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
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
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
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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
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
Mark Yourself Question
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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.