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