Plant kingdom
Monocot vs. Dicot
• Angiosperms (flowering plants) are divided
into monocots and dicots
• As the zygote grows into the embryo, the first
leaves of the young plant develop and are called
cotyledons (seed or embryonic leaves)
• Monocots have one cotyledon (corn).
• Dicots have two cotyledons (bean).
• There are several differences between
monocots and dicots
Difference 1:
• Number of seed leaves (or cotyledon)
Monocots
One seed leaf
vs
Dicots
Two seed
Monocot vs. Dicot
• Number of cotyledons: one vs. two
Difference 2:
Monocots and dicots differ in the arrangement of veins,
the vascular tissue of leaves
• Leaf venation pattern:
• Monocot is parallel
• Dicot is net pattern
Leaves
Monocot versus Dicots
Base of a Monocot
Leaf: Note the Sheath
which connects the
Blade to the Stem
Typical Dicot Leaf
with Reticulate
(Net) Venation
Which is which?
A is _____________
B is __________
Cross section of a
monocot leaf
Cross section of a
dicot leaf
Dicot. Leaves
Monocot leaves
1- Mesophyll
Differentiated into
palisade and spongy
parenchyma
not differentiated into
palisade and spongy
cells.
2- Vascular
tissues
V.B. open
V.B. closed (don’t
contain cambium)
The bundle sheath
parenchymatous
The bundle sheath may
be parenchyma or
sclerenchyma or thick
walled parenchyma.
3- Supporting
tissues
Collenchyma cells
fibers (above and below
located below the upper the bundles).
and lower epidermis
opposite to the bundles.
Difference 3:
• Stem types:
– Monocot: Herbaceous
– Dicot: herbaceous or woody
• Vascular Bundles (transport vessels in plants)
Monocot
vs.
Dicot
Scattered throughout
Arranged in ring
stem
in stem
Dicot. Stem
Monocot. Stem
1- V.B. open
1- V.B. closed (don’t contain
cambium)
2- V.B. arranged in a single ring
arround a central region called
pith
2- V.B. large number, scattered
irregularly through the ground
tissue.
3- Cortex, M.R.s, pith, pericycle,
endodermis are well marked
3- Cortex, M.R.s, pith, pericycle,
endodermis are indistinguishable
4- hypodermis almost
collenchymatous
4- hypodermis mostly
sclerenchymatous
Plant Growth - Stems
• In most monocot stems, the vascular bundles are scattered
throughout the ground tissue, rather than forming a ring
Phloem
Xylem
Sclerenchyma
(fiber cells)
Ground
tissue
Ground tissue
connecting
pith to cortex
Pith
Epidermis
Key
to labels
Cortex
Epidermis
Vascular
bundle
Dermal
Vascular
bundles
Ground
1 mm
(a) Cross section of stem with vascular bundles forming
a ring (typical of eudicots)
Vascular
1 mm
(b) Cross section of stem with scattered vascular bundles
(typical of monocots)
Stems
Monocot versus Dicot
Cross Section of
Corn which is a
typical Monocot
Cross Section of a
typical Dicot Stem
Difference 4:
Fibrous roots:
In monocots mostly,
primary root dies,
replaced by new
roots from stem
Taproots:
Typical of dicots,
primary root forms
and small branch
roots grow from it
Roots – Structure and Development
Epidermis
Cortex
Monocot
Endodermis
Location of
Casparian strip
Primary phloem
Pericycle
Primary xylem
Pith
1250 µm
385 µm
Endodermis
Location of
Casparian strip
Endodermis
Eudicot
Primary xylem
Cortex
Primary phloem
Epidermis
Pericycle
48 µm
8 µm
Cross section
of a monocot
root
Cross
section of
a dicot root
Dicot root
Endodermis
The number of
xylem/phloem
strands
Pith
Monocot root
Casparian strips Casparian strips
Are deposited on Are deposited on
radial walls only the radial and
inner tangential
walls.
2-8
Very narrow or
absent
numerous
Always present
Difference 5:
• Flower Parts
Monocot
Multiples of 3
vs.
Dicot
Multiples of 4 or 5
Monocot vs. Dicot
• Flower parts:
• Monocot: in groups of three
• Dicot: in groups of four or five
Comparing Monocots vs. Dicots
FEATURE
MONOCOTS
DICOTS
Cotyledons
1
2
Leaf venation
parallel
Net pattern
Root system
Fibrous
Tap
In 3’s
In 4’s or 5’s
Scattered
Arranged in a
circle
Either
Number of
floral parts
Vascular
bundle position
Woody or
herbaceous
Herbaceous