1. Plant Form and Function
Chapter 35
Structure, Growth, and Development

2. The plant body has a hierarchy of organs, tissues, and cells
There are three basic plant organs:
Roots
Stems
Leaves

3. Roots Fibrous Roots Tap Roots
Roots are multicellular organs with important functions:
Anchoring the plant
Absorbing minerals and water
Storing organic nutrients
Fibrous Roots
Tap Roots
Micorrhizae – fungus that forms a symbiotic relationship with some plants

4. Shoot System: Stems and Leaves
Reproductive shoot (flower)
Apical bud
Node
Internode
Apical
bud
Stems – function primarily to display the leaves.
Terminal Bud – area of growth at the top end of stem
Axillary Buds – area of growth located in the V area between the leaf and the stem (branches)
Leaves – main photosynthetic organ in plants
Shoot
system
Vegetative
shoot
Blade
Leaf
Petiole
Axillary
bud
Stem
Taproot
Lateral
branch
roots
Root
system

5. There are three basic groups of plant tissues:
Dermal Tissue
Single layer of closely packed cells
Protects plant against water loss and invasion by pathogens and viruses
Cuticle – waxy layer in leaves
Vascular Tissue
Xylem and phloem
Ground Tissue
Any tissue that’s not Dermal or Vascular tissue
Pith – ground tissue located inside vascular tissue
Cortex – ground tissue located outside the vascular tissue

6. Plants have 5 major types of cells:
Parenchyma
Most abundant
present throughout plant
most metabolism (photosynthesis)
Collenchyma
Grouped in cylinders, supports growing parts of plant
Strings of celery (vascular tissue) is supported by collenchyma cells
Sclerenchyma
Exists in parts of the plant that are no longer growing
Tough cell walls utilized for support
Xylem
Phloem

7. Parenchyma cells in Elodea leaf, with chloroplasts (LM) 60 µm
Fig a
Figure Examples of differentiated plant cells
Parenchyma cells in Elodea leaf,
with chloroplasts (LM)
60 µm

8. Collenchyma cells (in Helianthus stem) (LM)
Fig b
5 µm
Figure Examples of differentiated plant cells
Collenchyma cells (in Helianthus stem) (LM)

9. Sclereid cells in pear (LM)
Fig c
5 µm
Sclereid cells in pear (LM)
25 µm
Cell wall
Figure Examples of differentiated plant cells
Fiber cells (cross section from ash tree) (LM)

10. Vessel Tracheids Pits Tracheids and vessels (colorized SEM)
Fig d
Vessel
Tracheids
100 µm
Pits
Tracheids and vessels
(colorized SEM)
Figure Examples of differentiated plant cells
Perforation
plate
Vessel
element
Vessel elements, with
perforated end walls
Tracheids

11. longitudinal view (LM) 3 µm
Fig e
Sieve-tube elements:
longitudinal view (LM)
3 µm
Sieve plate
Sieve-tube element (left)
and companion cell:
cross section (TEM)
Companion
cells
Sieve-tube
elements
Plasmodesma
Sieve
plate
Figure Examples of differentiated plant cells
30 µm
10 µm
Nucleus of
companion
cells
Sieve-tube elements:
longitudinal view
Sieve plate with pores (SEM)

12. Meristems generate cells for new organs
Apical meristems
Are located at the tips of roots and in buds of shoots.
Sites of cell division that allow plants to grow in length (primary growth)
Lateral meristems
results in growth which thickens the shoots and roots (secondary growth)

13. Primary Growth lengthens roots and shoots
Cortex
Vascular cylinder
Epidermis
Key
to labels
Zone of
differentiation
Zone of cell division
Includes apical meristem
New cells produces
Root cap is located in root
Zone of elongation
Elongation of cells
Zone of maturation
Cell differentiation
Cell become functionally mature
Root hair
Dermal
Ground
Vascular
Zone of
elongation
Apical
meristem
Zone of cell
division
Root cap
100 µm

14. Secondary Growth add girth to stems and roots in woody plants
Two lateral meristems
Vascular cambrium
Produces secondary xylem (wood)
Secondary phloem
Cork cambrium
Produces tough covering that replaces epidermis early in secondary growth
Bark includes all the tissues outside the vascular cambrium.

15. Growth, morphogenesis, and differentiation produce the plant body
Morphogenesis – the development of body form and organization. This is the process of cell specialization

16. Resource Acquisition and Transport in Vascular Plants
Chapter 36

17. Transport occurs by: Short-Distance Long-Distance Diffusion
Active transport
Cotransport – the coupling of the steep gradient of one solute (H+) with a solute like sucrose
Long-Distance
Bulk flow – the movement of water through the plant from regions of high pressure to regions of low pressure
Aquaporins

18. Water Potential
Water potential is a measurement that combines the effects of solute concentration and pressure
Water flows from regions of higher water potential to regions of lower water potential
Water potential is abbreviated as Ψ and measured in units of pressure called megapascals (MPa)
Ψ = 0 MPa for pure water at sea level and room temperature

19. How Solutes and Pressure Affect Water Potential
Both pressure and solute concentration affect water potential
The solute potential (ΨS) of a solution is proportional to the number of dissolved molecules
Solute potential is also called osmotic potential
Pressure potential (ΨP) is the physical pressure on a solution
Turgor pressure is the pressure exerted by the plasma membrane against the cell wall, and the cell wall against the protoplast

20. Measuring Water Potential
Consider a U-shaped tube where the two arms are separated by a membrane permeable only to water
Water moves in the direction from higher water potential to lower water potential

21. (a) 0.1 M solution Pure water H2O ψP = 0 ψS = 0 ψP = 0 ψS = −0.23
Fig. 36-8a
(a)
0.1 M solution
Pure water
Figure 36.8a Water potential and water movement: an artificial model
H2O
ψP = 0 ψS = 0
ψP = 0 ψS = −0.23
ψ = 0 MPa
ψ = −0.23 MPa

22. The addition of solutes reduces water potential

23. (b) Positive pressure H2O ψP = 0 ψS = 0 ψP = 0.23 ψS = −0.23 ψ = 0 MPa
Fig. 36-8b
(b)
Positive pressure
Figure 36.8b Water potential and water movement: an artificial model
H2O
ψP = 0 ψS = 0
ψP = ψS = −0.23
ψ = 0 MPa
ψ = 0 MPa

24. Physical pressure increases water potential

25. (c) H2O ψP = 0 ψS = 0 ψP = ψS = −0.23 ψ = 0 MPa ψ = 0.07 MPa
Fig. 36-8c
(c)
Increased positive pressure
Figure 36.8c Water potential and water movement: an artificial model
H2O
ψP = 0 ψS = 0
ψP =   ψS = −0.23
0.30
ψ = 0 MPa
ψ = MPa

26. Negative pressure decreases water potential

27. Negative pressure (tension)
Fig. 36-8d
(d)
Negative pressure (tension)
Figure 36.8d Water potential and water movement: an artificial model
H2O
ψP = −0.30 ψS =
ψP = ψS = −0.23
ψ = −0.30 MPa
ψ = −0.23 MPa

28. Figure 36.8 Water potential and water movement: an artificial model
(b)
(c)
(d)
Positive pressure
Increased positive pressure
0.1 M solution
Negative pressure (tension)
Pure water
H2O
H2O
H2O
H2O
ψP = 0 ψS = 0
ψP = 0 ψS = −0.23
ψP = 0 ψS = 0
ψP = ψS = −0.23
ψP = 0 ψS = 0
ψP = ψS = −0.23
ψP = −0.30 ψS = 0
ψP = 0 ψS = −0.23
Figure 36.8 Water potential and water movement: an artificial model
ψ = 0 MPa ψ
= −0.23 MPa
ψ = 0 MPa
ψ = 0 MPa
ψ = 0 MPa
ψ = MPa
ψ = −0.30 MPa
ψ = −0.23 MPa

29. Vegetative Propegation
Types of Veg. Propagation
Description
Examples
Bulbs
Short Stems Underground
Onions
Runners
Horizontal Stems above ground
Strawberries
Tubers
Underground Stems
Potatoes
Grafting
Cut a stem and attach it to a closely related plant
Seedless Oranges

30. Tropical Tropisms tropism – turning response to a stimulus
Phototropism
Refers to how plants respond to light
Gravitropism
Refers to how plants respond to gravity
Thigmotropism
Refers to how plants respond to touch (IVY, strangler trees
Auxins
Responses are initiated by hormones. Major plant hormones belong to the class AUXINS

32. Table 39-1