stomata
Institute of Life Long Learning, University of Delhi
2
Trichomes
Trichomes are the unicellular or multicellular epidermal appendages that occur in various
morphological forms like hairs, scales, warts, papillae etc. They can be persistent or
ephemeral (fall off) e.g. Lantania verschaffeltii. They are found on almost all the above
ground parts (shoot) of the plant body. All the trichomes on a plant body are collectively
referred to as indumentums.
Different types of trichomes
Trichomes are of two types: glandular and non-glandular. Glandular trichomes secrete
water, salt, mucilage, nectar, alkaloid, terpenes, resins etc. They are also known as
secretory trichomes or glands. They can also be classified on the basis of number of cells
(unicellular/multicellular) and layers (uniseriate/multiseriate). Multicellular or multiseriate
trichomes are also known as shaggy e.g. Anabasis, Cleome.
Figure: Classification of trichomes
Glandular
Trichomes
(unicellular/multicellular)
epidermal appendages
Lipophilic
Ocimum,
Mentha
Non-glandular
Vesicular hair
(non-flattened)
Gossypium, Triticum
Squamiform
hair
(flattened)
Stellate
Styrax,
Platanus
T-shaped
Corokia,
Olearia
Scales
(sessile)
Croton,
Bromeliaceae
Peltate
(Stalked)
Oleo
Dendroid
Brassica,
Iberis
Hydrophilic
Atriplex,
Rumex
Trichomes and Stomata
Institute of Life Long Learning, University of Delhi
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Figure: Different types of trichomes
Source: http://www.cas.miamioh.edu/~meicenrd/ANATOMY/Ch11_Secretory/trichomes.jpg
Glandular trichomes
These can be classified as hydrophilic and lipophilic, depending upon the nature of their
secretions. In the former type, the secretion is in the form of an aqueous solution, whereas,
the latter secrets resins, essential oils, waxes and lipids. Glandular trichomes consist of a
secretory apical bulbous cell attached to non-secretory stalk and basal cells. In some
species there are collecting cells which are modified epidermal cells. Similar to epidermal
cells, trichomes also have cuticle covering and secreted substances accumulate beneath the
Page 5
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: Trichomes and Stomata
Lesson Developer: Dr Smriti Singh
Department/College: Acharya Narender Dev College
Lesson Reviewer: Dr Girish Mishra
Department/College: Botany, University of Delhi
Language Editor: Dr Sonal Bhatnagar
Department/College: Hindu College
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Trichomes and Stomata
Institute of Lifelong Learning, University of Delhi 1
Table of Contents
Chapter: Trichomes and Stomata
? Trichomes
? Types
? Glandular trichomes
? Non glandular trivhomes
? Functions
? Stomata
? Types
? Functions
? Summary
? Glossary
? Exercise
? References
Trichomes and Stomata
Institute of Life Long Learning, University of Delhi
2
Trichomes
Trichomes are the unicellular or multicellular epidermal appendages that occur in various
morphological forms like hairs, scales, warts, papillae etc. They can be persistent or
ephemeral (fall off) e.g. Lantania verschaffeltii. They are found on almost all the above
ground parts (shoot) of the plant body. All the trichomes on a plant body are collectively
referred to as indumentums.
Different types of trichomes
Trichomes are of two types: glandular and non-glandular. Glandular trichomes secrete
water, salt, mucilage, nectar, alkaloid, terpenes, resins etc. They are also known as
secretory trichomes or glands. They can also be classified on the basis of number of cells
(unicellular/multicellular) and layers (uniseriate/multiseriate). Multicellular or multiseriate
trichomes are also known as shaggy e.g. Anabasis, Cleome.
Figure: Classification of trichomes
Glandular
Trichomes
(unicellular/multicellular)
epidermal appendages
Lipophilic
Ocimum,
Mentha
Non-glandular
Vesicular hair
(non-flattened)
Gossypium, Triticum
Squamiform
hair
(flattened)
Stellate
Styrax,
Platanus
T-shaped
Corokia,
Olearia
Scales
(sessile)
Croton,
Bromeliaceae
Peltate
(Stalked)
Oleo
Dendroid
Brassica,
Iberis
Hydrophilic
Atriplex,
Rumex
Trichomes and Stomata
Institute of Life Long Learning, University of Delhi
3
Figure: Different types of trichomes
Source: http://www.cas.miamioh.edu/~meicenrd/ANATOMY/Ch11_Secretory/trichomes.jpg
Glandular trichomes
These can be classified as hydrophilic and lipophilic, depending upon the nature of their
secretions. In the former type, the secretion is in the form of an aqueous solution, whereas,
the latter secrets resins, essential oils, waxes and lipids. Glandular trichomes consist of a
secretory apical bulbous cell attached to non-secretory stalk and basal cells. In some
species there are collecting cells which are modified epidermal cells. Similar to epidermal
cells, trichomes also have cuticle covering and secreted substances accumulate beneath the
Trichomes and Stomata
Institute of Life Long Learning, University of Delhi
4
cuticle, which are secreted out subsequently either by rupture of cuticle or through pores in
it.
Hydrophilic type
1) Salt secreting trichomes: These are very common in halophytes and marshy plants
such as Tamarix, Avicenna and Atriplex. They secrete out the excess salt and help in
maintaining the osmolarity. In Atriplex salt secreting structure consists of a stalk of two to
three cells and a vesiculate head which has large vacuoles where the salt solution
accumulates. Once they are full of salt, the trichome withers away and the stalk remains on
the leaf surface as a salty deposit.
Figure: Salt gland in Atriplex B- bladder, C- cuticle, Ch- chlorophyll, E- epidermal cells, M-
mitochondria, P- plasmodesmata, v- vacuole
Source:http://upload.wikimedia.org/wikipedia/de/thumb/0/00/Halophyt02_003.jpg/220px-
Halophyt02_003.jpg
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