CHAPTER 35 PLANT FORM WOOOOO!!!!!!!

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CHAPTER 35 PLANT FORMWOOOOO!!!!!!!

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Meristems They elaborate the plant body after
germination

• - act as stem cells for plants- rapidly divide
  into differentiated cells that make up the plant
  body
• - two types
•     - apical meristems elongate the root and
  stem of plant
•     - lateral meristems produce and increase in
  girth
•         - only present in vascular plants (shrubs
  and trees)

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Apical Meristems

•  - located at the tips of stems and roots
• -  after germination, meristems produce primary
  tissues which becomes the primary plant body
  (soft shoots and roots) 
• - develop into three types of embryonic tissue
  systems
•     - protoderm- forms the epidermis
•     - procambium- produces primary vascular
  tissue
•     - ground meristem- differentiates further
  into ground tissue
• (Think of the plant as if its still an embryo,
  these are the developmental stages of plant life)

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Lateral Meristems

• - lateral meristems produce what is called
  secondary growth most of the trunk, branches,
  and older roots of trees
• - has the most dramatic effect in woody plants
  which have two lateral meristems
•     - cork cambium- produces the cork cells of
  the outer bark
•     - vascular cambium- produces secondary
  vascular tissue and lies between the xylem (wood)
  and phleom (cells close to woods surface) 
• - interesting fact removing the bark of a tree
  damages the phloem and may eventually kill the
  tree

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Organization of the Plant Body

• -- coordination of primary and secondary growth
  produces an adult plant
• - plants do not have a fixed size and vary
  between plants, even of the same species
• - number, size, structure, and location of leaves
  is dependent on plant environment
• - vascular plants have a root system ( grounds
  them and provides the plant with ions) and a
  shoot system (the stem, leaves, flowers, and
  fruit)
• - nodes and internodes on the shoot develop
  axillary buds that create new growth
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Types of Plant Tissue Dermal Tissue

• -Epidermal cells cover all the primary plant body
• - a number of specialized cells occur at the
  epidermis
• - guard cells flank the stomta (epidermal
  openings) 
•     - contain chloroplast
•     - stomata only occur on the epidermal tissue
  of leaves
•     - exchange of CO2 and O2 occur at stomata
• - Trichomes- hair like outgrowths of the
  epidermis (the "fuzzy stuff" on stems and leaves)
•     - keep leaf surfaces cool and reduce
  transpiration 
•     - some secrete sticky or toxic substances
• - Root hairs- occur at the tips of young roots
•     - keep the root in close contact with soil
  and increase absorption efficiency 
• - in vascular plants, the cork cambium produces
  bark which replaces the epidermis

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Types of Tissue Ground Cells

• - Parenchyma cells most common type of cell,
  less specialized, mainly store food and water in
  large vacuoles
• - Collenchyma cells relatively flexible, provide
  support for plant organs so they can bend without
  breaking (the strings of celery)
• - Scelrenchyma cells two types
•     - fibers long slender cells grouped in
  strands
•     - sclereids form in branched bundles
• - cell wall of scelrenchyma cells contain ligin-
  branched polymer that causes the cell wall to
  become rigid

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Types of Tissue Vascular

• - xylem cells principle water conducting tissue
  of plants
• - a combination of dead hollow cells that make
  vessels and trachieds
• - water and other ions travel from the roots
  through the xylem to the leaves and diffuses as
  water vapor out of the stomata
• - Phloem cells principal food conduction tissue
  of plants
• - carried out by sieve cells and sieve-tube
  members
• - sieve-tube memebers form sieve tubes and each
  cell is pared with a parenchyma cell (called
  compaion cells)
• -connected by plasmodesmata- which supplies the
  plant cells with organic materialsr

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Root Structure

• -there are three types vegetative organs in
  plants
•        - roots, stems, and leaves
• -there are four parts recognized in developing
  roots
•         -root cap, zone of cell division, the
  zone of elongation,        
•                and zone of maturation   
• -apical initials divide the cells that divide and
  end up on the tip become root cap cells
• -the other cells divide in opposite directions
  and pass through the three zones then they are
  fully differentiated
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The Root Cap

• -the root cap consist of two types of cells
  columella cells (the inner cells) and root cap
  cells (the outer cells)
• -the root cap cells are continuously replenished
  by the root apical meristem
• -there are golgi bodies in the root cap cells
  that secretes a slimy substance, this helps the
  root through the soil. It also helps with the
  growth of nitrogen-fixing bacteria
• -the root cap also functions as the perception of
  gravity
• -the inner (columella) cells are very specialized
      
•          -they have endoplasmic reticulum in the
  nucleus and the periphery which is located in
  the middle or top of the cell
•          -contain no large vacuoles
•          -contain amyloplasts which form on the
  sides of the cells towards the pull of
  gravitiy        
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The Zone of Cell Division

• -apical meristem is located in the center of the
  root tip , it is shaped like a inverted concave
  dome
• -cells divide every 12 to 36 hours at the edge of
  the dome
• -these new daughter cells go to one of the three
  tissues protoderm, procambium, or ground
  meristem
• -in this section genes have been identified
• -the inner cell layer regulates the flow of
  water, the outer cell layer acts as storage
• -if a mistake occurs and a cell is not in the
  correct place the cell will develop according to
  the new postition

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The Zone of Elongation

• -the cells from the primary meristem become
  several times longer than they are wide, this
  causes the root to lengthen
• -the vacuoles inside these cells increasing until
  they occupy 90 of each cell
• -cells do not grow anymore in size above the zone
  of elongation

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The Zone of Maturation

• -the cells that elongated in the zone of
  elongation are differentiated into specific cell
  types
• -many epidermal cells develop roots hairs,
  increasing surface area to absorb nutrients and
  water
• -the ground meristem produces parenchyma cells,
  they are found in the interior of the epidermis
•         -this layer called the cortex can by many
  cell layers thick and it functions in storage
• -the endodermis has walls filled with suberin,
  suberin is produced in bands called Casparian
  strips
• -the stele is everything inside of the endodermis
• -the primary xylem conducts water

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Modified Roots

• -most plants either produce tap roots or fibrous
  roots, however there are plants with roots
  specific to the function needed for that plant
• -a root that comes from something other than a
  root is called a adventitious root
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Stem Structure External Form

• -the shoot apical meristem produces stem tissue
  that creates bulges (primordia) these bulges will
  form into leaves, shoots, and flowers
• -a node is the area where the leaf is attached
• -the area between two nodes is called an
  internode
• -the bud that is a product of the primary shoot
  apical meristem is called the axillary bud
• -a leaf scar is from the leaves falling off the
  trees in the fall, a bundle scar is where the
  vascular connections were

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Internal Form

• -from the apical meristem  three primary
  meristems develop the protoderm,the ground
  meristem, and the procambium 
• -cells of the vascular cambium divide indefinitely
   and create a secondary tissue

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Leaf External Structure

• - two morphological groups- 
• microphyll- one gapless vein, and
• megaphylls- several veins
• - leaves have evolved to have a 
• flattened blade and slender stalk
• - mutant leaves have been found
• to never flatten

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Leaf Blades

•  - simple leaves undivided
• - compound leaves divided into leaflets
•     - pinnate lined leaflets
•     - palmate radial leaflets
• - alternate leaves have 
• one bud per leaf
• - compound leaves have two leaves per bud

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Leaf Internal Structure

• - entire surface covered with transparent
  epidermis and cuticle, lower epidermis contains
  stomata and guard cells
• - two layers of tissue ( the palisade and spongy
  mesophyll) rest between the upper and lower
  epidermis 
• - veins, stomata, and intercellular spaces
  function together for gas exchange

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THANK YOU!

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