Anatomy of the Leaf _ Tutorvista
4
4/10/12 Anatomy of the Leaf | Tutorvista.com 1/4 www.tutorvista.com/content/biology/biology-iii/plant-histology/leaf-anatomy.php# Over 6,911,000 live tutoring sessions served! Home How it works About Us Home ▶ Biology ▶ ▶ Plant Histology ▶ Anatomy of a typical Dorsi-Ventral Leaf Back to Top Sub Topics 1. Anatomy of a typical Dorsi-Ventral Leaf 2. Diagnostic Features of a dorsiventral leaf 3. Anatomy of a typical iso-bilateral leaf 4. Diagnostic Feature of an isobilateral leaf 5. Difference between dicot leaf and monocot leaf Anatomy of the Leaf 0 Leaf represents an important part of the plant body. It is involved in vital physiological activities such as transpiration, respiration and photosynthesis. Unlike the stem and the root, the leaf is flat and hence, the anatomy of the leaf differs very much from that of stem or root. There are two types of leaves in angiosperms based on the manner of orientation, they are: Dorsi-ventral leaves which usually orient at an angle to the main axis and held perpendicular (normal) to the direction of sunlight. Example: Leaves of dicots Iso-bilateral leaves which usually orient parallely to the main axis and held parallel to the direction of the sunlight . Example: Leaves of monocots. A characateristic feature of leaves is the presence of two epidermal layers, one on each surface. The ground tissue that occurs between the two epidermal layers, is known as mesophyll. Embedded in the mesophyll are the vascular bundles, commonly known as veins. Example: Sunflower A transverse section through the midrib region of a typical dorsi-ventral leaf (Sunflower) reveals the following structure. Epidermis is in two layers, one on each surface of the leaf. Both the layers are composed of compactly arranged, barrel-shaped cells. Intercellular spaces are absent. A cuticle surrounds both the layers. Multicellular hairs called trichomes are Plant Histology Anatomy of the Leaf
Transcript of Anatomy of the Leaf _ Tutorvista
4/10/12 Anatomy of the Leaf | Tutorvista.com
1/4www.tutorvista.com/content/biology/biology-iii/plant-histology/leaf-anatomy.php#
Over 6,911,000 live tutoring sessions served!
Home How it works About Us
Home ▶ Biology ▶ ▶ Plant Histology ▶
Anatomy of a typical Dorsi-Ventral Leaf Back to Top
Sub Topics
1. Anatomy of a typical Dorsi-Ventral Leaf
2. Diagnostic Features of a dorsiventral leaf
3. Anatomy of a typical iso-bilateral leaf
4. Diagnostic Feature of an isobilateral leaf
5. Difference between dicot leaf and monocot leaf
Anatomy of the Leaf 0
Leaf represents an important part of the plant body. It is involved in vital physiological
activities such as transpiration, respiration and photosynthesis. Unlike the stem and the
root, the leaf is flat and hence, the anatomy of the leaf differs very much from that of stem
or root.
There are two types of leaves in angiosperms based on the manner of orientation, they
are:
Dorsi-ventral leaves which usually orient at an angle to the main axis and held
perpendicular (normal) to the direction of sunlight.
Example: Leaves of dicots
Iso-bilateral leaves which usually orient parallely to the main axis and held parallel
to the direction of the sunlight .
Example: Leaves of monocots.
A characateristic feature of leaves is the presence of two epidermal layers, one on each
surface. The ground tissue that occurs between the two epidermal layers, is known as
mesophyll. Embedded in the mesophyll are the vascular bundles, commonly known as
veins.
Example: Sunflower
A transverse section through the midrib region of a typical dorsi-ventral leaf (Sunflower)
reveals the following structure.
Epidermis is in two layers, one on each surface of the leaf. Both the layers are
composed of compactly arranged, barrel-shaped cells. Intercellular spaces are
absent. A cuticle surrounds both the layers. Multicellular hairs called trichomes are
Plant Histology
Anatomy of the Leaf
4/10/12 Anatomy of the Leaf | Tutorvista.com
2/4www.tutorvista.com/content/biology/biology-iii/plant-histology/leaf-anatomy.php#
Diagnostic Features of a dorsiventral leaf Back to Top
Anatomy of a typical iso-bilateral leaf Back to Top
present on both the layers. Stomata occur only in the lower epidermis. This
condition is described as hypostomatic.
Mesophyll is the ground tissue that occurs between the two epidermal layers. It is
exclusively composed of chlorenchyma cells. The mesophyll is characteristically
differentiated into two regions namely, an upper palisade parenchyma and a lower
spongy parenchyma.
a) Palisade parenchyma is composed of two or three layers of elongated, compactly
arranged chlorenchyma cells. Intercellular spaces are absent. The cells contain a very
large number of chloroplasts.
b) Spongy parenchyma is composed of a few layers of loosely arranged spherical or oval
chlorenchyma cells with prominent intercellular spaces. These cells contain very few
chloroplasts.
Veins represent the vascular bundles. They are found irregularly scattered in the
mesophyll due to reticulate venation. The largest and the oldest vein is found in the
centre. It is known as midrib vein.
T.S. through the midrib region of a dorsi-ventral leaf
Each vein has a bundle sheath composed of single layer of compactly arranged barrel
shaped parenchyma cells. The bundle sheath encloses both xylem and phloem. Xylem is
found towards upper epidermis and phloem towards lower epidermis. In the xylem many
protoxylem and metaxylem vessels are found. Protoxylem orients towards upper
epidermis. Hence, the vascular bundle are described as conjoint and collateral with
endarch xylem. The bundle sheath of the midrib vein is connected to the upper and the
lower epidermal layers by many layers of collenchyma cells, representing bundle sheath
extensions or hypodermal collenchyma.
Presence of two epidermal layers.
Presence of cuticle and trichomes in both the epidermal layers.
Hypostomatic condition.
Mesophyll differentiated into upper palisade parenchyma and lower spongy
parenchyma.
Veins irregularly scattered in the mesophyll.
Presence of a bundle sheath made up of parenchyma.
Vascular bundles are conjoint, collateral with endarch xylem.
Presence of bundle sheath extensions made up of collenchyma.
Example: Maize
A transverse section passing through the midrib region of an iso-bilateral leaf (Maize)
reveals the following structure.
Epidermis is in two layers, one on each surface of the leaf. Both the epidermal
layers are composed of compactly arranged, barrel shaped cells. Cuticle and
4/10/12 Anatomy of the Leaf | Tutorvista.com
3/4www.tutorvista.com/content/biology/biology-iii/plant-histology/leaf-anatomy.php#
Diagnostic Feature of an isobilateral leaf Back to Top
Difference between dicot leaf and monocot leaf Back to Top
trichomes are present in both the layers. Stomata are found in both the epidermal
layers. This condition is described as amphistomatic. A few cells in the upper
epidermis are enlarged to form motor cells called bulliform cells.
Mesophyll is ground tissue that occurs between the two epidermal layers. It is
composed of many layers of loosely arranged, spherical or oval chlorenchyma
cells. Intercellular spaces are prominent.
T.S. through an isobilateral leaf
Veins are found parallely arranged in the mesophyll (parallel venation). Each
vascular bundle is surrounded by a bundle sheath composed of a single layer of
compactly arranged barrel-shaped cells. The bundle sheath encloses both phloem
and xylem. Phloem is found towards lower epidermis and xylem towards upper
epidermis. In the xylem, only two protoxylem and two metaxylem vessels are
present. The vascular bundle is described as conjoint and collateral with endarch
xylem.
The oldest and the largest vascular bundle is found in the centre. It is known as midrib
vein. The bundle sheath of the midrib vein is connected to the upper and lower epidermal
layers by sclerenchyma cells representing bundle sheath extensions or hypodermal
sclerenchyma.
Presence of two epidermal layers.
Presence of cuticle and trichomes in both the layers.
Amphistomatic condition.
Presence of motor cells in the upper epidermis.
Presence of undifferentiated mesophyll.
Vascular bundles parallely arranged.
Presence of a bundle sheath around each bundle.
Vascular bundles conjoint, collateral with endarch xylem.
Presence of only two protoxylem and two metaxylem vessels in each bundle.
Presence of hypodermal sclerenchyma.
4/10/12 Anatomy of the Leaf | Tutorvista.com
4/4www.tutorvista.com/content/biology/biology-iii/plant-histology/leaf-anatomy.php#
0
*AP and SAT are registered trademarks of the College Board.
About Us | Contact Us | Blog | Homew ork Help | Teaching Jobs | Search Lessons | Answ ers | Calculators | Worksheets
Copyright © 2010 - TutorVista.com, All rights reserved.
Online Shopping Landmarkonthenet.com/online+shopping
10148256 items to shop online, get upto 80% off +Free Shipping + COD
Save up to 90% - Surat www.transactdeals.com
Visit us for most exiting deals Enjoy Life More ForLess Money
12th Board + MBBS Exams www.topMBBScoaching.com
Class 12th P, C & B with Entrance Exams Focus ForAIPMT, AIIMS & AFMC
Molecules 3D Images: www.proteopedia.org
RNA, DNA, Ribosome, Hemoglobins ... Proteins 3DEncyclopedia
Class 1 to Class 12 www.MeritNation.com
Free NCERT Solutions, Test Papers, Lessons,Animations, Videos, Puzzle
Measure Leaf Area www.licor.com/areameters
Rapid Leaf Area Measurements for Growth andPlant Canopy Research.
Natural Ventilation www.gal-ventilation.com
High-Performance Roof Ventilators & Louvers,Engineering & CFD
Plant Stem Cells www.labosuisse.com
The innovation in dermocosmetics Swiss patentedby Labo.
