1. Plant Structure
Chapter 35

2. Angiosperms Monocots Seed one cotyledon (seed leaf)
Leaves parallel veins
Roots fibrous
Vascular tissue scattered
Flower parts 3’s or multiples of 3’s
Bulbs, grasses, grains, orchids

3. Angiosperms Dicots (eudicots) Seed with 2 cotyledon (seed leaf)
Leaves with network of veins
Taproot
Vascular tissue arranged in a ring
Flowers in groups of 4 & 5 or multiples
Annuals, trees, shrubs, roses, peas

5. Angiosperms

7. Organs
Root
Stem
Leaves

8. Angiosperms

10. Organs Root system Anchors the plant Absorbs nutrients Water & ions
Shoot system
Stems & leaves

11. Roots Tap root One large root with small roots Lateral root
Branched roots
Adventitious root
Root grows from another part of plant
Fibrous root
Mat of thin roots

12. Modified roots Prop roots Grow from stem, corn Aerial roots
Roots extend in air
Plant does not grow into dirt
Pneumatophores
Plant grows in water
Roots above water to get oxygen

13. Modified roots Parasitic roots Take nourishment from host plants
Food storage roots
Xylem of roots such as sweet potato
Water storage roots
Grow in water deprived areas
Buttress roots
Adds to stability,very large

14. Root

15. Shoot system Stem positions leaves Leaves-food production Node:
Leave attachment
Internode:
Area on stem between nodes

16. Stem (external) Axillary bud: Bud along stem may be a branch
Terminal bud:
Bud at end where apical meristem

17. Modified stems Shoots with diverse functions Stolons:
Such as “runners” of strawberry plants
Grow on the surface
Enable a plant to colonize large areas
Rhizomes: (iris)
Horizontal stems that grow underground.

18. Modified stems Tubers: (potatoes) Swollen ends of rhizomes
Food storage.
Bulbs: (onions, tulips)
Vertical, underground shoots
Swollen bases of leaves-store food.

20. Modified stems Tendrils: Grapes, ivy give support for climbing
Cladphylls:
Flattened modified stems
Cactus

21. Leaf (external) Extension of shoot apical meristem
Principle site of photosynthesis
Expand by cell enlargement
Not cell division
Growth stops at maturity
Blade (flattened)
Stalk (petiole) mostly eudicots

22. Leaf (external) Veins (vascular bundles) Found in leaf
Parallel in monocots
Network in eudicots
Many shapes & arrangements
Spiral, paired or whorled

23. Leaf (external) Simple leaves: One blade with indentations or teeth
Compound leaves:
Blade divided into leaflets

24. Modified Leaves Other functions. Tendrils (peas) to cling to supports
Spines of cacti for defense
Leaves modified for water storage
Brightly colored leaves that attract pollinators.

25. Modified Leaves

26. Modified leaves

27. Tissue types 1. Dermal tissue Epidermis (primary growth)
One cell layer thick
Outer protective layer
Cuticle wax cover-water loss
Periderm (secondary growth)
Replaces epidermis in woody plants

28. Trichomes Hair like growth Epidermis from shoot “fuzzy”
Keep surface cool
Minimize evaporation
Keep herbivores from eating (sticky surface)

29. Root hairs Extensions of epidermal cells Occur behind root tips
Increase surface area
Absorption

30. Tissue type 2. Vascular tissue Transport Xylem:
Water & dissolved minerals
Phloem:
Carbohydrates (sucrose)

31. Tissue type 3. Ground tissue Thin-walled parenchyma cells
Storage, photosynthesis, support
Pith:
Internal to vascular tissue
Cortex:
External to vascular tissue

32. Tissue type

33. Plant cells 1. Parenchyma cells Large vacuoles Thin walled 14 sides
Most common type of plant cell

34. Parenchyma Cells Perform most metabolic functions
Synthesize & stores various organic products.
Fleshy tissue of most fruit.

35. Parenchyma

36. Plant cells 2. Collenchyma cells Usually little longer than wide
Cell wall thickness varies
Support for organs
Allows stems to bend & not break

37. Collenchyma

38. Plant cells 3. Sclerenchyma cells Supporting elements of the plant
Thick secondary walls
Much more rigid
Cannot elongate
Plant regions-stopped lengthening.

39. Plant cells Lignin: Highly branch polymer Strengthens walls
Types sclerenchyma
Fibers:
Long cells grouped in strands (linen)
Sclereids:
Branched (pears, seed coats, nutshells)

40. Sclerenchyma cells

41. 4.Water-conducting cells
Xylem (water minerals, inner)
Vessel members (elements)
Continuous tubes
Hollow, dead cylindrical cells end to end
Tracheids
Dead cells that overlap each other
Tapered ends
Thick walled
Wood is secondary xylem

42. Xylem

43. 5. Sugar-conducting cells
Phloem (outer)
Sieve cells
Sieve-tube members (elements)
Conduct carbohydrates
Away from where formed
Sieve-tube more advanced

44. 5. Sugar-conducting cells
Companion cells:
Next to sieve-tube cells
Plasmodesmata:
Connection between cells

45. Phloem

46. Vascular tissue

47. Growth Meristems: Embryonic tissues Clumps of small cells
Dense cytoplasm & large nuclei
Similar to stem cells
One cell remains meristematic
Indeterminate
Give rise to other tissues

48. Meristems Apical meristems Cell division
Elongation of roots & stems (tips)
Primary growth

49. Meristems

50. Apical meristems Primary tissues Tissues resulting from primary growth
Primary plant body
Made up of primary tissues
Young soft shoots, roots
Some plants entire plant body

51. Root 4 regions in developing roots 1. Root cap Protects new cells
Moves through soil
Perception of gravity
Help root to bend down
Nitrogen fixing bacteria

52. Root 2. Region of division Area in center of root tip Apical meristem
Cells divide every hours
3. Region of elongation
Cells produced are longer than wider
4. Region of maturation (differentiation)

53. Root Epidermal cells: Root surface have thin cuticle Root hairs
Cortex:
Parenchyma tissue
Between epidermis & vascular tissue

54. Root Endodermis: Inner boundary of cortex thin layer Casparian strips:
Surround the endodermal cells
Water cannot pass through the strips

55. Root

56. Root

58. Root

59. Roots Stele: Tissues interior to endoderm Pericycle:
Layer of cells inside endoderm
Give rise to lateral or branched roots
Pith:
Center of root
Primary xylem form around the pith
Primary phloem form in groups near xylem

60. Root

61. Lateral roots

62. Root

63. Stem Primordia: Bulges produced by apical meristem
Leaves, other shoots, or flowers
Intercalary meristems:
Add more length at plant internodes
Corn

65. Fig
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66. Leaf Stomata: Tiny pores Gap between guard cells
Guard cells: Specialized epidermal cells
Regulate opening
Transpiration:
Evaporation of water

67. Leaf More stomata on lower epidermis Decrease water loss
Contain chloroplasts
Result from asymmetrical cell division

68. Leaf Surface covered with epidermis Cuticle Mesophyll: Ground tissue
Layer between the epidermis layers
Contains veins (vascular bundles)

69. Leaf Palisade mesophyll: Closest to upper epidermis
Tightly packed cells
Contains parenchyma with chloroplasts
Spongy mesophyll:
Loosely arranged
Contains air spaces

70. Leaf

71. Leaf

72. Secondary growth Secondary tissues: Lateral meristems
Vascular cambium (xylem-wood, phloem)
Cork cambium
Secondary growth-increases girth

73. Secondary growth Periderm: Protective layer replaces epidermis
Cork plus the cork cambium
Lenticels:
Raised areas in periderm
Areas for gas exchange

74. Secondary growth

75. Stem
Fig
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings