Plant Science:

1
Plant Science

• Botany

2
Plant Importance

• Primary food source
• Produce oxygen
• Cooling
• Renew air
• Slow wind
• Prevent erosion
• Provide shelter
• Beautify
• Building materials and fuels

3
Parts of Plants

• Four basic parts leaves, stems, roots, and
  flowers
• Flowers later become fruits or seeds
• Leaves
• Food factory location (photosynthesis)
• Shape and size vary
• Used for identification of plants
• Arrangement varies

4
Leaf Arrangement
5
External Leaf Structure

• Petiole leaf stalk
• Blade larger, usually flat part of leaf
• Veins form structural framework
• Midrib large, central vein that all other veins
  extend from
• Margins edges of leaves

6
External Leaf

• Leaf Structures

7
Internal Leaf Structure

• Cuticle waxy covering layer
• Epidermis
• skin of leaves
• Single layer of cells
• Prevent moisture loss
• Guard cells
• Open and close pores on the underside of the leaf
• Stoma
• Pores
• Allow transpiration (exchange oxygen and carbon
  dioxide)

8
Leaf Structures

• Internal Leaf

9
Internal Leaf Structure

• Chloroplasts
• Green due to chlorophyll (pigment)
• Manufacture food through photosynthesis
• A process where carbon dioxide and water in the
  presence of light are converted into sugar and
  oxygen
• 6CO2 6H2O light energy ? C6H12O6 6O2

10
Respiration

• Consume oxygen and give off carbon dioxide
• All plants need oxygen to all parts (including
  roots!)
• If not, can lead to death
• Poor drainage, over watering
• Plants produce more oxygen than they consume

11
Stems

• Functions
• Movement of materials
• Water and minerals up from roots
• Food down to roots
• Support of the leaves and reproductive structures
• Flowers, fruits, seeds
• Food storage and/or production
• If green, can use photosynthesis
• Reproduction
• Cuttings and rafting

12
Stems external structure

• Lenticels breathing pores
• Bud scale scars where a terminal bud has been
  located
• Distance between 2 scars one year of growth
• Leaf scars where leaves were attached
• Terminal bud a bud at the end of the stem
• Produces new growth

13
Stem Structure
14
Stems internal structure

• Xylem carries water and minerals UP
• Phloem carries manufactured food DOWN
• Dicots
• Plants that have 2 seed leaves (cotyledons)
• Xylem and phloem from 2 layers separated by
  cambium
• Produces all new cells (phloem to outside, xylem
  to inside)
• ie trees
• Continues to grow as long as it lives, not
  limited in size
• Monocots
• 1 seed leaf
• ie corn
• Vascular bundles phloem and xylem tissue in a
  bundle
• All cells are formed in initial growth, cells
  simply expand over time
• Limited in size

15
Monocot Stem
16
Dicot Stem
17
Monocot versus Dicot
18
Roots

• Underground, not visible (usually)
• Functions
• Anchor
• Absorb water and minerals
• Store food
• Reproduce (some plants)

19
Root Internal Structure

• Outer phloem (corklike bark)
• Cambium
• Xylem
• Very similar to stem internal structure

20
Root External Structure

• Root cap
• Produces a continuous supply of new cells
• Helps to push a path through soil
• Primary root
• Lateral roots
• Root hairs
• Absorb water and minerals

21
Root Structures
22
Root Systems Fibrous Roots

• Much easier to transplant
• Roots are shorter, smaller and more compact

23
Root Systems Tap Roots

• Longer with fewer roots

24
Root Systems Comparison
25
Flowers types

• Vary in size, shape, and color
• Complete flower has both male and female parts
• Self-fruitful
• Can pollinate itself
• Incomplete flower has only male OR female parts
  

26
Complete Flower Parts

• Sepal green, leaf-like part that covers and
  protects the flower bud before it opens
• Petals modified leaves used to attract
  pollinators
• Pollinators insects, birds, animals, wind, etc
• Used to fertilize plants to produce seeds

27
Complete Flower Parts

• Stamens male reproductive organs
• Stalk- filament
• Anther- sac-like structure at top of filament
• Pollen- male sex cells, contained in anther
• Pistil female reproductive organs
• Center of flower
• Produces eggs- when fertilized by pollen, become
  seeds
• Stigma sticky top region, used to catch pollen
• Style tube leading from stigma to ovary to
  transport pollen
• Ovary where the egg cells develop and are
  fertilized
• After fertilization, ovary becomes a fruit or
  seed coat

28
Complete Flower
29
Incomplete Flowers Differences

• Does not have both male and female parts
• Male sepals, petals, and stamen
• Female sepals, petals, and pistil
• Pollinated by same factors, but must move between
  flowers, not within flower

30
Incomplete Flower
31
The Role of Flowers

• Beauty
• Reproduction
• Economic value
• Multimillion dollar business