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 PLANT ORGANS, TISSUE SYSTEMS, TISSUES AND CELL TYPES
3 TISSUE SYSTEMS OCCUR IN PLANTS
1) Dermal Tissue System
    Function: Protection from the environment and water loss. 
    Tissues:
    a) epidermis - single layer of cells on primary (herbaceous ) plant parts. 
    b) periderm or bark - a corky tissue that replaces epidermis on secondary (woody) plant parts.

2) Vascular Tissue System
    Function: Conduction of water, nutrients, sugars and hormones throughout the plant. 
    Tissues:
    a) xylem - conducts water and nutrients up roots, stems and leaves. 
    b) phloem - conducts water, sugar, hormones, etc. down and up roots, stems and leaves;
                       moves from where produced (called sources) to where needed (called sinks).

3) Ground or Fundamental Tissue System
    Function: Storage, support, filler tissue and site of photosynthesis. 
    Tissues:
    a) cortex - outer region of stems and roots. 
    b) pith - center of stems. 
    c) mesophyll - middle of leaves and flower petals.
 

3 BASIC CELL TYPES COMPRISE MOST OF THE TISSUES OF PLANTS
1) parenchyma
  • thin, non-lignified primary cell walls 
  • filler, storage, protection, photosynthesis 
  • examples: flesh of potato, lettuce leaf 
parenchyma
isodiametric
2) collenchyma
  • unevenly thickened, non-lignified primary cell walls 
  • support in growing tissues 
  • example: strings in celery stalks 
collenchyma
longer than wide
3) sclerenchyma
    2 Types

    a) fiber

    b) sclereid or
         stone cell

  • evenly thickened, lignified (tough) secondary cell walls
  • dead at maturity 
  • support in mature tissue 
  • examples: 

  • fiber - bamboo cane 
    sclereid - seed coat 
    stone cell - pear fruit 
fiber
long, slender, pointed on both ends
sclereid or stone cell 
multi-shaped, or columnar