Plant Structures

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Plant Structures

• Original PowerPoint created by
• Mr. Morgan
• Modified by Georgia Agriculture Education
  Curriculum Office
• June 2002

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What Are primary parts of plants?

• Leaves
• Stems
• Roots
• Flowers

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What are the functions of leaves?

• Capture light
• Exchange gases
• Provide a site for photosynthesis
• Some leaves store food and water
• Some form new plants and provide support

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What is photosynthesis?

• It is a process by which plants combine water and
  carbon dioxide in the presence of chlorophyll and
  sunlight and produce carbohydrates and release
  oxygen.

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Why is photosynthesis important?

• Light is the most important source of energy for
  living things. Photosynthesis converts light
  into nutrients that can be used by plants and
  animals.
• Releases oxygen

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Photosynthesis

• Light6CO212H20-Sunlight-gt C6H12066O26H20

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There are two parts of photosynthesis--the light
and dark reactions.

• The light reactions produce chemical energy from
  light.
• The dark reactions convert carbon dioxide into
  carbohydrates.

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Leaves in gas exchange

• Oxygen, Carbon Dioxide, and Water exchanged from
  Stomata
• Pores open in day to transpire H2O and allow
  gases to enter
• Close during dry conditions to prevent H2O loss.

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External Parts of Leaves

• Petiole- Stalk of leaf that attaches to stem
• Midrib- Main vein of vascular tissue
• Blade- Photosynthetic site of leaf

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Stomata

• Openings on the epidermis
• allows air into leaf
• allows H2O and oxygen out of leaf

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Stems

• Water and mineral transport by capillary action
  and cohesion to the leaves.
• Transport food to the roots
• Gas exchange
• Produce and support new leaves, branches, and
  flowers

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Internal parts of stem

• Phloem
• Xylem
• Cambium
• Pith
• Cortex

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Functions

• Phoem-Sugar and carbohydrates to roots
• Xylem- Water and nutrients
• Cambium- Growing part of stem

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Function Cont

• Pith-Occupies the central area of the stem
• Cortex- Composed of several layers of
  thick-walled cells

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External parts of stem

• Buds
• Nodes
• Internodes

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Modified Stems

• Rhizomes- Horizontal underground stems(Bermuda
  Grass
• Stolons- Horizontal above ground
  stems(strawberries)
• Tubers- Greatly enlarged tip of underground stem

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Cont.

• Bulbs- budlike structure consisting of a small
  stem (onion)
• Corms- Fleshly leaves underground stems with few
  nodes(gladiolus)

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Functions of Roots

• Anchor plants in soil
• Absorb water and nutrients
• Some store reserves for future uses(Potato)
• Propagation

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Taproots

• Disadvantages
• Difficult to remove or harvest
• do not stabilize well

• Advantages
• Penetrates deeper
• Obtain water from other levels
• Anchor plant

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Fibrous

• Advantages
• Shallower, better for fertilization Water
• Stabilize in soil better

• Disadvantage
• Less drought resistant
• Tend to get exposed during cultivation

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Primary Roots

• Grow down into the soil and may branch repeatedly
  into lateral roots
• Taproot is a primary root

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Lateral Roots

• Called Secondary roots
• grow horizontally away from the primary root
• Some grow downward

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Adventitious

• Came from stems or leaves instead of another root
• Prop root of corn and grapes are examples that
  give support

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Fibrous Root

• Root structures in which the primary and lateral
  roots develop equally so there is not a definite
  taproot.

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Storage Roots

• Are structures such as those of carrots and sweet
  potatoes which are used for food storage.

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What do stems and roots have in common?

• Both have xylem and phloem cells for transport.

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Male flowers and their parts and functions.

• Stamen- has two parts- filament and
  antherFilament- supports the anther
• Anther- Produces pollen grains

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Female parts and their functions

• Ovule-develops into a seed
• Ovary- surrounds the ovule, later becomes the
  fruit
• Style-supports the stigma
• Stigma- receives the pollen grain
• Pistil- All three female parts together

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Other parts of flower

• Receptacle- enlarged part of the flower stalk
  where floral part is.
• Sepals- outer protective parts of buds
• Petals- the colored part of the flower used to
  attract insects

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Complete Flower

• Both have Male and Female parts

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Incomplete Flowers

• Have either male or female parts but not both

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Monoecious

• Plants that have male and female flower parts on
  separate plants

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Dioecious

• Have both parts on the same plant.

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Pollination

• The transfer of pollen from one anther to anther
  stigma.
• Two ways- self-pollination Cross-pollination
• Bees and Wind

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The End