The document describes the anatomy and morphology of leaves. It defines leaves and their key parts like the lamina, petiole, stipules, and veins. It describes the different types of leaves including foliage leaves, bracts, and modified leaves. It also covers leaf arrangements, shapes, margins, bases, textures, and venation. The second half discusses microscopical leaf structures like the epidermis, cuticle, trichomes, stomata and their types. In summary, the document provides a comprehensive overview of leaf structure from the macroscopic to microscopic level.

2. The Leaf
(Latin: Folium)
• a lateral outgrowth or an appendage on the stem.
• possesses neither nodes nor internodes and buds
or lateral branches arise in its axil.
• Characters:
• - flattened form
• - thin texture
• - presence of chlorophyll
• - presence of veins

3. Leaf Morphology
Leaf lamina
Stipule
Petiole
Node
Internode
Axillary bud Stem
Axil

5. Types of Leaves
• 1- Cotyledons (seed-leaves):
• leaves of the embryonic plant in the seed
• for food storage
• i.e Almonds, Mustard and Beans
• 2- Prophylls (fore-leaves):
• first leaves born a branch
• simpler in form and structure from foliage leaves

6. • 3- Foliage leaves:
• The ordinary green leaves which carry on the
normal leaf functions.
• 4- Bracts:
• leaves having a flower in their axils
• usually simpler and smaller than ordinary leaves
• 5- Scale leaves:
• present on all subterraneran stems and on some
aerial ones
• thin, membranous and devoid of chlorophyll

7. • 6- Floral leaves:
• The variously coloured sepals and petals, also the
stamens and carpels
• no buds in their axils
• 7-Modified leaves:
• where the whole leaf or a part of it is modified to
carry out a certain function
• i.e a- tendrils for climbing as in Pea
• b- special traps for catching insects in
insectivorous plants as Drosera
• c- become succulent serving for storage of
water as Hyoscyamus muticus

8. Phyllotaxis
• It is the disposition of the leaves on the stem.
• The leaves being arranged on the stem in a
definite manner characteristic for each species
of plants.

9. Types of Phyllotaxis
Alternate Opposite Whorled
decussate

10. SessilePetioled
Leaf petiole (stalk)

11. Leaf base
Sheathed Ligulate
Stipulate Exstipulate Decurrent

12. Axil
Lamina
Leaf Apex
Vein
Mid-rib
Petiole
Stipule
Simple Leaf
Stem

13. Compound leaf

14. Forms of Compound leaves
Paripinnate Imparipinnate Palmate
Ternate Bipinnate

15. General description of the lamina of a
simple leaf
• general outline or shape
• Size
• Apex
• Base
• Margin
• Venation
• Surface
• texture

16. General outline or shape
• a- when the lamina has nearly the same width:
Filiform
(Fennel)
Acicular
(Pinus)
Tubular
(Onion)
Linear
(Grasses)
Oblong
(Cassia)

17. • b- when the lamina has the widest portion near the base:
Continued: General outline or shape
Lanceolate
(Long Buchu)
Ovate
(Boldo) Ensiform
(Eucaluptus)
Cordate
(Ipomea)
Sagitate
(Rumex)
Hastate
(Convolvulus)
Reniform
(Asarum)

18. Continued: General outline or shape
• c- when the lamina has the widest portion near the apex:
Obcordate
(Oxalis)
Obovate
(Dog Senna)
Spathulate
(Uva Ursi )
Lyrate
( Brassica)

19. Continued: General outline or shape
• d- when the lamina is symmetric or round:
Orbicular
(Nymphea)
Elliptical
(Pear)
Oval
(Boldo)

20. Size of the leaf
• the length from the base to the apex and the
broadest width
• it varies from tiny leaves (few millimeters) as
Savin to a very considerable size as banana
• In leaves used in medicine the doesn’t exceed
about 30 cm long as Digitalis
• Leaves vary in size on the same plant being bigger
at the base and becoming smaller as getting near
the apex

21. Apex of the leaf
Acute
(Hyoscyamus)
Acuminate
( Stramonium)
Obtuse
(Oval Buchu)
Recurved
(Short Buchu)

22. Margin of the leaf
Entire
(Senna)
Revolute
(Uva-Ursi)
Dentate
Serrate
(peppermint)
Spiny

23. Continued: Margin of the leaf
Bidentate
Crenate
(Digitalis)
Serrate Lobed

24. Base of the lamina
Symmetric Asymmetric
Decurrent

25. Venation
Parallel Reticulate

26. Surface of the lamina
Smooth
(Uva-Ursi)
Bunctate
(Buchu)
Glabrous
(Coca)
Pubescent
Hairy

27. Texture of the lamina
Membranous
Papery
Coriaceous
Succulent

28. Structure of the leaf
(Microscopical characters)

29. Epidermis:
• mainly a protective layer
• It occurs on the surface of plants and it is a complex tissue
consisting of epidermal cells, trichomes (hairs) and stomata
• Epidermal cells:
• It consists of a single layer of cells, but in some cases it may become
many layered as a result of division
• many layered epidermis often acts as water storage tissue and the
inner layer is often described as hypodermis
• tubular or lenticular with complete absence of intercellular spaces
except where the stomata occur

30. • appear in surface view polygonal:
- approximately isodiameteric in Dicots
- axially elongated in Monocots
Leaf epidermis in Dicots
(suface view)
Leaf epidermis in Monocots
(suface view)

31. • The anticlinal walls perpendicular to the surface:
- straight as Senna, Coca
- wavy as Belladonna
- beaded due to unequal thickening or thickenings
as Digitalis
• The epidermis outer walls are:
- convex
- cellulosic
- mostly thickened
- covered with cuticle
cuticle
epidermis

32. • Cuticle varies in thickness
- thin in shady plants as Digitalis
- thick in sunny regions plants
as Uva Ursi
Thin epidermal cuticle Thick epidermal cuticle

33. • Cuticle may be:
- smooth as Stramonium
- finely ridged appearing in surface view
striated as Belladonna
- formed mainly of cutin which is an aggregate
of modified fatty acids, partly combined with alcohols
• Epidermal cells are devoid of content
• in some cases may contain certain contents
• as: -calcium oxalate as Savin
• - calcium carbonate as Cannabis
• - diosmin as Buchu
• - mucilage as Senna

34. Trichomes or hairs
• Epidermal cells are sometimes extended
outwards forming projections of variable
shapes and sizes
• If they are short and conical papillae
and the epidermis described papillosed
these appear in surface view as circles in the
middle of the cells

35. • If the trichomes are long trichomes or
hairs
- The part embeded in the epidermis foot
- The free part body
- Covered with cuticle which may be smooth as
Hyoscyamous or warty as Senna
- Either of covering type as non-glandular
trichomes or of secretory function as
glandular trichomes
- Secretions may be volatile oils or oleo-resin

36. Trichomes or Hairs
Non-glandular Hairs
(covering type)
Glandular Hairs
(secretory function)
Uni-cellular multi-cellular multi-cellularUni-cellular

37. Multi-cellular
(formed of more than one cell)
Uni-cellular
(formed of more than one cell)
Unbranched
(Simple)
Ex: Senna
Branched
Ex: Crucierae
Unbranched
(Simple)
Branched
Non-glandular Hairs

38. Uni-seriate
(formed of one row)
Ex: Belladonna, Digitalis
Bi-seriate
(formed of two rows each
contain one cell (twin hair)
ex: Arnica flower, or more
cells ex: Calendula flower
Pluri-seriate
(formed of many
rows shaggy hair)
ex: Cumin
Non-glandular Hairs
multicellular unbranched (simple) hairs

39. Non-glandular Hairs
Multi-cellular branched hairs
Simple branched
(with uni-seriate body
ending in 2 branches)
ex: Tobacco
Stellate
ex: Boldo
Peltate
(scale hair)
Very short stalk
surrounded by plate
like structure of closely
joined cells ex: Olea
Balance hair
(T-shaped hair)
ex: Pyrethrum

40. c
Glandular hairs
I- Unicelluar (pear gland):
-not of common occurrence,
present in Piper.
- the foot is embedded in
the epidermis and the
swollen head is projecting
outside

41. II- Multicellular glandular hairs
- the most common type.
- consist of several cells and are classified into:
Uniseriate stalk Biseriate stalk and
biseriate head
(Compositae hair)
Pluriseriate stalk
and a head with
8 radiating cells
ex: Cannabis
Branched stalk
(Branched hair)
ex: Hyoscyamus
muticus

42. Uni-seriate stalk multi-cellular glandular hairs
Uni-cellular head Multi-cellular head
One-celled stalk
ex: Digitalis
2-3 celled stalk
ex: Belladonna,
Lavender

43. 1- celled stalk &
2-celled head ex:
Digitalis
1-or more celled stalk &
many celled ovoid head
ex: Hyoscyamous
Uni-seriate stalk multi-cellular glandular hairs
Uni-cellular head Multi-cellular head
very short: 1-
celled stalk & a
head of 8 radiating
cells ex: F: Labiatae
Labiacious hair

44. • These are openings in the
epidermis of stem and
leaves. They occur in both
surfaces or only on lower
surface.
• It’s a type of epidermal
structure of a great
diagnostic value
• Consists of:
- a central pore
- two similar cells; the
guard cells, kidney shaped
in Dicots while they are
dum-bell shaped in
Monocots
cStomata

45. • Stomatal number:
• The average number of stomata per square mm.
• It is of little value in distinguishing between closely
allied species
• Stomatal index:
Stomatal index = S x 100
E + S
• It is the percentage of number of stomata (S) in a
certain area to the sum of total number of epidermal
cells (E) and stomata together in same unit area.
• Stomatal index is constant for a given species

46. Types of Stomata
• 1-Moss type
- The guard cells, during
development, fuse with each
other by lysis of the separating
walls, thus the osteole becomes
surrounded by a single cell
Types of stomata according to characters of guard cells:

47. • 2- Gymnospermous:
- The guard cells are oval or elliptical and inclined to the
epidermis at an angle of approximately 45°.
• 3- Graminaceous:
- Stomata are usually rectangular in outline and the guard
cells are dumbell-shaped, thin walled ends and narrow
flat middle parts with outer and inner walls thickened.
- It is frequently with 2 subsudary cells lying parallel to
the long axis of the osteole

48. • 4- Dicotyledonous:
- Stomata are elliptical or circular in shape as seen in
surface view and surrounded by epidermal cells which
vary in characters and arrangement.
Types of stomata according to the characters and
arrangement of surrounding cells (subsidary cells):
1- Ranunculaceous (Anomocytic)
stomata:
-Equal celled type
- The stoma is surrounded by three to
five subsidary cells are of varying
number and almost of equal size
-ex: Digitalis leaves

49. • 2- Rubiaceous (Paracytic)
stomata:
- Paracytic stomata
- Parallel celled type
- The stoma is surrounded by two
or three subsidary cells , two of
which having their long axis
parallel to the axis of the osteole
- ex: Senna leaf, Coca leaf

50. • 3- Caryophyllaceous stomata:
- Diacytic stomata
- Cross-celled type
- The stoma is surrounded by
two or three subsidary cells
showing their long axis
perpendicular to the axis of
the osteole
- ex: Mentha leaf

51. • 4- Cruciferous stomata:
- Anisocytic stomata
- Unequal celled type
- The stoma is surrounded by
usually three or more subsidary
cells one of which is distinctly
smaller than the others
- ex: Solanaceous leaves

52. Mesophyll

53. • Palisade layer:
• formed of one or more layers of cylindrical
cells perpendicular to the epidermis with
narrow intercellular spaces which is usually
corrupted with the cortical tissues in the mid-
rib region.
• The upper palisade may form a continuous
layer as Senna or dis-continuous as
Hyoscyamus.

54. • Spongy tissue:
• formed of chlorenchyma with large irregular
cells with intercellular spaces.
• Hypodemis:
• The mesophyl is sometimes separated from
the epidrmis by one or more layers of cells
devoid of chlorenchyma called hypodermis
• This is a protective tissue or water, it may be
parechymatous, collenchymatous or
sclerenchymatous

55. • Cortical tissue:
• It is present in the mid-rib region
• Can be formed of parenchyma as in Belladonna,
or collenchyma as Uva Ursi.
• Endodermis:
• It is the inner-most layer of cortical tissue which
is usually indistinguishable in medicinal plants.

56. • Pericycle:
• present between the phloem and cortical
tissue
• mostly parenchyma but sometimes formed of
collenchyma as Digitalis
• Vascular system:

57. Bulliform cells
Bundle sheath cells with
chloroplasts
Parenchyma with
chloroplasts
Phloem
Xylem
Lower epidermis
Upper epidermis
Sclerified fibers
Collenchyma