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Ch 6: leaves (external structure of foliage leaves download-2 (dorsal…

- - - - bundles of vascular tissue.
      - distribute water
      - collect sugars
      - cann occur in netted pattern
        
        called reticulate venation
  - - - usually smooth
  - - - allows for flexibility
  - - - petiolule
        
        the stalk of leaflet
      - rachis
        
        extension of petiolule
      - small, and very flexible
  - - - leaving a leaf scar
        
        mark shows where leaf was
- - - - reduces surface-to-volume ratio
        
        reduces capacity for CO2 intake
      - favors water conservation
      - can be cylindrical or spherical
    - - mesophyll has few air spaces
        
        reduces internal evaporative surface are
        
        water loss through stroma
        
        makes mesophyll transparent
        
        easier light intake
  - - - if not
        
        plant would lose energy
    - - tend to have wax on leaves
    - - leaves have become perennial
        
        makes them more resistant to
        
        animals
        
        low temps
        
        ultraviolet light
        
        fungi
  - - - thick cuticle
      - epidermis cells have thick wall
      - hypodermis cell walls have thick walls
    - - can be short or long
  - - - protects it from harsh weather
      - produces waxy substance
  - - - modified leaves of axillary buds
      - protection against herbivores
    - - Mesophyll consists of packed fibers
        
        maturation causes lignin in walls
        
        makes them resistant to decay
  - - - causes tendril to curl around object
  - - - leaves lack palisade parenchyma
      - lack spongy mesophyll
      - have bundle sheaths with large chlorophyllous cells
  - - - to obtain nitrogen for amino acids and nucleotides
    - - thin, parenchymatous
      - capable of photosyntheisi
      - numerous stromata
      - has vascular bundles and mesophyll
      - the lamina is tubular
        
        allows secretion of watery digestive fluid
- - - - called transpiration
      - contains layer of cutin/wax
  - - - upper surface layer of cells
      - also called palisade mesophyll
      - main photosynthetic tissue of most plants
      - some plants have this along both surfaces
    - - spongy mesophyll
        
        permits CO2 rapid diffusion
        
        goes to all interior parts
  - - - also called mid-vein
      - involved mostly in conduction
      - contain primary Phloem and Xylem
      - provide support
      - may contain bundle sheath
        
        protects vasular tissues
    - - involved in conduction
      - contain primary Phloem and Xylem
      - provide support
      - may contain bundle sheath
        
        protects vascular tissues
    - - important for releasing H20 from xylem
      - loading sugar into Phloem
    - - have bundle sheath extension
        
        help give rigidity
        
        provide water transportation
  - - - play role in shedding of leaves
    - - 1,3,5 or more vascular bundles
    - - 2 small tissue flaps at base
      - may protect apical meristem
      - contribute to photosynthesis
- - - - initiated by shoot apical meristem cells
        
        forming a hood shape
    - - elongation is caused by mitosis
        
        stops when certain size is reached
      - sheath is formed
      - opposite side develops into leaf
      - meristem present= growth
  - - - develop from shoot apical meristems
        
        forming a hood shape
    - - develop into
        
        flat structures
        
        different shapes and sizes