Biology, Seventh Edition
Solomon • Berg • Martin
Chapter 31
Plant Structure,
Growth, and
Differentiation
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Plants
• Herbaceous
–In temperate climates, aerial parts
die back
–Annuals, biennials, perennials
• Woody
–In temperate climates, aerial parts
persist
–Perennials
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Annuals
• Grow, reproduce, and die in one
year or less
–Corn
–Geranium
–Marigold
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Duckweeds, with Wolffia on frog’s back
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Biennials
• Take two years to complete their
life cycles before dying
–Carrot
–Queen Anne’s lace
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Perennials
• Have the potential to live for more
than two years
–Asparagus
–Oak trees
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Eucalyptus regnans
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Life history strategies
• Long-lived trees compete
successfully against smaller
plants in favorable environments
(e.g., tropical rain forests)
• Small, short-lived plants thrive in
unfavorable environments (e.g.,
deserts after a rainy spell)
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Vascular plant body
• Root system
–Generally underground
–Obtains water and dissolved
nutrient minerals
–Anchor plant in place
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
The plant body:
Arabidopsis
thaliana
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Vascular plant body, cont.
• Shoot system consists of
–A vertical stem bearing leaves
(organs of photosynthesis)
–Reproductive structures (flowers
and fruits in flowering plants)
–Buds (undeveloped embryonic
shoots that develop on stems)
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Vascular plant body, shoot
system, cont.
• Generally aerial
• Obtains sunlight and exchanges
gases, such as CO2, oxygen, and
water vapor
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Vascular plant body, cont.
• Plant body is composed of
–Ground tissue system
–Vascular tissue system
–Dermal tissue system
• Although separate organs exist,
tissue systems are integrated
throughout plant body
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
The three tissue systems in the plant body
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Ground tissue system
• Parenchyma tissue
• Collenchyma tissue
• Sclerenchyma tissue
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Parenchyma
cells
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Collenchyma cell
Schlerenchyma
cells
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Parenchyma tissue
• Composed of living parenchyma
cells with thin primary cell walls
• Functions
–Photosynthesis
–Storage
–Secretion
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Collenchyma tissue
• Consists of collenchyma cells
with unevenly thickened primary
cell walls
• Function is to provide flexible
structural support
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Sclerenchyma tissue
• Composed of sclerenchyma cells
(sclereids or fibers) with
–Primary cell walls
–Secondary cell walls
• Function is to provide structural
support, although Sclerenchyma
cells are often dead at maturity
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Parenchyma
cell type
Sclerenchyma
cell type
Collenchyma
cell type
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Vascular tissue system
• Conducts materials throughout
plant body
• Provides strength and support
• Consists of
–Xylem
–Phloem
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Biology, Seventh Edition
Tracheid (xylem cell
CHAPTER 31 Plant Structure, Growth, and Differentiation
Sieve tube element
Vessel
element
(xylem cell)
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Phloem tissue
Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Vascular tissue system, cont.
• Xylem
–Complex tissue conducting water
and dissolved nutrient minerals
–Conducting cells are tracheids and
vessel elements
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Vascular tissue system, cont.
• Phloem
–Complex tissue conducting sugar in
solution
–Conducting cells are sieve tube
elements; they are assisted by
companion cells
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Tracheid
Vessel element
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Sieve tube
element
Companion
cell
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Dermal tissue system
• Outer protective covering of the
plant body
• Consists of
–Epidermis
–Periderm
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Dermal tissue system, cont.
• Epidermis
–Complex tissue covering
herbaceous plant body
–Epidermis of aerial parts secretes a
waxy cuticle to reduce water loss
–Stomata permit gas exchange
–Trichomes (outgrowths or hairs)
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Dermal tissue system, cont.
• Periderm
–Complex tissue covering woody
parts of plant body in woody plants
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Epidermal
cell
Guard cell
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Trichome
Cork cell
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Growth in plants versus animals
• Localized in meristems
• Involves
–Cell division
–Cell elongation
–Cell differentiation
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Primary growth
• Increase in stem or root length
• Occurs in all plants
• Secondary growth
• Increase in stem or root girth
• Localized
• Typically occurs in long cylinders of
meristematic cells throughout length
of older stems and roots
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Apical meristems
• Localized
–At tips of roots
–At tips of shoots
–Within buds of stems
• Activity herein results in primary
growth
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
A root tip
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
• Lateral meristems
• Vascular cambium
• Cork cambium
• Responsible for secondary
growth
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Longitudinal section through shoot apex
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Biology, Seventh Edition
CHAPTER 31 Plant Structure, Growth, and Differentiation
Secondary growth
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