Botany 1404: Roots

  1. Order of Cell Differentiation
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  2. 4 Functions of the Root
    • Anchorage
    • Absorption
    • Storage
    • Conduction
  3. Types of Root System
    Taproot system: Primary and lateral roots, found in eudicots, magnoliids, gymnosperms

    Fibrous Root Systems: lateral roots only, found in monocots
  4. Longitudinal Regions of Roots
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    • Area of Cell Maturation: differentiation of cells, root hairs form.
    • Area of Elongation: increases root length
    • Area of Cell Division: has apical meristem, actively dividing cells.
  5. Root Cap
    • composed of parenchyma cells
    • 3 functions: protect the apical meristem, aid in penetration of soil, and control the root's response to gravity.
    • produces mucigel (slimy coating; helps with penetration)
  6. Monocots vs Eudicots (in roots)
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  7. Epidermis
    • root hairs (tubular extensions of epidermal cells) increase surface area
    • may contain thin cuticle
  8. Cortex
    • composed of parenchyma cells
    • amyloplasts: store starch, lack chlorophyll
    • large amount of intercellular space
    • contains endodermis and exodermis
  9. Exodermis (found in cortex)
    • the first cell layer in the epidermis
    • prevents water loss
    • a primary function is storage
  10. Endodermis (found in cortex)
    • the endodermis is a sheath around the vascular region
    • compact cells
    • contains casparian strips, or hydrophobic bands of suberin in the cell wall which prevent the passage of water.
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  11. Symplastic Movement
    • movement through the cells
    • symplast: interconnected cytoplasm of living cells
  12. Apoplastic Movement
    • Movement through intercellular space
    • most common type of movement
    • useful in filtering
    • apoplast: the interconnected cell-wall spaces
  13. Exodermis (found in cortex)
    • outermnost layer of cortex cells
    • contains casparian strips (see endodermis card for details)
    • reduces water loss
  14. Vascular Cylinder
    • contains vascular tissue and pericycle
    • also known as the vascular stele
  15. Pericycle
    • comprised of parenchyma cells
    • non-vascular, but originates from procambium
    • functions: it is the site of lateral root formation, and it contributes to cork cambium and vascular cambium.
  16. Secondary Growth in Roots
    • secondary growth increases width
    • two lateral meristems: vascular cambium and cork cambium
    • vascular cambium --> secondary xylem and phloem
    • Periderm originates freom pericycle
  17. Components of Periderm
    • cork cambium
    • cork
    • cork parenchyma cells
  18. Cork Cambium
    • lateral meristem
    • produces cork
    • phelloderm to inside
  19. Cork
    • dead at maturity
    • outer protective layer
    • cells containing suberin, wax, and ligin
  20. Cork Parenchyma Cells
    • inner layers of periderm
    • alive at maturity
  21. Lateral Root Growth
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    • Forms from pericycle
    • later joins with vascular cylinders of primary and lateral roots
  22. Food Storage Roots
    • stored as a starch or sugar
    • predominantly taproots
    • some fibrous roots
    • ex: carrots, beets
  23. Prop Roots
    • above ground roots
    • provides additional support
    • produced from stem
    • ex: mangroves
  24. Buttress Roots
    • roots of tropical trees are often shallow
    • provides support
  25. Air Roots (Pneumatophores)
    • roots grow to the surface of water for oxygen
    • ex: cypress trees
  26. Contractile Roots
    • often in bulbs and corms
    • Function: contracts and pulls plant further into soil
  27. Mycorrhizae
    • most plants have it, to some extent
    • fungi get sugar from plant, plant gets minerals
  28. Nodule
    a small swelling on the root of a leguminous plants in which beneficial nitrogen-fixing bacteria (Rhizobium) live.
Card Set
Botany 1404: Roots
root structure and development, tissues within the root