Lecture 2 - Plant Tissues ( Part 2 ) | Plant Anatomy - Biotechnology Engineering (BT) PDF Download

 Page 1


 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
26 
 D) 
http://www.biologie.unihamburg.de/bonline/library/webb/BOT410/anatweb/images
/ParColSclr/MacroSclerEtc.jpg 
 E) http://www.biologie.uni-hamburg.de/b-
online/library/webb/BOT410/anatweb/images/ParColSclr/NymphLfXSLive2Scler.jpg
F) http://botweb.uwsp.edu/anatomy/images/schlerenchyma/pages/Anat0040.htm 
 
 Astrosclereids 
When the central body of cell develops arms or lobes like extension giving appearance of 
star are known as astrosclereids. They are found in leaf of eudicot, adaxial surface of leaf 
of N. cristata.  
Trichosclereids 
Tricosclereids are thin walled sclereids resembling hairs with branches. They are found on 
the adaxial surface of leaves of Olea europea and Banana leaf. 
Besides this two additional types of sclereids are also reported in plants: 
Filiform sclereids are long cylindrical cells similar to fibres and are found in palisade 
and spongy parenchyma of olive (Olea europaea) leaf.  
 
Figure: Filiform sclereid in leaf of Olea europaea. 
Source: http://images.botany.org/set-17/17-060h.jpg 
Fibre sclereids are the fibre that differentiates in phloem and have characteristic of both 
fibre and sclereids and thus named as fibre sclereids. They have been reported in 
secondary phloem of root and shoot of the rosette leaves of Arabidopsis thaliana. 
Sclereids are distributed in almost every organ of plant body ranging from epidermis, 
Page 2


 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
26 
 D) 
http://www.biologie.unihamburg.de/bonline/library/webb/BOT410/anatweb/images
/ParColSclr/MacroSclerEtc.jpg 
 E) http://www.biologie.uni-hamburg.de/b-
online/library/webb/BOT410/anatweb/images/ParColSclr/NymphLfXSLive2Scler.jpg
F) http://botweb.uwsp.edu/anatomy/images/schlerenchyma/pages/Anat0040.htm 
 
 Astrosclereids 
When the central body of cell develops arms or lobes like extension giving appearance of 
star are known as astrosclereids. They are found in leaf of eudicot, adaxial surface of leaf 
of N. cristata.  
Trichosclereids 
Tricosclereids are thin walled sclereids resembling hairs with branches. They are found on 
the adaxial surface of leaves of Olea europea and Banana leaf. 
Besides this two additional types of sclereids are also reported in plants: 
Filiform sclereids are long cylindrical cells similar to fibres and are found in palisade 
and spongy parenchyma of olive (Olea europaea) leaf.  
 
Figure: Filiform sclereid in leaf of Olea europaea. 
Source: http://images.botany.org/set-17/17-060h.jpg 
Fibre sclereids are the fibre that differentiates in phloem and have characteristic of both 
fibre and sclereids and thus named as fibre sclereids. They have been reported in 
secondary phloem of root and shoot of the rosette leaves of Arabidopsis thaliana. 
Sclereids are distributed in almost every organ of plant body ranging from epidermis, 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
27 
ground tissue to vascular tissue and occur singly or in cluster. When they occur as singly 
they are known as idioblast. 
Dicot leaves are rich in variety of sclereids but are absent in monocots. Two pattern of 
distribution of sclereids are mainly observed in dicots; terminal pattern and diffuse 
pattern. In terminal pattern they are confined to ends of small veins as seen in Hakea, 
Mouriria, Boronia and Arthrocnemum whereas, in diffuse pattern either they occur either 
solitary or in groups dispersed throughout the tissue without any spatial relationship to 
the vein endings. The examples of diffuse pattern are seen in Olea, Osmanthus, 
Pseudotsuga and Trochodendron. 
Foliar structure as found in clove scale of garlic (Allium sativum) the sclereids forms part 
of the entire epidermis. The plant species having well developed intercellular spaces or 
air chambers possess trichosclereids such as Monstera deliciosa, Nymphaea (water lily) 
and Nymphaea (Yellow pond lily).  
Seeds contain seed coat which is hard and this hardness is due to development of 
secondary wall in the epidermis and in the layers or layers beneath the epidermis e.g. 
seeds of bean (Phaseolus), pea (Pisum), soybean (Glycine max) contain columnar 
macrosclereids in epidermis and osteosclereides beneath the epidermis. The seed coat of 
coconut (Cocos nucifera) contains ramiform pitted sclereids. 
 
 
 
 
 
 
Figure: Stone cells or sclereids 
Source: http://student.nu.ac.th/cherrycoke/lesson6.htm 
 
 
Page 3


 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
26 
 D) 
http://www.biologie.unihamburg.de/bonline/library/webb/BOT410/anatweb/images
/ParColSclr/MacroSclerEtc.jpg 
 E) http://www.biologie.uni-hamburg.de/b-
online/library/webb/BOT410/anatweb/images/ParColSclr/NymphLfXSLive2Scler.jpg
F) http://botweb.uwsp.edu/anatomy/images/schlerenchyma/pages/Anat0040.htm 
 
 Astrosclereids 
When the central body of cell develops arms or lobes like extension giving appearance of 
star are known as astrosclereids. They are found in leaf of eudicot, adaxial surface of leaf 
of N. cristata.  
Trichosclereids 
Tricosclereids are thin walled sclereids resembling hairs with branches. They are found on 
the adaxial surface of leaves of Olea europea and Banana leaf. 
Besides this two additional types of sclereids are also reported in plants: 
Filiform sclereids are long cylindrical cells similar to fibres and are found in palisade 
and spongy parenchyma of olive (Olea europaea) leaf.  
 
Figure: Filiform sclereid in leaf of Olea europaea. 
Source: http://images.botany.org/set-17/17-060h.jpg 
Fibre sclereids are the fibre that differentiates in phloem and have characteristic of both 
fibre and sclereids and thus named as fibre sclereids. They have been reported in 
secondary phloem of root and shoot of the rosette leaves of Arabidopsis thaliana. 
Sclereids are distributed in almost every organ of plant body ranging from epidermis, 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
27 
ground tissue to vascular tissue and occur singly or in cluster. When they occur as singly 
they are known as idioblast. 
Dicot leaves are rich in variety of sclereids but are absent in monocots. Two pattern of 
distribution of sclereids are mainly observed in dicots; terminal pattern and diffuse 
pattern. In terminal pattern they are confined to ends of small veins as seen in Hakea, 
Mouriria, Boronia and Arthrocnemum whereas, in diffuse pattern either they occur either 
solitary or in groups dispersed throughout the tissue without any spatial relationship to 
the vein endings. The examples of diffuse pattern are seen in Olea, Osmanthus, 
Pseudotsuga and Trochodendron. 
Foliar structure as found in clove scale of garlic (Allium sativum) the sclereids forms part 
of the entire epidermis. The plant species having well developed intercellular spaces or 
air chambers possess trichosclereids such as Monstera deliciosa, Nymphaea (water lily) 
and Nymphaea (Yellow pond lily).  
Seeds contain seed coat which is hard and this hardness is due to development of 
secondary wall in the epidermis and in the layers or layers beneath the epidermis e.g. 
seeds of bean (Phaseolus), pea (Pisum), soybean (Glycine max) contain columnar 
macrosclereids in epidermis and osteosclereides beneath the epidermis. The seed coat of 
coconut (Cocos nucifera) contains ramiform pitted sclereids. 
 
 
 
 
 
 
Figure: Stone cells or sclereids 
Source: http://student.nu.ac.th/cherrycoke/lesson6.htm 
 
 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
28 
Functions 
Sclereids provide mechanical strengths and plays important role in guiding light within 
mesophyll. They are responsible for gritty texture found in some fruits like pear. 
 
Complex tissue/ Vascular Tissue:  
A tissue that consists of several kinds of cells which functions together is called complex 
tissue. Xylem, phloem and vascular cambium (absent in monocot and lower plants) are 
example of complex tissue as they are involved in the water-conduction, transport of 
solutes and food material and are known as vascular tissue. The vascular plants also 
referred to as tracheophytes, which include seedless vascular plants of Lycopodiophyta 
(horsetails), Pteridophyta (ferns), gymnosperms and angiosperms. The terms 
tracheophyte (vascular plants) is given because of to the characteristic conducting 
element present in the xylem tissues known as the tracheary elements.  
 
Figure: Components in open and closed type of vascular bundles. 
Source: http://bioict.exteen.com/ 
Page 4


 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
26 
 D) 
http://www.biologie.unihamburg.de/bonline/library/webb/BOT410/anatweb/images
/ParColSclr/MacroSclerEtc.jpg 
 E) http://www.biologie.uni-hamburg.de/b-
online/library/webb/BOT410/anatweb/images/ParColSclr/NymphLfXSLive2Scler.jpg
F) http://botweb.uwsp.edu/anatomy/images/schlerenchyma/pages/Anat0040.htm 
 
 Astrosclereids 
When the central body of cell develops arms or lobes like extension giving appearance of 
star are known as astrosclereids. They are found in leaf of eudicot, adaxial surface of leaf 
of N. cristata.  
Trichosclereids 
Tricosclereids are thin walled sclereids resembling hairs with branches. They are found on 
the adaxial surface of leaves of Olea europea and Banana leaf. 
Besides this two additional types of sclereids are also reported in plants: 
Filiform sclereids are long cylindrical cells similar to fibres and are found in palisade 
and spongy parenchyma of olive (Olea europaea) leaf.  
 
Figure: Filiform sclereid in leaf of Olea europaea. 
Source: http://images.botany.org/set-17/17-060h.jpg 
Fibre sclereids are the fibre that differentiates in phloem and have characteristic of both 
fibre and sclereids and thus named as fibre sclereids. They have been reported in 
secondary phloem of root and shoot of the rosette leaves of Arabidopsis thaliana. 
Sclereids are distributed in almost every organ of plant body ranging from epidermis, 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
27 
ground tissue to vascular tissue and occur singly or in cluster. When they occur as singly 
they are known as idioblast. 
Dicot leaves are rich in variety of sclereids but are absent in monocots. Two pattern of 
distribution of sclereids are mainly observed in dicots; terminal pattern and diffuse 
pattern. In terminal pattern they are confined to ends of small veins as seen in Hakea, 
Mouriria, Boronia and Arthrocnemum whereas, in diffuse pattern either they occur either 
solitary or in groups dispersed throughout the tissue without any spatial relationship to 
the vein endings. The examples of diffuse pattern are seen in Olea, Osmanthus, 
Pseudotsuga and Trochodendron. 
Foliar structure as found in clove scale of garlic (Allium sativum) the sclereids forms part 
of the entire epidermis. The plant species having well developed intercellular spaces or 
air chambers possess trichosclereids such as Monstera deliciosa, Nymphaea (water lily) 
and Nymphaea (Yellow pond lily).  
Seeds contain seed coat which is hard and this hardness is due to development of 
secondary wall in the epidermis and in the layers or layers beneath the epidermis e.g. 
seeds of bean (Phaseolus), pea (Pisum), soybean (Glycine max) contain columnar 
macrosclereids in epidermis and osteosclereides beneath the epidermis. The seed coat of 
coconut (Cocos nucifera) contains ramiform pitted sclereids. 
 
 
 
 
 
 
Figure: Stone cells or sclereids 
Source: http://student.nu.ac.th/cherrycoke/lesson6.htm 
 
 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
28 
Functions 
Sclereids provide mechanical strengths and plays important role in guiding light within 
mesophyll. They are responsible for gritty texture found in some fruits like pear. 
 
Complex tissue/ Vascular Tissue:  
A tissue that consists of several kinds of cells which functions together is called complex 
tissue. Xylem, phloem and vascular cambium (absent in monocot and lower plants) are 
example of complex tissue as they are involved in the water-conduction, transport of 
solutes and food material and are known as vascular tissue. The vascular plants also 
referred to as tracheophytes, which include seedless vascular plants of Lycopodiophyta 
(horsetails), Pteridophyta (ferns), gymnosperms and angiosperms. The terms 
tracheophyte (vascular plants) is given because of to the characteristic conducting 
element present in the xylem tissues known as the tracheary elements.  
 
Figure: Components in open and closed type of vascular bundles. 
Source: http://bioict.exteen.com/ 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
29 
 
Figure: A) Detailed structure of closed type vascular bundle B) Vascular bundle from 
Ranunculus stem (open type) 
Source:A)http://botit.botany.wisc.edu/Resources/Botany/Shoot/Stem/Zea%20stem/Vasc
ular%20Bundle%20MC%20.jpg.html 
B)http://www.uri.edu/cels/bio/plant_anatomy/106.html 
Xylem 
Xylem (Greek word ‘xylos’= wood) is an example of complex tissue forming a part of 
vascular tissue. The term xylem was introduced by Nägeli in 1858. Xylem is mainly 
responsible for the conduction of water and mineral salts from roots to rest of the plant. 
Two type of xylem tissue have been demarcated in plants - primary xylem and secondary 
xylem. If the origin of xylem tissue has occurred from procambium of apical meristem, it 
is called as primary xylem and if it has occurred from vascular cambium the xylem is 
called as secondary xylem. The primary xylem develops early in the life of plant than 
secondary xylem. Presence and absence of cambium in vascular bundle develops open 
and closed type of Vascular bundles respectively. Xylem tissue consists of four kinds of 
cells –  
a) Tracheids 
b) Vessels or tracheae 
c) Xylem fibres  
d) Xylem parenchyma 
Page 5


 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
26 
 D) 
http://www.biologie.unihamburg.de/bonline/library/webb/BOT410/anatweb/images
/ParColSclr/MacroSclerEtc.jpg 
 E) http://www.biologie.uni-hamburg.de/b-
online/library/webb/BOT410/anatweb/images/ParColSclr/NymphLfXSLive2Scler.jpg
F) http://botweb.uwsp.edu/anatomy/images/schlerenchyma/pages/Anat0040.htm 
 
 Astrosclereids 
When the central body of cell develops arms or lobes like extension giving appearance of 
star are known as astrosclereids. They are found in leaf of eudicot, adaxial surface of leaf 
of N. cristata.  
Trichosclereids 
Tricosclereids are thin walled sclereids resembling hairs with branches. They are found on 
the adaxial surface of leaves of Olea europea and Banana leaf. 
Besides this two additional types of sclereids are also reported in plants: 
Filiform sclereids are long cylindrical cells similar to fibres and are found in palisade 
and spongy parenchyma of olive (Olea europaea) leaf.  
 
Figure: Filiform sclereid in leaf of Olea europaea. 
Source: http://images.botany.org/set-17/17-060h.jpg 
Fibre sclereids are the fibre that differentiates in phloem and have characteristic of both 
fibre and sclereids and thus named as fibre sclereids. They have been reported in 
secondary phloem of root and shoot of the rosette leaves of Arabidopsis thaliana. 
Sclereids are distributed in almost every organ of plant body ranging from epidermis, 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
27 
ground tissue to vascular tissue and occur singly or in cluster. When they occur as singly 
they are known as idioblast. 
Dicot leaves are rich in variety of sclereids but are absent in monocots. Two pattern of 
distribution of sclereids are mainly observed in dicots; terminal pattern and diffuse 
pattern. In terminal pattern they are confined to ends of small veins as seen in Hakea, 
Mouriria, Boronia and Arthrocnemum whereas, in diffuse pattern either they occur either 
solitary or in groups dispersed throughout the tissue without any spatial relationship to 
the vein endings. The examples of diffuse pattern are seen in Olea, Osmanthus, 
Pseudotsuga and Trochodendron. 
Foliar structure as found in clove scale of garlic (Allium sativum) the sclereids forms part 
of the entire epidermis. The plant species having well developed intercellular spaces or 
air chambers possess trichosclereids such as Monstera deliciosa, Nymphaea (water lily) 
and Nymphaea (Yellow pond lily).  
Seeds contain seed coat which is hard and this hardness is due to development of 
secondary wall in the epidermis and in the layers or layers beneath the epidermis e.g. 
seeds of bean (Phaseolus), pea (Pisum), soybean (Glycine max) contain columnar 
macrosclereids in epidermis and osteosclereides beneath the epidermis. The seed coat of 
coconut (Cocos nucifera) contains ramiform pitted sclereids. 
 
 
 
 
 
 
Figure: Stone cells or sclereids 
Source: http://student.nu.ac.th/cherrycoke/lesson6.htm 
 
 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
28 
Functions 
Sclereids provide mechanical strengths and plays important role in guiding light within 
mesophyll. They are responsible for gritty texture found in some fruits like pear. 
 
Complex tissue/ Vascular Tissue:  
A tissue that consists of several kinds of cells which functions together is called complex 
tissue. Xylem, phloem and vascular cambium (absent in monocot and lower plants) are 
example of complex tissue as they are involved in the water-conduction, transport of 
solutes and food material and are known as vascular tissue. The vascular plants also 
referred to as tracheophytes, which include seedless vascular plants of Lycopodiophyta 
(horsetails), Pteridophyta (ferns), gymnosperms and angiosperms. The terms 
tracheophyte (vascular plants) is given because of to the characteristic conducting 
element present in the xylem tissues known as the tracheary elements.  
 
Figure: Components in open and closed type of vascular bundles. 
Source: http://bioict.exteen.com/ 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
29 
 
Figure: A) Detailed structure of closed type vascular bundle B) Vascular bundle from 
Ranunculus stem (open type) 
Source:A)http://botit.botany.wisc.edu/Resources/Botany/Shoot/Stem/Zea%20stem/Vasc
ular%20Bundle%20MC%20.jpg.html 
B)http://www.uri.edu/cels/bio/plant_anatomy/106.html 
Xylem 
Xylem (Greek word ‘xylos’= wood) is an example of complex tissue forming a part of 
vascular tissue. The term xylem was introduced by Nägeli in 1858. Xylem is mainly 
responsible for the conduction of water and mineral salts from roots to rest of the plant. 
Two type of xylem tissue have been demarcated in plants - primary xylem and secondary 
xylem. If the origin of xylem tissue has occurred from procambium of apical meristem, it 
is called as primary xylem and if it has occurred from vascular cambium the xylem is 
called as secondary xylem. The primary xylem develops early in the life of plant than 
secondary xylem. Presence and absence of cambium in vascular bundle develops open 
and closed type of Vascular bundles respectively. Xylem tissue consists of four kinds of 
cells –  
a) Tracheids 
b) Vessels or tracheae 
c) Xylem fibres  
d) Xylem parenchyma 
 
Plant Tissues 
Institute of Life Long Learning, University of Delhi 
 
30 
The term tracheid is derived from “trachea” because of its resemblance with insect 
tracheae. There are two types of tracheary elements in xylem, tracheids and vessel 
elements. Both are nonliving at maturity and more or less elongated cells. They have 
lignified secondary walls.  
The primary xylem develops earlier and are first formed elements called as protoxylem 
(from the Greek proto, first) and a later formed part are called as metaxylem (from the 
Greek meta, after or beyond). The protoxylem differentiates in parts of primary plant 
body where growth and differentiation has not yet completed. The protoxylem usually 
contains few tracheary elements (tracheids or vessel). The metaxylem begins to 
differentiate in the growing primary plant body and gets mature after elongation is 
completed and it contains more tracheary elements. 
 
Figure: Ranunculus root vascular cylinder showing the metaxylem (central last maturing 
xylem) with fully formed lignified secondary cell walls.  
Source:http://www.lima.ohiostate.edu/biology/archive/roots.html 
The secondary xylem is formed by a complex meristem known as vascular cambium, 
consisting of vertically elongated fusiform initials and squarish or horizontally (radially) 
elongated ray initials and such development distinguishes it from the architecture of 
primary xylem. The composition of secondary xylem found is more complex than the 
primary xylem in having a wider variety of cells in the angiosperms. 
Tracheids 
Tracheids are elongated cell with blunt ends, present along the long axis of the plant 
system. Phylogenetically the tracheids are most primitive type of cell found in xylem.