Plant Body

• A.  Double Fertilization
• 1.  Egg + Sperm1 = Zygote (Diploid)
• 2.  Polar Nuclei + Sperm2 = Endosperm (Usually not Diploid)
• B.  Establishment of Polarity of Plant Body
• 1. Suspensor pushes Developing Embryo into Endosperm
• 2. Root Apical Meristem forms
• 3. Shoot Apical Meristem and Cotyledons form
• C. Differentiation of Primary Tissue Regions
• 1. Protoderm -> Epidermis
• 2. Ground Meristem -> Cortex & Pith
• 3. Procambium -> Primary Vascular Tissue
• 4. Suspensor cells are absorbed
• D. Endosperm is often absorbed by Cotyledons
• E. Mature Seed enters period of dormancy

 A.  Top Three major human foods are grass seeds/fruit (Grains)
B.  Development of Agriculture instrumental to civilization
    1.  Wheat
• Near East, 9,000 years ago
• 550,993,000 Metric Tons

 
    2.  Rice
• Eastern China & Northern India, 7,000 years ago
• 478,775,000 Metric Tons
    3.  Corn
• Central Mexico, 5,500 years ago
• 261,162,000 Metric Tons
C. Comparison of Monocot and Dicot seeds
 
D. Seed Germination
    1.  Many seeds require exposure to cold before they germinate
    2.  Imbibition = uptake of water begins germination process
     3.  Tropism = growth response to environmental stimuli
        a.  Shoots exhibit negative gravitropism
        b.  Roots exhibit positive gravitropism

        c.  Shoots exhibit positive phototropism

III.  Primary Root Growth
 

A.  Root Apical Meristem
     1.  Promeristem
     2.  Root Cap
     3.  Quiescent Center
     4.  Protoderm -> Epidermis
     5.  Ground Meristem -> Cortex
     6.  Procambium
        -> Endodermis + Pericycle
            +Primary Xylem + Primary Phloem
 
B.  Zones of Cell Activity
    1.  Cell Division + Cell Elongation
        a.  Perpetuates Promeristem
        b.  Gives rise to Cells of Root Cap and Root Body
    2. Cell Elongation
        a.  Plant Cells don't migrate or slide past one another
        b.  As cells elongate the root apical meristem is pushed
            deeper into  the soil
    3.  Cell Maturation
        a.  Root Hair Formation from Epidermis
        b.  Lateral Root Formation from Pericycle
        c.  Secondary Xylem and Secondary Phloem from Vascular
                      Cambium

IV.  Primary Shoot Growth
 

A.  Shoot Apical Meristem
    1.  Lateral Organ Production
        a.  Leaves
        b.  Axillary Buds
        c.  Flower Parts
 
     2.  Tissue  Differentiation
        a.  Promeristem
        b.  Protoderm -> Epidermis
        c.  Ground Meristem -> Cortex + Pith
        d.  Procambium -> Primary Xylem + Primary Phloem
B.  Zones of Cell Activity
    1.  Cell Division + Cell Elongation
        a.  Perpetuates Promeristem
        b.  Gives rise to Cells of Stem, Leaves, Axillary Buds, Flower Parts
 
    2. Cell Elongation
        a.  Plant Cells don't migrate or slide past one another
        b.  As cells elongate the shoot apical meristem is pushed             higher into the air
    3.  Cell Maturation
        a.  Guard Cell and Trichome Formation from Epidermis
        b.  Lateral Shoot Formation from Axillary Buds often delayed
        c.  Secondary Xylem and Secondary Phloem from Vascular Cambium

V.  Leaf Development
 

A. Leaf Primordia develop into Leaves through

1.  Cell Division + Cell Expansion
2.  Cell Expansion
3.  Plant Cells don't migrate or slide pase one another so
Pattern of Cellular Processes determines shape of mature leaf
 
B.  Leaflet Primordia form on Leaf Primordium in Compound Leaves
C.  Primordia can also form flower parts
 
 
1.  Sepals
2.  Petals
3.  Stamens
4.  Pistils
D.  Tissue Differentiation

1.  Protoderm -> Epidermis
2.  Ground Meristem -> Palisade and/or Spongy Mesophyll
3.  Procambium -> Primary Xylem + Primary Phloem
 
 
E.  Leaves and Flower parts generally do not exhibit secondary growth