1. Monocot vs Eudicot

2. Internal Structure of Stems
Vascular bundles of xylem and phloem run through ground tissues of stems, leaves, and roots
The bundles conduct water, ions, and nutrients between different parts of the plant, and also function in support
vascular bundle
Multistranded, sheathed cord of primary xylem and phloem in a stem or leaf

3. Internal Structure of Stems
In herbaceous and young woody eudicot stems, a ring of vascular bundles divides ground tissue into cortex and pith
Monocot stems have vascular bundles distributed throughout ground tissue

4. Primary Structure: Eudicot Stem
Just take notice of the arrangement of the Vascular Bundles. This is an Alfalfa plant which is a eudicot.
Cortex- located between the vascular bundles and epidermis
Pith- located in the center of the stem, surrounded by the vascular bundles.
(these structures are unique to Eudicots

5. Primary Structure: Eudicot Stem
A Cross-section of an alfalfa stem. The cylindrical arrangement of vascular bundles is a characteristic of eudicot stems.
Figure 25.8 Primary structure of A a eudicot stem and B a monocot stem.
Fig. 25.8a.1, p. 402

6. companion cell in phloem
Primary Structure: Eudicot Stem
vessel in xylem
meristem cell
Figure 25.8 Primary structure of A a eudicot stem and B a monocot stem.
sieve tube in phloem
companion cell in phloem
Fig. 25.8a.3, p. 402

7. Primary Structure: Monocot Stem
Just take notice of the arrangement of the Vascular Bundles. This is a Corn stem which is a monocot.

8. Primary Structure: Monocot Stem
B Cross-section of a corn stem. The vascular bundles in monocot stems are not arranged in a cylinder.
Figure 25.8 Primary structure of A a eudicot stem and B a monocot stem.
Fig. 25.8b.1, p. 402

9. collenchyma sheath cell companion cell in phloem
Primary Structure: Monocot Stem
collenchyma sheath cell
air space
vessel in xylem
Figure 25.8 Primary structure of A a eudicot stem and B a monocot stem.
sieve tube in phloem
companion cell in phloem
Fig. 25.8b.3, p. 402

10. Primary Growth of a Stem
Most primary growth occurs by cell divisions of apical meristem in terminal buds (naked or encased in bud scales)
Meristem cells differentiate into dermal tissues, primary vascular tissues, and ground tissues
A lateral bud is a dormant shoot that forms in a leaf axil
Lateral buds give rise to branches, leaves, and flowers

11. Primary Stem Growth (Eudicot)
This is showing how the growth of the stem is equivalent to the elongation and differentiation of cells. Thus, one region eventually becomes differentiated and will appear as if it’s a totally different region after growth has occurred.

12. Primary Stem Growth (Eudicot)
immature leaf
apical meristem
A Shoot tip, tangential cut.
B Same tissue region later, after the shoot tip has lengthened above it.
Figure 25.9 Growth in the stem of Coleus, a eudicot. A–C Successive stages of this stem’s primary growth. D The micrograph shows a longitudinal cut through the stem’s center. The tiers of leaves in the photograph below it formed in this linear pattern of development.
pith
xylem
phloem
cortex
C Later still, different lineages of cells are differentiating
and forming complex tissues.
Fig. 25.9a-c, p. 403

13. Leaf Growth

14. Leaf Development A Shoot tip, tangential cut. immature leaf
apical meristem
pith
vascular tissues forming
lateral bud forming
epidermis forming
apical meristem
youngest immature leaf
immature leaf
B Same tissue region later, after the shoot tip has lengthened above it.
C Later still, different lineages of cells are differentiating
and forming complex tissues.
pith
cortex
phloem
xylem
Growth in the stem of Coleus, a eudicot.
A–C Successive stages of this stem’s primary growth.

15. A Closer Look at Leaves
Leaves are metabolic factories where photosynthetic cells make sugars
Leaves vary in size, shape, surface specializations, and internal structure

16. Similarities and Differences
Leaf shapes and orientations are adaptations that help a plant intercept sunlight and exchange gases.
A typical leaf has a flat blade and, in eudicots, a petiole (stalk) attached to the stem
Leaves of grasses and other monocots are flat blades, with a base that forms a sheath around the stem
Simple leaves are undivided; compound leaves have blades divided as leaflets

17. Leaf Forms: Eudicots and Monocots
petiole
axillary bud
blade
node
sheath
blade
stem
Common leaf forms of A eudicots and B monocots
node A B
Fig ab, p. 404

18. Simple and Compound Leaves
elliptic
palmate
lobed
pinnatisect
C simple leaves and D compound leaves D
acuminate odd pinnate
elliptic odd pinnate
lobed odd bipinnate
Fig cd, p. 404

19. Fine Structure
Leaves contain mesophyll and vascular bundles between their upper and lower epidermis
A leaf’s internal structure is adapted to intercept sunlight and to enhance gas exchange
Many leaves also have surface specializations

20. Leaf Cell Surface Specialization
Hairs on a tomato leaf: Lobed heads are glandular structures that secrete aromatic chemicals that deter plant-eating insects
Example of leaf cell surface specialization: hairs on a tomato leaf. The lobed heads are glandular structures that occur on the leaves of many plants; they secrete aromatic chemicals that deter plant-eating insects. Those on marijuana plants secrete the psychoactive chemical tetrahydrocannabinol (THC).

21. Epidermis Epidermis covers every leaf surface exposed to air
A translucent, waxy secreted cuticle slows water loss from the sheet-like array of epidermal cells
Water vapor and gases cross the epidermis at stomata
Shape changes of guard cells close stomata to prevent water loss, or open stomata to allow gases to cross

22. Mesophyll
Mesophyll consists of photosynthetic parenchyma with air spaces between cells that allow gas exchange
Plasmodesmata connect the cytoplasm of adjacent cells
In leaves oriented perpendicular to the sun, mesophyll is arranged in two layers: palisade and spongy mesophyll
Monocot leaves that grow vertically intercept light from all directions; their mesophyll is not divided into two layers

23. Veins: The Leaf’s Vascular Bundles
Leaf veins are vascular bundles of xylem and phloem, typically strengthened with fibers
In eudicots, large veins branch into a network of minor veins embedded in mesophyll; in monocots, veins are similar in length and run parallel with the leaf’s long axis
vein
A vascular bundle in the stem or leaf of a plant

24. Eudicot and Monocot Leaves

25. Anatomy of a Eudicot leaf1
epidermis
palisade mesophyll 3 4
spongy mesophyll
xylem 5
vascular tissue
phloem
stomata 2
Anatomy of a eudicot leaf
Fig , p. 405