tissue introduction meristematic tissue ground tissue dermal tissue vascular tissue

Ground Tissue is simple non-meristematic tissue (non-dividing tissue) made up 3 cell types:paranenchyma, collenchyma and sclerenchyma.This tissue generally forms either the pith, cortex or bulk of leaf ( mesophyll)/

Parenchyma cells-

  • most abundant cells in plants;
  • spherical cells which flatten at point of contact;
  • alive at maturity; pliable, primary cell walls;
  • large vacuoles for storage of starch, fats, and tannins (denature proteins);
  • primary sites of the metabolic functions such as photosynthesis, respiration, and protein synthesis;
  • they are "ready reserves" from which a plant makes specialized cells to meet its changing needs

Specialized parenchyma:

Chlorenchyma- photosynthetic cells; have high density of chloroplasts

Aerenchyma- prominent intercellular spaces that improve gas exchange capacity of the tissue; provide maximum support with a minimum metabolic requirement

Transfer cells- specialized for short distance transfer of solutes between cells; have secondary cell walls; they are inner extensions of wall that increase surface area.

*transfer cells occur in areas of high solute transport, such as secretory tissues, which release substances that are produced within the protoplasm and are moved outside, i.e., nectar cells, mucilage in sundews, and resins

 

II. Collenchyma cells- colla = glue, glisten

  • living protoplasm;
  • unevenly thickened primary cell walls; elongate cells;
  • longer than wide; just beneath epidermis;
  • function to support growing organs, grass, floral parts, and border veins; their nonlignified cell walls can stretch

 

 

III. Sclerenchyma cells- ( skleos = hard)

  • most are dead at maturity;
  • rigid, thick, lignified, nonstretchable secondary cell walls.
  • there are 2 types of sclerenchyma cells:
sclereids or stone cells we saw in lab- short; variable shape; form hard layers such as the shells of nuts and seed coats; produce the gritty texture of pears

fibers- long, slender; occur in strands or bundles; tiny cavity or lumen; the different hardnesses of fibers are used to make coarse rope, linen cloth, etc.

 

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