Plant Organs

• Epidermal cells are usually thin, flat, and tightly packed together to form a continuous sheet over the surface of the organ.
• The leaf is a plant organ that contains different tissues
• Epidermal cells


  Very thin cells that form the epidermal tissue covering the top and bottom of the leaf
• Upper epidermis


  • Transparent to allow light to pass through
  • Covered with a waxy cuticle to reduce water evaporation
• Lower epidermis


  • Contains tiny pores called stomata
  • Stomata allow carbon dioxide to enter and oxygen to leave
• Guard cells


  Found on either side of the stomata, help control water vapor passing out of the leaf
• Palisade mesophyll


  Packed full of chloroplasts that contain chlorophyll to absorb light energy for photosynthesis
• Spongy mesophyll


  Full of air spaces that allow carbon dioxide to diffuse to the palisade cells and oxygen to diffuse out
• Xylem


  Transports water and dissolved mineral ions from roots to stem and leaves
• Phloem


  Transports dissolved sugars produced by photosynthesis from leaves to rest of plant
• Translocation


  Movement of sugars through phloem tissue
• Meristem tissue


  Contains stem cells that can differentiate into different plant tissues, found in growing tips