1. Chapter 22: Plant Diversity

2. Intro to Plants What is a Plant? Basics Multicellular Eukaryotic
Autotrophic
Cells have cell walls made of cellulose

3. Autotrophic
Photosynthesis – produces organic compounds (a.k.a. food) using sunlight and CO2
Requires Chloroplasts – organelles where photosynthesis takes place

4. Establishment of Plants on Land
Nonvascular Plants – 1st evolved from a multicellular green algae
Lack vascular tissue for transporting water & nutrients
Grow close to the soil to get moisture

5. Vascular Plants – later evolved from a group of nonvascular plants
Have vascular tissue for transporting water & nutrients from roots to leaves and organic material back down to the roots.
1st vascular plant was named Cooksonia

6. Vascular Tissue
Xylem
Composed of thick-walled cells that conduct water/minerals from roots through stems to the leaves.
At maturity, xylem cells are dead, leaving only cell walls.

7. Phloem
Composed of cells that conduct sugars &nutrients throughout plant’s body.
Cells are alive at maturity, & contain cell walls, cell membrane, & cytoplasm. Cells lack most organelles.

8. Absorbing Nutrients Preventing Water Loss
Early plants lacked roots. Relied on fungi for nutrients from the soil.
Preventing Water Loss
Cuticle – waxy covering that covers leaves & stems to prevent water loss through evaporation
Stomata – pores in leaves that allow O2, CO2, & water to move in/out of plant
Roots obtain water from soil, replacing water lost to the atmosphere

9. Cuticle
Stomata

10. Dispersal on Land
Spores – early plants produced spores that dried out & were carried by wind
Pollen – special type of spore used by seed plants; carries sperm cell
Seeds – plant embryo packaged with a food source that can be carried by wind, water, or animals

11. Overview of Plant Evolution
1st plants lacked vascular tissue & reproduced by spores = Bryophytes (mosses)
2nd group of plants developed vascular tissue, but still reproduced by spores = Pteridiophytes (ferns)
3rd group of plants had vascular tissue and reproduced by seeds
Gymnosperms – seeds made in cones
Angiosperms – seeds made in flowers

12. Overview of Plant Evolution

13. 3 Groups of Bryophytes:
Mosses 2. Liverworts
Hornworts

14. 2 Groups of Seedless Vascular Plants (Pteridiophytes)
Club Mosses
Ferns

15. 2 Groups of Seed Plants Gymnosperms
Seeds do not develop with in a fruit
Most seeds develop inside a cone

17. Angiosperms Seeds develop within a fruit
Fruits develop from part of a flower
Angiosperms are also called flowering plants

18. Flowering Plants Kinds of Angiosperms Monocots
Seeds have 1 cotyledon – embryonic leaf
Long, narrow leaves with parallel veins
Flower parts are in multiples of 3

19. Dicots Seeds have 2 cotyledons Broader leaves with branching veins
Flower parts are in multiples of 4 or 5

20. The Flower
What is a flower?
Specialized reproductive structure

21. Flower Structures
Sepals – small leaves that protect the outside of the flower
Petals – colored leaves to attract pollinators
Stamen – male part; produces pollen
Anther – top of stamen where pollen is produced
Filament – stalk that supports of the anther

22. Plant Sepals
Anther

23. Pistil/Carpel – female part; produces ovules
Stigma – sticky tip of pistil to grab pollen
Style – stalk that supports stigma
Ovary – base of pistil where ovules develop

24. Attracting Pollinators – animals pick up pollen & carry it to another plant
Brightly colored petals – bees, birds
Sugary nectar
Strong odors - bats, moths that feed at night
Attractive shapes
**Wind can also disperse pollen.

25. Exploding Seeds

26. Plant Tissue Systems Plant Tissue Types
Dermal tissue – protective, outer layer of a plant
Vascular tissue – forms strands that conduct water, minerals, & organic compounds through plant
Ground tissue – makes up inside of nonwoody plants (roots, stems, leaves)

27. Epidermis – “skin” of nonwoody plants
Dermal Tissue
Epidermis – “skin” of nonwoody plants
Usually a single layer of cells
Can form hair-like extensions
On stems & leaves, hairs trap moisture close to surface to prevent water loss
On root tips, root hairs increase surface area for more absorption

28. Cuticle – waxy covering over epidermis
Protects plant
Prevents water loss by repelling water

29. Dermal Tissue of Woody Plants
Several layers of cells and is called cork.
Contains a waterproof chemical.
Lacks a cuticle
Protects plant, exchanges gases, & absorbs minerals

30. Stomata
Cuticle will not allow gases to pass though it, so plants need a way to bring CO2 in and let O2 out.
Stomata are pores that permit the exchange of these two gases.
Guard cells border each stomata and open/close them.
When open, plants gain CO2 but lose water.
When closed, plants conserve water, but photosynthesis slows (no CO2).

31. Stomata

32. Vascular Tissue System Xylem
Composed of thick-walled cells that conduct water/minerals from roots through stems to the leaves.
At maturity, xylem cells are dead, leaving only cell walls.

33. Phloem
Composed of cells that conduct sugars &nutrients throughout plant’s body.
Cells are alive at maturity, & contain cell walls, cell membrane, & cytoplasm. Cells lack most organelles.

34. Ground Tissue Location Found between dermal and vascular tissue.
Most abundant in nonwoody plants.
Most cells remain alive with thin cell walls and nuclei.
Cells with thicker cell walls lose their nuclei & cell contents as they mature (they die ).

35. Function depends on location in a plant
In leaves, ground cells perform photosynthesis.
In stems & roots, ground cells mainly support the plant & store water, sugar, & starch.
In angiosperms, ground tissue makes up the flesh of fruits.
Ground tissue is mainly absent in woody plants.