Leaf histology
The Epidermis
Definition: A protective layer, typically formed of a single layer.
The leaf lamina
The epidermis
Scheme for description of the surface preparation
Items
Upper Epidermis
Drawing
1- Shape of Cells:
2- Anticlinal walls:
3- Cuticle:
4- Stomata:
5- Hairs:
6- Content:
Lower Epidermis
Drawing
1- Shape of Cells
Polygonal
isodiametric
Polygonal
axially elongated
2- Anticlinal walls
Straight
Beaded
Wavy
Strongly wavy
3- Cuticle
A transparent impermeable layer of waxes and fats to protect the
epidermal cells
Smooth
Striated
4- Stomata
4- Stomata
Definition:
It’s a type of epidermal structure.
Function:
Exchange of gases & transpiration.
CO2
Structure of stomata
•It consists of 2 guard cells (elliptical in shape) enclosing between
them an osteole (a lenticular space).
•Epidermal cells surrounding the stomata are called subsidiary
cells.
osteole
Subsidiary cells
Guard cell
Types of stomata
I. According to characters
of guard cells
II. According to characters &
arrangement of subsidiary
cells
1. Gymnospermous type
1. Diacytic type
(e.g. Pinus)
2.Graminaceous type
(e.g. grass)
3.Dicotyledonous type
2. Paracytic type
3. Anisocytic type
4. Anomocytic type
II) Acc. to characters & arrangement of subsidiary cells
1.Diacytic type (Caryophyllaceous):
Surrounded by 2 subsidiary cells.
Their long axes is perpendicular to that of the osteole.
e.g. Saponaria
Striated cuticle
Diacytic stomata (Saponaria)
Striated cuticle
Diacytic stomata (Saponaria)
2.Paracytic type (Rubiaceous):
Surrounded by 2 or more subsidiary cells.
 2 of which having their long axes parallel to that of the
osteole.
e.g. Thevetia
Paracytic stomata (Thevetia)
3.Anisocytic type (Cruciferous):
Surrounded by 3 or more subsidiary cells.
One of which is distinctly smaller than others.
e.g. Eruca
Anisocytic stomata (Stramonium)
Striated
cuticle
Anisocytic stomata
4.Anomocytic type (Ranunculaceous):
Surrounded by varying number of subsidiary cells.
Have no special arrangement.
e.g. Lactuca
Beaded anticlinal wall
Anomocytic stomata (Digitalis)
Surface without stomata (upper surface of thevetia)