1. Plant Evolution & Diversity – Ch. 22-25
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Plant Evolution & Diversity – Ch

2. Kingdom Protista: Algae & Protozoa
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Kingdom Protista: Algae & Protozoa
Organisms in this Kingdom don’t fit clearly into what we call plant, animal, or fungi.
Most diverse eukaryotic Kingdom (>60,000 species).
We are interested in this Kingdom because of the Chlorophytes & Charophyceans - green algae.

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The line between Kingdom Protista and Kingdom Plantae is still being discussed……
Fig 29.4

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Origin of Plants

5. Characteristics of Green Algae - Chlorophytes
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Characteristics of Green Algae - Chlorophytes
There are unicellular and multicellular forms
Can live symbiotically with fungi as lichens

6. Fig 28.30 Volvox - freshwater Ulva – sea lettuce Caulerpa - intertidal
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Fig 28.30
Volvox - freshwater
Ulva – sea lettuce
Caulerpa - intertidal

7. Characteristics of Green Algae - Charophyceans
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Characteristics of Green Algae - Charophyceans
fresh water ponds
They are considered to be the closest ancestors of true plants. Evidence: .
Both form a cell plate during cell division
Genetic evidence – charophyceans share a greater % of similar DNA with true plants than any other algae

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Plants
So how are they different from Charophyceans??

10. What challenges did plants face when they “moved” onto land?
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What challenges did plants face when they “moved” onto land?

11. Adaptation to life on Land:
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Adaptation to life on Land: .
Multicellular gametangia
Multicellular, dependent embryos

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1. Apical Meristems –

13. 2. Alternation of Generations
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2. Alternation of Generations

14. 2 multicellular life stages: Sporophyte: Diploid
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2 multicellular life stages:
Sporophyte:
Diploid
Divides by meiosis to form spores
Spores – haploid cells that can grow into a new, multicellular, haploid organism (the gametophyte) without fusing to another cell.
Gametophyte:
Haploid
Divides by mitosis to form the gametes (egg and sperm)
Egg & sperm fuse to form the diploid zygote, which divides by mitosis to form the sporophyte

15. 3. Walled spores produced in sporangia
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3. Walled spores produced in sporangia
Sporopollenin protects the spore from harsh environmental conditions
Sporangia =
Sporocytes = the diploid cells within the sporangia that divide by meiosis to form the haploid spores

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sporocytes

17. 4. Multicellular gametangia
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4. Multicellular gametangia
Gametangia =
2 types of gametangia:
Archegonia –
Antheridia –
Sperm travel to the egg, fertilizing it within the archegonia.

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19. 5. Multicelluar, dependent embryos
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5. Multicelluar, dependent embryos
Zygote divides by mitosis to become the sporophyte.

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Other examples of adaptations to life on land: (not all plants have the following):
Cuticle –
Secondary compounds –
Roots –
Shoots - stems and leaves to make food.
Stomata – openings in the leaf surface to allow gas exchange for photosynthesis and to regulate water loss.

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More Adaptations
4. .
5. A vascular system that transports food & water from roots to shoots and vice versa.

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Fig 29.7

24. Nonvascular Land Plants: Bryophytes
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Nonvascular Land Plants: Bryophytes
Earliest land plants
3 Phyla:
Hepatophyta –
Anthocerophyta –
Bryophyta - .
Peat moss (sphagnum): doesn’t decay rapidly, stores 400 bil tons of carbon
Gametophyte is the dominant generation:

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Moss life cycle
Fig 29.8

26. Phylum Hepatophyta – liverworts
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Phylum Hepatophyta – liverworts

27. Phylum Anthocerophyta – hornworts
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Phylum Anthocerophyta – hornworts

28. Phylum bryophyta - mosses
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Phylum bryophyta - mosses

29. Peat bogs – sphagnum moss
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Peat bogs – sphagnum moss
Fig 29.10

30. Vascular Plants Vascular tissue: Xylem = water & mineral transport
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Vascular Plants
Vascular tissue:
Xylem = water & mineral transport
Phloem = food (carbohydrates) transport .
Sporophytes branched, independent of gametophyte parent

31. Seedless Vascular Land Plants
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Seedless Vascular Land Plants
Egg & sperm need moist environment to fertilize (similar to bryophytes)

32. Two phyla of seedless vascular plants:
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Two phyla of seedless vascular plants:
Phylum Lycophyta (Club Mosses)
flammable spore clouds
were tree-like in the Carboniferous period

33. Phylum Lycophyta: clubmosses, spikemosses, quillwarts
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Phylum Lycophyta: clubmosses, spikemosses, quillwarts

34. 2. Phylum Pterophyta Whisk ferns – Horsetails –
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2. Phylum Pterophyta
Whisk ferns –
Horsetails –
Ferns – produce clusters (sori) of sporangia on underside of leaves (fronds)

35. Phylum Pterophyta: ferns, horsetails, whisk ferns
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Phylum Pterophyta: ferns, horsetails, whisk ferns

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Fig Life cycle of a fern

37. Forests of the Carboniferous period (290-360 mil years ago):
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Forests of the Carboniferous period ( mil years ago):
Heat + pressure + time ----> coal
Pulled lots of CO2 out of atmosphere, cooling the earth & forming glaciers
Larger species died out when climate became drier

38. Terrestrial Adaptations of Seed Plants
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Terrestrial Adaptations of Seed Plants
Seeds replace spores as main means of dispersal.
Why?
Gametophytes became reduced and retained within reproductive tissue of the sporophyte
Heterospory –
Zygote develops into an embryo packaged with a food supply within a protective seed coat.
Pollen & Pollination - freed plants from the requirement of water for fertilization.

39. 1. Seeds replace spores as main means of dispersal.
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1. Seeds replace spores as main means of dispersal.
old way (ferns & mosses) =
new way: the sporophyte RETAINS its spores within the sporangia & the tiny gametophyte develops within the spore.
ovule =
after fertilization, the ovule becomes the seed
seed = sporophyte embryo + food supply (mature ovule tissues)

40. 2. Reduction of the gametophyte:
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2. Reduction of the gametophyte:
Similar to Fig 30.2

41. 3. Heterospory – separate male & female gametophytes
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3. Heterospory – separate male & female gametophytes
Old way: sporangia  spores  bisexual gametophyte (antheridia  sperm, archegonia -> eggs)
New way:
Microsporangia  microspores  male gametophyte  sperm

42. 4. Ovules and seed production
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4. Ovules and seed production
Megasporangia protected by layers of tissue called integuments.
Ovule =
After fertilization, embryo develops, ovule becomes a seed

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Fig 30.3

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5. Pollen & Pollination
Microsporangia  microspores  male gametophyte  sperm
Pollen =
Pollination =
Pollen tube brings sperm to egg within the ovule

45. Two types of seed plants: 1. Gymnosperms
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Two types of seed plants:
1. Gymnosperms
Evolved first
“naked seed” –
2. Angiosperms
Evolved from gymnosperms: Sporophylls rolled together to form ovaries.

46. Gymnosperms Four phyla: Ginkophyta – Cycadophyta – Gnetophyta –
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Gymnosperms
Four phyla:
Ginkophyta –
Cycadophyta –
Gnetophyta –
Coniferophyta –
Dominate forests of the N. hemisphere
Most are evergreen
Needle-shaped leaves to reduce water loss during drought

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Phylum Cycadophyta

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Phylum Ginkophyta

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Phylum Gnetophyta

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Phylum Coniferophyta

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Fig 30.6

52. Angiosperms One phylum: Anthophyta
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Angiosperms
One phylum: Anthophyta
Formerly only 2 classes: monocots & dicots. Now 4 clades (evolutionary lines):
Basal angiosperms
Magnoliads
Monocots
Eudicots

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55. Evolutionary success of Angiosperms due to:
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Evolutionary success of Angiosperms due to: .
Flowers – attract pollinators
Fruits – many forms for variety of dispersal mechanisms

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Fig 30.3

57. Notice the triploid stage!
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Notice the triploid stage!
Each pollen grain (male gametophyte) produces two sperm
Sperm travel down the pollen tube & into the ovule.
Double fertilization –
Ovule matures into the seed – contains sporophyte embryo & endosperm (food).
Ovary (female sporangium tissues) matures into the fruit.

58. Kingdom Fungi (A tiny bit of Ch. 21)
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Kingdom Fungi (A tiny bit of Ch. 21)

59. But Fungi: their bodies are filamentous
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But Fungi:
their bodies are filamentous
the organization of large structures such as
mushrooms and morels is completely different from plants,
they are heterotrophs (aquire nutrients by absorption)
Hence the boot!!

60. Ecological Roles of Fungi:
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Ecological Roles of Fungi:
Decomposers –

61. Ecological Roles of Fungi:
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Ecological Roles of Fungi:
2. Parasites – absorb nutrients from living hosts.

62. Ecological Roles of Fungi:
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Ecological Roles of Fungi:
Mutualists with plants –
. ex. mycorrhizae

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Lichens: symbiotic association of cyanobacteria or green algae and fungi.
Lichens are very sensitive to air pollution; used as indicators of air quality.

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65. Lifestyles of Fungi, continued
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Lifestyles of Fungi, continued
Mycorrhizae: mutualistic association of plant roots and fungi.
Fungus receives food from the root exudates.

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