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
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
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
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
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