Plant Tissues: Dermal

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Plant Tissues: Dermal
2013-02-21 13:19:50
BIL 220

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  1. Dermal Tissues
    • Complex Tissues
    • Located on surface of plant body
    • Types:
    • Epidermis
    • Periderm
  2. Epidermis
    (thickness, covering, types)
    • Usually one layer thick on surface of leaves, stems, roots
    • Outermost layer of cells on primary plant body
    • Covered by a waxy cuticle on leaves and stems
    • Cell Types:
    • Epidermal cell proper (most prevalent)
    • Guard Cells
  3. Epidermal cell proper
    • generally parenchyma
    • shape varies (often tabular)
    • Most lack chlorophyll
    • Secrete waxy cuticle over leaves and stems of primary plant
    • Protects against evaporation and microbial invasion
    • In root- contain root hairs for water absorption
  4. Epidermis: Guard Cells
    • Paired, opening between is stomata
    • Regulates gas exchange
  5. Periderm
    (covering/ function)
    • Outer covering on secondary plant body (stems and roots)
    • Replaces epidermis in these regions
    • Functions in protection
  6. Periderm composed of?
    • cork  (outer bark); cork cells are dead at maturity and filled with suberin , a water-proofing substance
    • cork cambium (meristematic tissue)
  7. Vascular Tissues
    • Complex, conductive tissues of plant
    • Transport of water, minerals and food
    • Located throughout plant body
    • Types:
    • Xylem
    • Phloem
  8. Xylem
    (Job, tissue, cells)
    • Transport of water and dissolved minerals upward through plant body
    • Continuous pathway from roots, stems and leaves
    • Complex tissue
    • Chief cells:
    • Trachieds
    • Vessel elements
    • Other cell types:
    • Parenchyma
    • Sclerenchyma
  9. Xylem
    Chief cell: tracheids
    • Chief water conducting cells in most lower vascular plants (ferns, etc) and gymnosperms
    • Elongated cells with no protoplast or nuclei at maturity (dead)
    • Secondary cell walls contain pits (holes in sec wall
  10. Xylem
    vessel elements
    • Chief water conducting cells in higher plants
    • Elongated cells with no protoplast or nuclei at maturity
    • Secondary cell walls contain pits and perforations (hole in primary and sec wall)
  11. Phloem
    • Transport food up and down plant
    • Newly synthesized organic molecules
    • Complex tissue
    • Major cell types:
    • Sieve tube elements and companion cells
    • Sieve cells and albuminous cells
    • Other cell types:
    • sclerenchyma
  12. Phloem (sieve cells and tube elements)
    • Elongated cells, alive at maturity but lack most organelles
    • Contain sieve plates
  13. Phloem
    albuminous and companion cells
    • Specialized parenchyma cells
    • Alive at maturity
    • Necessary for loading and unloading or organic material into or out of sieve cells and tube elements