NOT ON AP: NEEDED FOR BACKGROUND

1
NOT ON AP NEEDED FOR BACKGROUND

• Plant Structure and Growth

2
The Diversity of Angiosperms

• Angiosperms (flowering plants) can be divided
  into 2 major categories
• Monocots
• have one seed leaf (cotyledon)
• Dicots
• have 2 seed leaves (cotyledons)

3
Monocots

• Monocots have only 1 cotyledon (seed leaf)
• Examples of monocots
• Corn, wheat, lilies, orchids, palms

4
Dicots

• Dicots have 2 cotyledons (seed leaves)
• Examples of dicots
• Roses, clover, tomatoes, oaks, daisies

5
Woody vs. Herbaceous Plants

• Angiosperms can also be subdivided into the
  groups of woody and herbaceous plants
• Woody plants are made of cells with thick cell
  walls that support the cell body
• Examples trees, shrubs, vines
• Herbaceous plants do not produce wood as they
  grow, and instead have smooth stems
• Examples dandelions, sunflowers

6

• Anatomy of an
• angiosperm

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Angiosperm structure

• Three basic organs
• Roots (root system)
• fibrous mat of thin roots
• taproot one large, vertical root
• Stems (shoot system)
• nodes leave attachment
• internodes stem segments
• axillary bud dormant, vegetative potential
• terminal bud apex of young shoot
• Leaves (shoot system)
• blade
• petiole

8
Plant Organ Systems

• Dermal (epidermis) single layer of cells for
  protection
• Cuticle a waxy coating on many leaves and stems
• Vascular (material transport)
• xylem water and dissolved minerals roots to
  shoots
• phloem food from leaves to roots and fruits
• Ground (photosynthesis, storage, support)
  tissues that are neither dermal or vascular
• Pith internal to the vascular tissue
• Cortex external to the vascular tissue

9
Plant Growth

• Life Cycles
• annuals complete their life cycle in 1 year or
  less (wildflowers food crops)
• biennials complete their life cycle in 2 years
  or less (beets carrots)
• perennials live many years (trees shrubs)
• Meristems have indeterminate growth cycles
• apical tips of roots and buds primary growth
• lateral cylinders of dividing cells along length
  of roots and stems secondary growth (wood)

10
The Root System

• What do roots do?
• Anchor the plant in the soil
• Absorb minerals and water
• Store food
• Types of root systems
• Fibrous root system
• Found mostly in monocots
• Taproot system
• Found mostly in dicots

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Primary growth

• Roots
• root cap protection of meristem and pushes
  through soil
• zone of cell division primary (apical) meristem
  where new root cells are produced
• zone of elongation cells elongate pushes root
  tip into soil
• zone of maturation complete maturation and
  differentiate to become tissues

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The Shoot System

• The shoot system consists of
• vegetative shoots (which bear leaves)
• floral shoots (which bear flowers)
• Stems have 3 important functions
• Producing leaves, flowers, branches
• Holding leaves up to the sunlight
• Transporting substances between roots and leaves

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Primary Tissues of Stems

• Vascular bundles (xylem and phloem)
• Surrounded by ground tissue (xylem faces pith
  (central core of plant) and phloem faces cortex
  (tissue between the vascular tissue and the
  dermis). . . See diagram below)

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How do stems grow?

• Primary growth
• Increase in length
• Occurs by cell divisions in apical meristem (at
  top of shoot)
• Secondary growth
• Increase in width
• Occurs by cell divisions in the lateral meristems
  (also known as vascular cambium)

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Apical Meristems
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The Shoot System Leaves

• Leaves are attached to stems at nodes
• The area between 2 nodes is called an internode

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The Shoot System Leaves

• Leaves are the primary photosynthetic organs of
  most vascular plants
• Most leaves have a flattened blade and a petiole,
  which is the stalk that attaches the leaf to the
  stem

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Primary Tissues of Leaves

• Epidermis/cuticle (protection desiccation)
• Stomata (tiny pores for gas exchange and
  transpiration) surrounded by guard cells which
  open and close stomata
• Mesophyll ground tissue between upper and lower
  epidermis site where photosynthesis takes place

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Secondary Growth

• This type of growth produces thickness in stems
  and roots in woody plants
• Two lateral meristems
• vascular cambium produces secondary xylem
  (wood) and secondary phloem (diameter increase
  annual growth rings)
• cork cambium produces thick covering that
  replaces the epidermis produces cork cells cork
  plus cork cambium make up the periderm (outer,
  protective coat)
• Bark all tissues external to vascular cambium
  (phloem plus periderm)

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• The formation of
• bark

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Tissue Systems in Plants

• All 3 plant organs (root/stem/leaf) have dermal,
  vascular, and ground tissue systems
• Dermal Tissue System
• Outer protective covering, similar to our skin ?
• Protects the plant from water loss and disease
• The cuticle is a waxy coating that helps to
  prevent water loss

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Tissue Systems in Plants

• Vascular Tissue System
• Carries out long-distance transport of materials
  within the plant
• Xylem and phloem are examples of vascular
  tissues
• Ground Tissue System
• Pith (inside vascular tissue) and cortex
  (outside vascular tissue) are examples of ground
  tissue
• Includes cells specialized for storage,
  photosynthesis, and support

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Summary of primary secondary growth in a woody
a stem
PRIMARY PRIMARY LATERAL
SECONDARY MERISTEMS TISSUES
MERISTEM TISSUES
Protoderm Epidermis Secondary
phloem Primary phloem Vascular
Procambium cambium Secondary Primary
xylem xylem Ground meristem Ground Pith
tissue Cortex Cork cambium Cork
Apical meristem of stem
Periderm
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Microscope Activity

• You will be examining various slides of plants
• In your lab notebooks, I want you to draw what
  you see at the 100X and 400X powers and label as
  many parts as you can
• You may use your textbooks for aid (look at the
  diagrams in Ch. 35)
• pp. 721 - 726