1. Plant Tissues

2. Angiosperms – flowering plants
The angiosperms are seed-bearing vascular plants
In terms of distribution and diversity, they are the most successful plants on Earth
The structure and function of this plant group help explain its success

3. Monocots and Dicots – same tissues, different features
1 cotyledon
2 cotyledons
4 or 5 floral parts
3 floral parts
Netlike veins
Parallel veins
3 pores
1 pore
Vascular bundles dispersed
Vascular bundles in ring

4. Flowering Plant Life Cycle
Diploid
Double fertilization
Meiosis
Meiosis
Haploid
Mitosis without cytoplasmic division
microspores
pollination
Two sperms enter ovule
Female gametophyte

5. Plant Life Histories Annuals complete life cycle in one growing season
Biennials live for two seasons; flowers form in second season
Perennials grow and produce seeds year after year

6. Meristems – Where Tissues Originate
Internode
Leaves
Axillary bud at node
Longitudinal section of terminal bud
Regions where cell divisions produce plant growth
Apical meristems
Lengthen stems and roots
Responsible for primary growth
Lateral meristems
Increase width of stems
Responsible for secondary growth

7. Apical Meristems Lengthen shoots and roots: StemAM and RootAM
activity at
meristems
Cells that form at apical meristems:
new cells
elongate
and start to
differentiate
into primary
tissues
protoderm  epidermis
ground meristem  ground tissues
procambium  primary vascular tissues

8. Lateral Meristems Increases girth of older roots and stems
Cylindrical arrays of cells
vascular cambium  secondary vascular tissues
periderm  cork cambium
thickening

9. Plant Tissue Systems Ground tissue system Vascular tissue system
EPIDERMIS
Ground tissue system
Vascular tissue system
Dermal tissue system
VASCULAR TISSUES
GROUND TISSUES
SHOOT SYSTEM
ROOT SYSTEM

12. Ground Tissue fills space b/t dermis & vascular
 Parenchyma: Primary metabolic function (photosynthesis)
Found in roots, stems & leaves
Least specialized, thin flexible walls, don’t divide unless specializing, respire, store food & water
Schlerenchyma: support w/ thick 2o well strengthened by lignin
Found in stems & leaves generally lack protoplasts
Very rigid cell wall, dead at maturity, cannot lengthen scaffolding “fibers” & “Sclereids”
Collenchyma: child support
Found in stems and leaves
Grow and elongate with stems and leaves they support, flexible in young parts of plant

13. Morphology of three simple tissue types
parenchyma
collenchyma
sclerenchyma

14. Parenchyma: A Simple Tissue
Comprises most of a plant’s soft primary growth
Cells are pliable, thin walled, many sided
Cells remain alive at maturity and retain capacity to divide
Mesophyll is a type of parenchyma that contains chloroplasts

15. Collenchyma: A Simple Tissue
Specialized for support for primary tissues
Cells are elongated, with walls (especially corners) thickened with pectin
Makes stems strong but pliable
Cells are alive at maturity

16. Sclerenchyma: A Simple Tissue
Supports mature plant parts
Protects many seeds
Cells have thick, lignified walls and are dead at maturity
Two types:
Fibers: Long, tapered cells
Sclereids: Stubbier cells

17. Made up of only one type of cell
Simple Tissues
Made up of only one type of cell
Parenchyma
Collenchyma
Sclerenchyma

18. Composed of a mix of cell types
Complex Tissues
Composed of a mix of cell types
Xylem
Phloem
Epidermis

19. Vascular Tissue  
Phloem: Phood conduction, carries products of photosynthesis to non-photo cells
Found in roots, stems, leaves
Sieve cells, albuminous cells, companion cells, parenchyma
Gymnospersm: sieve, angiosperms, sieve-tube members, connected vertically by sieve plates
Alive at maturity
Xylem: provides water & ion transport from roots to leaves
Vessel elements, tracheids, fibers, wood parenchymal
tracheids & vessel members, thick w/ secondary wall with lignin
Dead at maturity
Seedless vascular & gymnosperms have tracheids w/ tapered ends
Angiospersm have both tracheids and vessel members wh are continuous

20. Xylem Conducts water and dissolved minerals
Conducting cells are dead and hollow at maturity
vessel member
tracheids

21. Phloem: A Complex Vascular Tissue
sieve plate
Transports sugars
Main conducting cells are sieve-tube members
Companion cells assist in the loading of sugars
sieve-tube
member
companion
cell

22. Epidermis: A Complex Plant Tissue
- Covers and protects plant surfaces
- Secretes a waxy, waterproof cuticle
- In plants with secondary growth, periderm replaces epidermis

23. Epiderm
protection, increase absorption area in roots, reduces H2O loss in stem & leaves,
Regulates gas exchange in leaves
Signaling between Plants and Pathogens

24. Shoot and Root Systems Shoot system produces sugars by photosynthesis
carries out reproduction
Shoot System
Root system
anchors the plant
penetrates the soil and absorbs water and minerals
stores food
Root System

25. Shoot and root systems are interdependent
water & minerals
sugar
SHOOT SYSTEM
ROOT SYSTEM

26. Shoot Development shoot apical meristem protoderm procambrium
ground meristem
cortex
procambrium
pith
primary xylem
primary phloem

27. Roots also have meristems

28. Leaf Gross Structure DICOT MONOCOT petiole axillary bud blade node
sheath
blade
node

29. Adapted for Photosynthesis
Leaves are usually thin
High surface area-to-volume ratio
Promotes diffusion of carbon dioxide in, oxygen out
Leaves are arranged to capture sunlight
Are held perpendicular to rays of sun
Arrange so they don’t shade one another

30. Leaf Structure UPPER EPIDERMIS cuticle PALISADE MESOPHYLL xylem SPONGY
phloem
LOWER
EPIDERMIS
CO2
one stoma O2

31. Mesophyll: Photosynthetic Tissue
A type of parenchyma tissue
Cells have chloroplasts
Two layers in dicots
Palisade mesophyll
Spongy mesophyll

32. Collenchyma
Parenchyma

33. Leaf Veins: Vascular Bundles
Xylem and phloem – often strengthened with fibers
In dicots, veins are netlike
In monocots, they are parallel

34. Internal Structure of a Dicot Stem
- Outermost layer is epidermis
- Cortex lies beneath epidermis
- Ring of vascular bundles separates the cortex from the pith
- The pith lies in the center of the stem

35. Internal Structure of a Monocot Stem
The vascular bundles are distributed throughout the ground tissue
No division of ground tissue into cortex and pith

36. Dicots Monocots Ground tissue system Dermal tissue system
Vascular tissue
system
Dicots and Monocots have different stem and root anatomies

37. Stems
Monocot stems differ from dicot stems in that they lack secondary growth
No vascular cambium nor cork cambium
Stems usually uniform in diameter
Scattered vascular bundles (not in a ring like dicot stems)

38. The Translocation of Phloem
the process of moving photosynthetic product through the phloem
In angiosperms, the specialized cells that transport food in the plant are called sieve-tube members, arranged end to end to form large sieve tubes
Phloem sap is very different from xylem sap
sugar (sucrose) can be concentrated up to 30% by weight
Phloem transport is bidirectional
Phloem moves from a sugar source (a place where sugar is produce by photosynthesis or by the breakdown of sugars) to a sugar sink (an organ which consumes or stores sugar)
What are some organs which would be sugar sinks?
Transport in Plants: The Pressure Flow Model
Transpiration Pull

39. Root Systems

40. Root Structure Root cap covers tip Apical meristem produces the cap
Cell divisions and elongation at the apical meristem cause the root to lengthen
Farther up, cells differentiate and mature
root apical meristem
root cap

41. Primary Root Growth Root Cap
Secretes polysaccharide slime that lubricates the soil
Constantly sloughed off and replaced
Apical Meristem
Region of rapid cell division of undifferentiated cells
Most cell division is directed away from the root cap
Quiescent Center
Populations of cells in apical meristem which reproduce much more slowly than other meristematic cells
Resistant to radiation and chemical damage
Possibly a reserve which can be called into action if the apical meristem becomes damaged
The Zone of Cell Division - Primary Meristems
Three areas just above the apical meristem that continue to divide for some time
Protoderm
Ground meristem
Procambium
The Zone of Elongation
Cells elongate up to ten times their original length
This growth pushes the root further downward into the soil
The Zone of Maturation
Region of the root where completely functional cells are found

42. Internal Structure of a Root
Outermost layer is epidermis
Root cortex is beneath the epidermis
Endodermis, then pericycle surround the vascular cylinder
In some plants, there is a central pith

43. epidermis
endodermis
cortex
pericycle
root hair
phloem
xylem

44. Root Anatomy - Dicot Roots
Epidermis
Dermal tissue
Protection of the root
Cortex
Ground tissue
Storage of photosynthetic products
Active in the uptake of water and minerals
Endodermis
cylinder once cell thick that forms a boundary between the cortex and the stele contains the casparian strip,
Pericycle
found just inside of the endodermis
may become meristematic
responsible for the formation of lateral roots
Vascular Tissue
Xylem and Phloem
Root Anatomy - Monocot Roots
cylinder once cell thick that forms a boundary between the cortex and the stele even more distinct than dicot counterpart contains the casparian strip,
monocot roots rarely branch, but can, and this branch will originate from the pericycle
Forms a ring near center of plant
Pith
Center most region of root

45. Root Hairs and Lateral Roots
Both increase the surface area of a root system
Root hairs are tiny extensions of epidermal cells
Lateral roots arise from the pericycle and must push through the cortex and epidermis to reach the soil
Root of a single rye plant (fibrous system) measure and counted 6400 roots w/ 12.5 million root hairs = 250 km, dist from Memphis, TN to Atlanta, GA
new
lateral
root

46. Symplastic Movement
Movement of water and solutes through the continuous connection of cytoplasm (though plasmodesmata)
No crossing of the plasma membrane (once it is in the symplast)
Apoplastic Movement
Movement of water and solutes through the cell walls and the intercellular spaces
No crossing of the plasma membrane
More rapid - less resistance to the flow of water

47. Secondary Growth Occurs in perennials
A ring of vascular cambium produces secondary xylem and phloem
Wood is the accumulation of these secondary tissues, especially xylem

48. Secondary Growth
The Plant Body: Secondary Growth: The Vascular Cambium

49. Woody Stem periderm (consists of cork, cork cambium,
and secondary cortex)
secondary
phloem
HEARTWOOD
SAPWOOD
BARK
vascular cambium

50. Annual Rings Concentric rings of secondary xylem
Alternating bands of early and late wood
Early wood
Xylem cells with large diameter, thin walls
Late wood
Xylem cells with smaller diameter, thicker walls

51. Types of Wood Hardwood (oak, hickory) Softwood (pine, redwood)
Dicot wood
Xylem composed of vessels, tracheids, and fibers
Softwood (pine, redwood)
Gymnosperm wood
Xylem composed mostly of tracheids
Grows more quickly

52. Plant Nutrition: Nitrogen and Iron Deficiencies

53. Resources
Plants in Motion: