leaf

• Mesophytic leaf


  A "standard" leaf, not specially adapted to either wet or dry environments
• Mesophytic leaf


  • Outer layer of cells on both upper and lower surface is the epidermis
  • Pores in epidermis are called stomata and allow CO2 to enter and O2, H2O to exit
  • Guard cells regulate opening and closing of stomata
• Stomata function


  1. Inflating and opening when high water content in leaf

  2. Collapsing and closing when low water content in leaf
• Palisade mesophyll


  Layer of elongated cells full of chloroplasts, specialized for capturing incoming sunlight
• Spongy mesophyll


  Full of air pockets that allow CO2 to move into leaf and O2 to diffuse out
• Vascular tissue in leaf

  • Xylem on top transporting water and minerals from roots
  • Phloem on bottom transporting sugars made in leaf to other regions
• Hydrophytic leaf


  Leaf of a plant adapted to growing in water
• Hydrophytic leaf


  • Thin epidermal layer
  • No stomata in lower epidermis
  • Large air pockets (aerenchyma) in spongy mesophyll
  • Branched sclerenchyma cells for structural support and herbivory prevention
• Xerophytic plant


  Plant adapted to dry conditions
• Pine needle


  • Epidermis more than one cell layer thick (hypodermis)
  • Cuticle coating on epidermis
  • Sunken stomata within hypodermis
  • Two vascular bundles surrounded by transfusion tissue and endodermis
  • Rounded shape to decrease surface area
• Oleander leaf


  • Stomata located in recessed pockets (stomatal crypts) lined with trichomes on lower epidermis
  • Upper epidermis has thick cuticle and no stomata
• Corn (Zea mays) leaf

  • Bulliform cells in upper epidermis that swell with water to expand leaf, and shrink to curl leaf inward