1. Chapter 35 Plant Structure, Growth and Development

2. Plants
Are very plastic in their body forms. They can’t move, so they adapt the growth and structure of their bodies instead.

3. Case in Point

4. Chapter focus Plant structure and growth
Warning – many terms or vocabulary words
Warning – many diagrams
Focus – structure, function, located next to ….

5. Question ?
What heading can be given to the following groups of words?

6.
Lettuce
Peas
Beans
Rhubarb
Apples
Oranges

7. Question ?
What is a vegetable?
What is a fruit?

8. Vegetables
Lettuce
Rhubarb
Fruits
Peas
Beans
Apples
Oranges

9. Point Plants have tissues and organs too, just like animals.
Asexual organs (vegetables)
Sexual organs (fruits)

10. Asexual Organs
1. Stem
2. Leaf
3. Root

11. Stem
The main body of the portion above ground of a tree, shrub or herb.
The ascending plant axis.
Have buds.

12. Stem Functions Support of other plant organs. Ps.
Storage (water and food).

13. Modified Stems
1. Rhizomes
2. Stolons
3. Tubers
4. Tendrils

14. Rhizome An elongated underground horizontal stem.
Ex: Iris, many grasses

15. Stolon An elongated above-ground horizontal stem.
Ex: Strawberries Airplane Plant

16. Tuber A much-enlarged, short, fleshy underground stem tip.
Ex: Dahlia, Potato

17. Leaf Lateral outgrowths of the stem axis.
Primary photosynthetic organs.
Function:
Photosynthesis
Storage

18. Leaf Modifications 1. Tendrils: for support 2. Bulbs: for food storage
Ex: Peas
2. Bulbs: for food storage
Ex: Onion
3. Insect Catching Ex: Carnivorous Plants
4. Flowers: thought to be modified leaves.

19. Other Modifications of Leaves
Tendrils
Spines
Succulent Leaves
Bracts

20. Root The descending axis of a plant, normally below ground. Functions:
Anchorage.
Absorption of water and minerals.
Storage.

21. Root Types Taproot - one main root.
Ex: carrot
Fibrous Roots - many small roots of equal size.
Ex: grass roots

22. Other Root Types

23. Sexual Organs
1. Flowers
2. Fruits
3. Seeds

24. Flowers Modified leaves grouped together on a stem.
Sexual reproductive organs.
Function:
Sexual Reproduction

25. Fruit A mature ovary, sometimes including other floral parts.
Function:
Seed dispersal
Seed protection

26. Fruits

27. Seed Mature ovule containing the embryo and nutrient tissues.
Function:
Dispersal unit in sexual reproduction.

28. Plant Cell Types
Differentiated by the type and thickness of the cell wall.
1. Parenchyma (soft tissue)
2. Collenchyma (glue tissue)
3. Sclerenchyma (hard tissue)

29. Parenchyma Cells Primary wall only. Thin cell wall. Alive when mature,
“typical" plant cell.

30. Functions Ps
Storage
"Filler" cells
Cell division (mitosis)

31. Collenchyma Primary wall only.
Wall is thickened, especially in the corners.
Alive when mature.

32. Function
Support of non-woody plant parts.
Ex: veins, stems.

33. Sclerenchyma Secondary wall present. Wall strengthened with lignin.
Dead when mature.

34. Sclerenchyma Types 1. Fibers 2. Sclereids 3. Tracheids
4. Vessel Elements

35. Fibers
Elongated thin cells used for support.
Ex: Hemp fibers

36. Sclereids Used for hard dense areas and support.
Ex: Nut shells, seed coats

37. Tracheids Spindle - shaped cells with pits in the cell walls.
Used for water transportation.
Vessel
Fiber

38. Vessel Elements
Wide stocky cells with pits in the side walls; lack end walls.
Used for water transportation.

39. Plant Tissues Can be named by several methods:
Ex: Cell Location Cell Origin Cell Function

40. Point
The same cell can have several tissue names depending on the criteria for naming.

41. Main Tissue Systems
1. Dermal
2. Vascular
3. Ground

42. Dermal Tissue Epidermis or "skin" of the plant.
Often has a cuticle, a waxy coating to prevent water loss.
Functions:
Prevent water loss.
Water absorption (root hairs).

43. Vascular Tissue Made of Xylem and Phloem. Functions:
Transport and support
Xylem - Water
Phloem - Food

44. Xylem

45. Phloem

46. Phloem Sieve Cell – alive when functioning, but lacks a nucleus.
Companion Cell – alive, controls itself and the sieve cell.

47. Ground Tissue Tissue between the dermal and the vascular tissues.
Functions:
"Filler" tissue Ps
storage
support

48. Question ?
How does plant growth and animal growth differ ?

49. Animals Whole organism increases in size.
Determinant Growth: grow to a certain size, then stop.

50. Plants Growth in specialized areas only.
Indeterminant Growth: grow as long as they live because the specialized areas remain embryonic.

51. Plant Meristems
Perpetual embryonic regions.
Zones for cell division.

52. Meristem Types 1. Apical growth in length. Primary growth.
2. Lateral/Cambiums growth in diameter. Secondary growth.

53. Comment
Some tissues like Xylem may be Primary or Secondary depending on which meristem produced the cell.
Ex:
Primary xylem
Secondary xylem

54. Apical Meristem Types
1. RAM – Root Apical Meristem: primary growth of roots.
2. SAM – Shoot Apical Meristem: primary growth of shoots.

55. RAM Located at the tip of each growing root.
Protected from the soil by the Root Cap.
RAM

56. Root Cap
Protects RAM.
Secrets a polysaccharide lubricant for root growth.

57. Primary Root Zones 1. Cell Division - cells small and embryonic.
2. Cell Elongation - cells elongate and start to mature.
3. Cell Differentiation - cells mature into final cell types.

59. Root Hairs
Extensions of the epidermis to increase surface area for water absorption.
Not a true tissue.
Comment - root hairs are very delicate and must be continually replaced.

60. Root Hairs

61. RAM - Primary Tissues
1. Protoderm
2. Procambium
3. Ground Meristem

62. Protoderm
Will mature into the epidermis and root hairs.

63. Procambium Stele Matures into the vascular tissues of the stele: Xylem
Phloem
Pericycle – site of branch roots

64. Ground Meristem Matures into the ground tissues:
Cortex – storage tissue
Endodermis – second skin around the stele that controls the movement of materials into the stele.

65. Epidermis
Cortex
Stele

66. Endodermis
Pericycle
Xylem
Phloem

67. Branch Roots Originate from the pericycle.
Burst their way to the outside.

68. SAM Produces 1. Protoderm 2. Procambium 3. Ground Meristem
Comment – these tissues mature into the same things as seen in RAM.

69. SAM Differences No "root" cap.
Produces leaves as stem out-growths at the nodes.
Has buds.

71. Buds Apical Meristems protected by modified leaves or bud scales.
Axillary Buds

72. Branch Stems Develop from axillary meristems or axillary buds.
"External" development.

73. Leaves
Stem outgrowths for Ps.
Leaf Morphology:
1. Gross
2. Fine

74. Gross Morphology Blade - the flattened portion of a leaf.
Petiole - stalk of a leaf.

75. Axillary Buds
Blade
Petiole

76. Blade/Leaf Types
Simple - 1 blade.
Compound - Several blades.

77. Nodes and Internodes
Node - stem area where a leaf and bud are attached.
Internode - stem area between nodes.

78. Nodes }
Internode

79. Fine Morphology The tissues within a leaf. 1. Upper Epidermis
2. Mesophyll
3. Lower Epidermis
4. Veins

80. Upper Epidermis Cuticle present. Usually 1 cell layer thick.
Cells w/o chloroplasts .
Function: protects the mesophyll.

81. Mesophyll 1. Palisade upright cells.
2. Spongy loosely organized cells with air spaces.
Function: major sites for Ps.
Epidermis
Epidermis

82. Lower Epidermis Cuticle present. Usually 1 cell layer.
Cells w/o chloroplasts.
Stomata present for gas exchange.

83. Stomata (mouth)
Regulated by Guard Cells which have chloroplasts.

85. Vein Structure Xylem: dorsal Phloem: ventral
Often surrounded by bundle sheath cells for support.

86. Xylem
Phloem
Bundle Sheath Cells
Collenchyma

87. Stem Vascular Tissue
Eudicots – vascular bundles join together to make a ring. Often have secondary growth.
Monocots – vascular bundles are scattered. No true secondary growth.

89. Secondary Growth Growth in diameter.
Growth from lateral meristems or cambiums.

90. Cambium Types 1. Vascular – produces xylem and phloem.
2. Cork – produces “cork”.

91. Vascular Cambium Location: between primary xylem and phloem.
Produces: secondary xylem and phloem.

92. Fibers
Phloem
Vascular Cambium
Xylem
Fibers

93. Vascular Cambium: Cell Maturation
Internal  xylem
External  phloem
The VC pushes the xylem and phloem apart from each other.

95. Result Newest xylem is next to the cambium.
Oldest xylem is in the center of stem.

96. Result Newest phloem is next to cambium.
Oldest phloem is under the epidermis.

97. Result Xylem accumulates over time.
Phloem is destroyed by the outward growth and must be replaced yearly.

98. Cork Cambium Location: Cortex (external to the VC). Produces: Cork
Comment – commercial cork is harvested from a Cork Oak.

99. Cork Cells Produced "outwardly" only.
Covered with suberin and are dead when mature.
Function – insulation and protection.

100. Epidermis
Cork Cambium
Fibers
Cortex
Phloem
Vascular Cambium
Xylem

101. Bark All tissues external to the VC. Includes:
Phloem (1 degree and 2 degree)
Cork
Cortex
Epidermis
Fiber cells

103. Wood Xylem tissue of a dicot stem.
Comment – monocots don’t have VC and technically don’t produce true “wood”.

104. Xylem Growth Springwood - Large cells Rapid growth
Summerwood - Small cells Slow growth

105. Annual Rings
Formed by the growth difference between springwood and summerwood.
Usually one produced per year.

106. Comment Ring size varies by climate and growing conditions.
Rings can be used to date wooden structures.

107. Summer Wood
Spring Wood
One Year’s Growth

110. Angiosperms Divided into two main types: 1. Eudicotyledons or Eudicots
2. Monocotyledons or Monocots
Cotyledons = seed leaves

111. Monocots vs. Eudicots 1. Seeds and embryos 2. Leaves 3. Stems 4. Roots
5. Pollen
6. Flowers

113. Seeds and Embryos Eudicots - no endosperm. - 2 cotyledons.
Monocots - endosperm cotyledon

114. Leaves
Eudicots – netted veins.
Monocots - parallel veins.

115. Stems Eudicots - ring pattern - vascular cambium
Monocots - scattered pattern no vascular cambium

116. Roots Eudicots - taproot. - xylem centermost tissue.
Monocots - fibrous roots pith centermost tissue.

117. Pollen
Eudicots – 3 openings
Monocots – 1 opening

118. Flowers
Eudicots – parts in 4's or 5's.
Monocots – parts in 3's.

119. How do plants make their bodies different?
By changes in growth, morphogenesis and differentiation.

120. Growth
Meristems give information to new cells on how they should develop.
Plane and symmetry of cell division
Orientation of cell elongation

121. Plane of Cell Division

122. Cell Expansion

123. Mophogenesis How cells organize into tissues and organs.
Determined by:
Positional information
Homeotic genes

124. Cell Differentiation
Regulation of transcription and translation to make specific proteins.
Often “keyed” by positional information.

125. Cell Differentiation

126. Example - Flowering
Flowering is a phase change from indeterminate growth to determinate growth.
Triggered by environmental or internal signals.
ABC model of organ identity genes.

127. ABC Model
The 4 flower parts are controlled by interaction of genes A, B and C in 4 layers of cells.

128. Model Sepals – Gene A only in the outermost or 4th layer
Petals – Genes A and B in the 3rd layer.
Stamens – Genes B and C in the 2nd layer.
Carpels – Gene C only in the centermost layer.

129. Model

130. Mutants – ABC model

131. African Violet Mutants
ABC active in 2nd layer
A only mutant

132. Summary Know the main organs of plants and their functions.
Know the main cell types or tissues in plants and their functions.

133. Summary Know the structural organization of stems, roots, and leaves.
Know the differences between eudicots and monocots.

134. Summary Know about meristems and how plants grow.
Know about growth, morphogenesis and differentiation in plant bodies.