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Wize University Biology Textbook > Plant Physiology

Plant Tissue Systems and Organs

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Tissue Systems




Dermal Tissue System

  • Epidermis: outer protective layer of dense cells
  • Cuticle: waxy coating on leaves and stems
  • Prevents water loss
  • Reduces disease transmission
  • Periderm: replaces epiderm in older woody plants
  • Specialized in different organs
  • Example: root epidermal cells form root hairs



Photo by Zephyris | CC BY
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Vascular Tissue System

  • Transport of water and nutrients through plant
  • Xylem: water transport
  • Phloem: nutrient transport
  • Stele: vascular tissue in the roots
  • Symplastic: transfer of fluids through the living cell
  • Apoplastic: transfer of fluids through dead cell wall



Photo by KI3580 | CC BY

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Ground Tissue System

  • Tissues that are not Dermal or Vascular
  • Represents most of the plant tissues
  • Parenchyma, collenchyma and sclerenchyma
  • Pith: ground tissue inside vascular system
  • Cortex: ground tissue outside of vascular system
  • Specialized for specific functions Example: photosynthesis in the leaves or nutrient storage in the roots

Photo by Frank Vincentz | CC BY

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Plant Organs

Roots

  • Anchors plants to the ground
  • Absorbs minerals and water
  • Epidermis lacks cuticle
  • Helps to absorb water
  • Taproot: main vertical root
  • Penetrates hard soil to access water and nutrients
  • Provides strong anchor for tall plants
  • Lateral Roots: branch off of taproot, absorb most water and nutrients
  • Root Hairs: modified epidermis increases surface area to improve absorption

Stems

  • Provides structure for leaves to attach
  • Positions leaves to maximize photosynthesis
  • Nodes: branches where leaves attach
  • Internodes: stem sections between nodes
  • Apical Bud: tip of the shoot where most growth occurs


Photo by KelvinSong | CC BY
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Leaves

  • Main site for photosynthesis
  • Highly variable depending on which function
  • Exchange gases
  • Control plant temperature
  • Defend plant from herbivores and diseases
  • Blade: flattened part of the leaf
  • Petiole: leaf stalk that attaches to the stem
  • Veins: vascular tissue of the leaf




Photo by KelvinSong | CC BY
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Practice: Cuticle

Describe the function of the cuticle on leaves and stems. What would happen if this were missing?
_____________ describes the movement of fluids through dead cells, whereas ______________ describes movements of fluids through living cells.