3. Leaves
- lateral outgrowth of the
stem
- flattened,expanded
- leaf primordia
- leaf buttress

4. Leaf Parts:
1. Petiole
- cylindrical part Sessile or apetiolated
- attaches blade to
the stem
Petiolated
2. Lamina or Blade
- flattened green
part

5. Monocot leaf
• Supported by leaf sheath
• Ligules and auricles
Functions:
1. protection from dirt
water

6. 3. Stipule
- two leaflike flaps of the
petiole
- dicot leaves
a. Stipulate – w/ stipule
b. Exstipulate – without
4. Midrib
- central vein
5. Veins
- conducting tissue of the
leaf
6. Veinlets
- secondary veins
7. Margin
- edge of the leaf

7. Simple leaf
- one blade or lamina
Compound leaf
- blade is divided into two or
more leaflets or (pinnae)
- petiolule
Rachis – continuation of the
petiole where the leaflets
are attached

8. Types of Compound Leaves
A. Pinnately Compound
- leaflets are arranged
laterally along the
rachis (featherlike
fashion)

9. 1. Simple Pinnate
a. Even pinnate
- each leaflet has a pair
b. Odd pinnate
- terminal leaflet has no
pair

10. 2. Bipinnate
- primary rachis branches
into secondary rachis that
bears the leaflets
3. Tripinnate
- with primary, secondary
and tertiary rachises

11. B. Palmately Compound
- leaflets radiate from a
common point
1. Unifoliate
- single leaflet at the
tip of the stalk
2. Bifoliate
3. Trifoliate
4. quadrifoliate

12. PHYLLOTAXY

13. Phyllotaxy
1. Alternate
- one leaf at each node
2. Opposite
- two leaves opposite
each other at each
node
3. Whorled/verticillate
- several leaves at equal
distance around the
node

14. 4. Spiral
- leaves arise
succeedingly around
the stem
5. Decussate
- two opposite leaves
at right angles to the
one below or above it

15. Shape

16. Margin

17. Leaf Venation

18. 2 Systems of Venation:
1. Reticulated/Netted
- main vein branches
- forms network
a. Pinnately netted
- main vein
- veins and veinlets
arise from the
midrib and ramify
throughout the lamina

19. b. Palmately netted
- principal veins arise at
one point at the base of
the leaf

20. c. Radiately netted
- principal veins radiate
at the tip of the petiole
Colocasiaesculenta (gabi)

21. 2. Parallel/Striate
Venation
- veins are parallel with
the midrib
- common in monocots
a. Radial Parallel
- parallel veins form
acute/right angles to
the midrib

22. Diagram of Dicot Leaf

24. Dicot Leaf Cross section

25. 1. Epidermis
- upper and lower
- single layer of cells
- derived from protoderm
Functions:
a. Protects leaf from dessication –(cuticle)
b. Abrasion
c. Prevents entry of fungi and bacteria
d. Regulates exchange of gases (Oxygen
and carbon dioxide

26. 1. Trichomes
- protection against water
loss
2. Stomata
- more stomata in lower
epidermis
- high temperatures
- high concentration of CO2
close stomata

27. 2. Mesophyll
- located between the upper and lower
epidermis
- dicots (2 distinct layers)
a. Palisade mesophyll
- arranged in compact columnar fashion
- most photosynthetic activity takes
place
b. Spongy mesophyll
- irregularly shaped
- prominent intercellular air spaces
- diffussion of carbon dioxide to other
parts of leaf

28. 3. Vascular bundle/Leaf Vein

29. 3.
xylem
- part that faces upper
surface of the leaf
phloem
- part that faces the lower
surface of the leaf
bundle sheath cells
- for added strength and
protection

30. Diagram of Monocot Leaf

31. Monocot leaf cross section

33. Internal Anatomy of Monocot Leaf
1. Upper epidermis
- covered with cuticle
- bulliform cells
- stomata present in upper and lower
epidermis
Guard cells monocot
- dumbbell in shape
Guard cells dicot
- kidney shaped
2. Mesophyll
- not differentiated into palisade and
spongy mesophyll

34. Pine leaf cross section
Cuticle
- much thicker
Epidermis
- multilayered
Mesophyll

36. Modified Leaves

37. Spines
- modified leaves or
modified stipules
- for protection

38. Tendrils
- slender, coiling
structures
- for support
- exhibit thigmotropism
(opposite side begins to
grow rapidly )

39. b
Bracts
- modified leaves at the
base of the flowers
- colored bracts for
attraction
ex. Poinsettia
bougainvilla

40. Uncutiniced leaves
- for absorption
ex. Digman

41. Expanded leaf like petiole
- for additional
photosynthesis
ex. Pomelo

42. Fleshy and succulent leaves
- for storage
ex. Sabila

43. Plantlets at the tip of the
leaves
- for reproduction
ex. kalanchoe

44. Insectivorous leaf
- for absorption