ch 35-36

• A vascular plant consists of a shoot system and a root system
• Shoot system

  • Contains supporting stems, photosynthetic leaves, and reproductive flowers
  • Contains repetitive units consisting of internode, node, leaf, and axillary bud

  
• Root system

  • Anchors the plant
  • Used to absorb water and ions
• Protoplast

  Entire cell excluding the cell wall
• Plant cell types

  • Differ in size of vacuoles
  • Differ in thickness of secretions found in their cellulose cell walls
  • May or may not be living at maturity

  
• Cellulose fibers are parallel to microtubules

  
• Basic tissue types

  • Dermal
  • Ground
  • Vascular
• Tissue systems

  Extend through the root and shoot systems

  
• Meristems

  • Clumps of small cells with dense cytoplasm and large nuclei
  • Act as stem cells do in animals
  • One cell divides producing a differentiating cell and another that remains meristematic

  
• Apical meristems

  • Produce an extension (in length) of shoot and root
  • Composed of delicate cells that need protection

  
• Leaf primordia and root cap

  • Shelter and protect shoot and root apical meristems respectively
• Primary meristems

  • Protoderm
  • Procambium
  • Ground meristem
• Intercalary meristems

  Arise in stem internode and add to internode length
• Lateral meristems

  • Found in plants that exhibit secondary growth
  • Give rise to secondary tissues

  
• Cork cambium and vascular cambium

  Produce secondary tissues in woody plants
• Apical meristems produce the primary plant body, while lateral meristems produce an increase in the girth of a plant (secondary growth)

  
• Main plant tissue types

  • Dermal
  • Ground
  • Vascular
• Dermal tissue

  • Forms the epidermis
  • One cell layer thick in most plants
  • Covered with a waxy cutin layer constituting the cuticle
  • Contains guard cells, trichomes, and root hairs

  
• Guard cells

  Paired sausage-shaped cells that flank a stoma (opening)
• Trichomes

  • Cellular or multicellular hairlike outgrowths of the epidermis
  • Reduce evaporation, protect from light/UV, buffer temperature
• Root hairs

  Tubular extensions of individual epidermal cells that greatly increase the root's surface area and absorption efficiency

  
• Ground tissue cell types

  • Parenchyma
  • Collenchyma
  • Sclerenchyma
• Parenchyma

  • Most common type of plant cell
  • Living protoplasts that may live many years
  • Function in storage, photosynthesis, and secretion

  
• Collenchyma

  • Provide flexible support for plant organs
  • Have thickened primary walls but lack secondary cell walls

  
• Sclerenchyma

  • Have tough thick walls
  • Usually lack living protoplasts at maturity
  • Secondary cell walls often contain lignin
  • Include fibers and sclereids
• Vascular tissues


  • Xylem
  • Phloem
• Xylem


  Conducts water and dissolved minerals throughout plant
• Phloem


  Conducts a solution of carbohydrates, hormones, amino acids, and other substances necessary for plant growth
• Xylem cells


  • Vessels: Continuous tubes of dead cylindrical cells
  • Tracheids: Dead cells that taper and overlap

  
• Phloem cells


  • Sieve cells/sieve tube member cells: Living cells containing no nuclei but clusters of pores
  • Associated with companion cells
• Monocotyledons and Dicotyledons are the two groups of flowering vascular plants (angiosperms)
• Cotyledon


  The embryonic leaf in seed-bearing plants, one or more of which are the first to appear from a germinating seed
• Regions of the root


  • Root cap
  • Zone of cell division
  • Zone of elongation
  • Zone of maturation
• Root cap


  • Contains columella cells and root cap cells
  • Functions in protection of delicate tissues and perception of gravity
• Zone of cell division

  • Derived from rapid divisions of the root apical meristem
  • Contains mostly cuboidal cells with small vacuoles and large central nuclei

  
• Zone of elongation


  • Roots lengthen because cells become several times longer than wide
  • Width also increases slightly
• Root Cap


  Contains two types of cells that are formed continuously by the root apical meristem: Columella cells (inner) and Root cap cells (outer and lateral)

  
• Root Cap


  • Functions mainly in protection of the delicate tissues behind it
  • Also in the perception of gravity
• Zone of Cell Division

  • Derived from rapid divisions of the root apical meristem
  • Contains mostly cuboidal cells, with small vacuoles and large central nuclei

  
• Zone of Cell Division

  Daughter cells of apical meristem soon subdivide into the 3 primary tissues: Protoderm, procambium, and ground meristem