Plant Tissues

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Plant Tissues

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

2
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

3
Key Concepts

• The simplest plant tissues are parenchyma,
  collenchyma, and sclerenchyma
• Complex plant tissues have two or more types of
  cells
• Each growing season, shoots and roots lengthen
  and thicken
• Primary and secondary growth occurs with each
  growing season

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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

• Shoots
• Stems
• Leaves
• Flowers
• Roots
• Absorb water and minerals
• Store food

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shoot tip (terminal bud)
lateral (axillary) bud
young leaf
flower
node
internode
EPIDERMIS
node
leaf
VASCULAR TISSUES
seeds (inside fruit)250
GROUND TISSUES
withered cotyledon
SHOOT SYSTEM
ROOT SYSTEM
primary root
root hairs
lateral root
root tip
Fig. 29.2, p. 500
root cap
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Regions Where Growth Occurs in Vascular Plants
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Meristems Where Tissues Originate

• Apical
• Transitional
• Protoderm
• Ground meristem
• Procambium
• Cambium
• Vascular
• Cork

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Types of Plant Tissues-Simple

• Parenchyma
• Soft tissue
• Primary growth
• Mesaphyll
• Photosynthetic
• Collenchyma
• Flexible support for primary tissues

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

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Fig. 29.5, p. 502
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Fig. 29.6, p. 502
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Complex Tissues

• Vascular
• Xylem
• Water
• Dissolved ions
• Mechanical support
• Phloem
• Conducts sugars and solutes
• Sieve-tube members
• Companion cells

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

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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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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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Primary Structure of Shoots

• Apical meristem
• Transitional meristems
• Vascular bundles
• Cortex
• Pith

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A Closer Look at Leaves

• Photosynthetic cells
• Deciduous
• Evergreen

• Blade
• Stalk
• Simple
• Compound (lobed)
• High surface to volume ratio

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pit in cell wall
one vessel member
sieve plate
cytoplasm absent (cells dead at maturity
sieve-tube member
companion cell (living)
TRACHEIDS
Fig. 29.8, p. 502
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Different Types of Leaves
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The Fine Structure of Leaves

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

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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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Structure of Roots

• Epidermis
• Cortex
• Vascular cyclinder
• Endodermis
• Pericycle
• Phloem
• Xylem
• Pith

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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
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In Conclusion

• Seed-bearing vascular plants include gymnosperms
  and angiosperms
• Plant growth originates at meristems
• Primary growth occurs in apical meristems in
  roots and shoot tips
• Secondary growth occurs at lateral meristems
  increasing diameter

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In Conclusion

• Parenchyma, sclerenchyma, and collenchyma are
  simple tissues
• Complex tissues include vascular tissues, and
  dermal tissues
• Vascular tissues distribute water and substances
  throughout the plant body
• Epidermis covers and protects the outer surfaces
  of primary plant parts

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In Conclusion

• Stems support upright growth and conduct
  substances throughout the plant body
• Leaves contain veins and mesophyll between the
  upper and lower epidermis
• Special structures, stomata, allow water and
  gases to cross the epidermis

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In Conclusion

• Roots absorb water and ions for distribution to
  plant parts
• Roots store food and support the shoot
• Wood (secondary xylem) is classified by location
  and function
• developed by M. Roig