Plant Tissues

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Plant Tissues

• Starr/Taggarts
• Biology
• The Unity and Diversity of Life, 9e
• Chapter 29

2
DMA
What characteristics of angiosperms and
gymnosperms allow them to be the dominant land
plants?
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AngiospermsThe Flowering Seed-Bearing Plants

• Flowers
• Coevolution with pollinators
• Insects
• Bats
• Birds
• Seed
• Ovary

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Key Concepts

• Angiosperms and gymnosperms dominate the plant
  kingdom
• These are seed-bearing vascular plants with
  complex above-ground structures and root systems
• These plants have three major categories of
  tissue systems ground, vascular, and dermal

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Overview of the Plant Body

• 3 tissue systems
• Ground
• Bulk of plant
• Vascular
• Conducting tissues
• Distribute water and solutes
• Dermal
• Covers and protects

Fig. 29.2, p. 500
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Basic Definitions

• Stem region of the plant containing the
  following tissues
• meristem, support, vascular, and buds (buds give
  rise to new stems, leaves, flowers)
• Leaf a chlorophyll containing tissue that is the
  major region of photosynthesis
• Root typically found below ground, responsible
  for
• Water and nutrient absorption, anchoring the
  plant, food storage

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Types of Plant Tissues-Simple

• Parenchyma
• Storage
• Support
• Mesophyll
• Photosynthetic
• Collenchyma
• Flexible support for primary tissues

• Sclerenchyma
• Support
• Protects seeds
• Lignin impregnated
• Fibers
• Sclereids

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Types of Plant Tissues-Simple
Fig. 29.6, p. 502
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Complex Tissues

• Vascular
• Xylem
• Water
• Dissolved ions
• Mechanical support
• Phloem
• Conducts sugars and solutes

• Dermal
• Epidermis
• Cuticle
• Waxes
• Cutin
• Restriction of water loss
• Stem and leaf epidermis
• Guard cells
• Stoma
• Periderm

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Dicots and MonocotsSame Tissues, Different
Features

• Dicot
• Two cotyledons
• 4 - 5 floral parts or multiples
• Netlike array of leaf veins
• 3 pores in pollen grain
• Vascular bundles in a ring in stem

• Monocots
• One cotyledon
• 3 floral parts or multiples
• Parallel veins in leaves
• 1 pore in pollen grains
• Vascular bundles throughout ground tissue of stem

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In seeds, two cotyledons (part of the embryo)
In seeds only one cotyledon
Usually four or five floral parts (or
multiples of these)
Usually three floral parts (or multiples of
three)
Usually a netlike array of leaf veins
Usually a parallel array of leaf veins
Basically, three pores of furrows in pollen grain
Basically, one pore or furrow in pollen grain
vascular bundle
Vascular bundles distributed ground tissue of
stem
Vascular bundles arrayed as a ring in stem
Fig. 29.10, p. 503
DICOTS
MONOCOTS
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vessels in xylem
meristematic cell
epidermis
cortex
vascular bundle
pith
fibers in phloem
Ring of vascular bundles dividing ground tissue
into cortex and pith
Stem, transverse section enlargement of a
vascular bundle shown at right
Sieve-tube members and companion cells in phloem
Fig. 29.13a, p. 505
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sheath of thick-walled Sclerenchyma cells around
mature vascular bundle
vessel in xylem
air space
epidermis
ground tissue
vascular bundle
Sieve-tube member in phloem
companion in phloem
Vascular bundles distributed throughout ground
tissue
Stem, transverse section enlargement of a
vascular bundle shown at right
Fig. 29.13b, p. 505
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Meristems Where Tissues Originate

• Shoot Apical Meristem
• Lateral Meristem
• Root Apical Meristem

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Primary Structure of Shoots

• Apical meristem a mass of self-perpetuating
  cells responsible for primary growth at root and
  shoot tips
• Procambium gives rise to vascular tissue
• Protoderm gives rise to the epidermis
• Ground meristem gives rise to the cortex or part
  of the ground tissue

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Types of Stems

• Stems can be either classified as part of
  monocots or dicots.
• Stems can also be classified as herbaceous or
  woody.
• Herbaceous flexible, one season growth
• Woody inflexible, multiple seasons of growth

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Different Types of Leaves
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UPPER EPIDERMIS
cuticle of upper epidermis
leaf vein (one vascular bundle inside the leaf)
xylem
PALISADE MESOPHYLL
phloem
Water and dissolved mineral ions move from roots
into stems, then into leaf vein (blue arrow)
SPONGY MESOPHYLL
LOWER EPIDERMIS
cuticle-coated cell of lower epidermis
Products of Photosynthesis (pink arrow) enter
vein and are transported to stems, roots)
one stoma (opening across the epidermis)
Oxygen and water vapor escape from the leaf
through stomata
Carbon dioxide from the surrounding air enters
the leaf through stomata
Fig. 29.16, p. 507
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The Fine Structure of Leaves

• Cuticle covers epidermis
• Stomata
• Mesophyll (photosynthetic)
• Veins (vascular bundles)

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Stomata

• Stomata are leaf openings that are regulated by
  guard cells.
• Why are stomata typically found on the underside
  of leaves?

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Root Systems

• Taproot Root System (most dicots)
• Primary root gives rise to lateral roots
• Youngest lateral roots closest to root tips
• Fibrous Root System (most moncots)
• Primary root short-lived
• Adventitous roots arise from stem, lateral roots
  branch from these

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Fig. 29.17, p. 508
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Structure of Roots

• Epidermis
• Cortex ground tissue between epidermis and
  vascular bundles
• Vascular cylinder
• Endodermis outside the cortex, inside the
  pericycle
• Pericycle produces branch roots
• Phloem
• Xylem
• Pith parenchyma tissue at center of root

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fully grown root hair
VASCULAR CYLINDER
endodermis
pericycle
xylem
phloem
cortex
epidermis
Vessels have now matured root hairs and the
vascular cylinder are about to form
Cells elongate sieve tubes of phloem form
and mature xylems vessel members start to form
Most cells have stopped developing
Cells are dividing rapidly at apical and
primary meristems
Quiescent center (no cell division)
Fig. 29.18, p. 508
100 µm
root cap
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Secondary GrowthThe Woody Plants

• Annuals
• Non-woody
• One growing season
• Biennials
• Two growing seasons
• 1st roots, stems, leaves
• 2nd flowers, seeds, death
• Perennials
• Vegetative growth
• Seed formation
• Woody plants

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Trunk of a Redwood
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Activity of the Vascular Cambium

• Vascular cambium is a lateral meristem
• Secondary xylem forms on the inner face
• Secondary phloem forms on the outer face

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Secondary Growth in the Root

• Woody plant
• Vascular cambium forms secondary xylem and phloem

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A Look at Wood and Bark
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Early Wood, Late Wood, and Tree Rings

• Heartwood
• Center
• Xylem filled with metabolites
• Aromatic
• Sapwood
• Secondary growth between heartwood and vascular
  cambium
• Growth Rings
• Seasonal
• Hardwood (maple) and Softwood (pine)

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Hardwood - Oak