Botany for the Gardener - Master Gardeners

Master Gardeners

    Botany for the Gardener

Developed by Steve Dubik
sdubik@umd.edu
Steve.dubik@montgomerycollege.edu
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Plant cell

Basic building
block of life.

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Plant cell - key points

  Cell membrane
  Cytoplasm & vacuole
  Turgor pressure
  Plasmolysis = “Wilting”
  Permanent wilting point

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Cell walls - Cellulose & lignin

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Carbon dioxide + Water + Light Energy 
Simple Sugar + Oxygen

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Electromagnetic Spectrum

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Blue light

                               Red light

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   Light Absorption of a Green Leaf

Pigments other than Chlorophyll

Anthocyanins
(reds & purples)
Carotenoids
(yellows & oranges)

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Photosynthesis
6CO2 + 6H2O + Light Energy  C6H12O6 + 6O2
  Produces food
  Energy is stored
  Occurs in cells that contain chloroplasts
  Oxygen is released
  Water and carbon dioxide is used
  Occurs under light energy

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Respiration
C6H12O6 + 6O2  6CO2 + 6H2O + Heat

 Uses food for plant energy
 Energy is released
 Occurs in all living cells
 Oxygen and food is used
 Carbon dioxide is produced
 Occurs in the dark as well as light
      Both processes are temperature dependent

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Benefits of moderate stress

 Moderately stressed trees are often most resistant to pests.
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Benefits of moderate stress

 Moderate nutrient and moisture stress does
  not impact photosynthesis but does limit
  growth, making carbohydrates available to
  support other processes such as defense
  chemicals.

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Cross-section of a Leaf
      Cuticle
      Cutin     

                      Low CO2

                      High CO2
Transpiration
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Water transport

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Vascular System
 Xylem and Phloem

 Key Distinctions

 Xylem translocates
 water and minerals
 upwards

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Vascular System
Xylem and Phloem

 Key Distinctions

 Phloem  translocates
 food materials
 primarily downward

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Cross Section of a Herbaceous Stem

                Epidermis        Cortex

                              Pith

             Primary phloem          Primary xylem
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Vascular Bundles

             Phloem tissue

            Xylem tissue

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Cross-section of a Woody Branch

Sapwood →

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Cross-section of a Woody Branch

   Springwood 

Summerwood 

               Annual Growth Rings   20

Structure of a Woody Stem

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Growth in a Woody Stem through
Successive Seasons

  Blue - xylem tissue
  Gold - vascular cambium
  Pink - phloem tissue
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Root systems

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Quick Facts
 Most tree roots are located in the top 6 to 24
  inches of the soil.
 Most tree roots occupy an area two to four
  times the diameter of the tree crown.
 Roots grow beyond the drip line.
 Few roots grow deep in the soil – they do not
  mirror the crown. Few roots grow deeper
  than 3 to 7 feet.
 Roots obtain water, oxygen and minerals
  from soil. They do not grow toward anything
  or in any particular direction. - they grow
  where the water is.                              26

Root Distribution

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Chlorosis

            Chlorosis – yellowing caused by
            loss of or reduced development of
            chlorophyll
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Necrosis
                    The death of cells,
                          resulting either
                          injury or normal
                          senescence
                             Senescence – the
                              aging process

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Necrosis

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Patterns
                         Chlorosis or
                          necrosis may take
                          on patterns i.e.,
                          marginal, veinal,
                          interveinal or entire
                         Do you see
                          symptoms on old
                          growth or new or
                          both?
            Iron deficiency on Rhododendron -
            Interveinal chlorosis
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Patterns

                       Chlorosis or necrosis
                        may take on patterns
                        i.e., marginal, veinal,
                        interveinal or entire
                       Do you see
                        symptoms on old
                        growth or new or
                        both?Inter-veinal chlorosis,
                               caused by iron
                               deficiency, starts at the
  1/24/2021   Plant Cells      top and progresses35
                               downward

Patterns
 Chlorosis or necrosis may take on patterns i.e.,
  marginal, veinal, interveinal or entire
 Do you see symptoms on old growth or new or
  both?

  Inter-veinal chlorosis
 on Rhododendron
 1/24/2021               Magnesium
                                 Plant Cellsdeficiency on primula -   36

                         Inter-veinal chlorosis on new growth

Patterns

                     Chlorosis or necrosis
                      may take on patterns
                      i.e., marginal, veinal,
                      interveinal or entire
                     What patterns do you
                      see?

              Atrazine injury on sweetgum

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Parts of twig

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  Stem of a woody dicotyledon: Prunus sp.

Bud Scales

Bud scales on Oak
(Quercus sp.)

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Leaf Scars

 Vascular Bundle Scars

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Stem Structure
Review
  Vascular bundle trace =
   Vascular bundle scar
  Lateral bud = Axillary bud
  Terminal bud scale scar

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Quick Facts
 Almost half the sugars in the leaves are used
  and lost through root growth.
 Root can grow any time of the year.
 One of the biggest killers of urban trees is soil
  compaction. Soil compaction restricts water
  and oxygen uptake by roots, and is
  associated with roads, parking lots, foot
  traffic, construction machinery, poor soil
  preparation, and a host of other factors.
 Overwatering causes the soil pore (air)
  spaces to fill with water and restrict oxygen
  uptake.
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Monocots & Dicots (Eudicots)

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Questions
Developed by Steve Dubik
sdubik@umd.edu / 301-590-2838
steve.dubik@montgomerycollege.edu
240-567-7803
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