1. CHARACTERISTICS OF PLANTS:
Eukaryotic Cells
Autotrophic and Multicellular
Cell Walls Contain Cellulose
Alternation of Generation
Embryonic Development

2. More than 280,000 species of plants inhabit Earth today.
Land plants (including the sea grasses) evolved from a certain green algae, called charophytes

3. Spirogyra, a model chlorophyte

4. CHALLENGES FACED BY PLANTS
FOR LIFE ON LAND
Obtaining enough water
Transporting water and dissolved
substances to other parts of the plant body and transporting the products of photosynthesis to other parts of the plant that don't conduct photosynthesis

5. Preventing excessive loss of water
by evaporation
Maintaining an extensive moist
surface for gas exchange
Supporting a large plant body against
gravity
Carrying out reproduction when there
is little water

6. Lastly, withstanding the extreme
fluctuations in temperature,
humidity, wind, and light which
are moderated in water due to
its high heat capacity

7. Land Plants Evolved from Green
Algae.
Common Characteristics:
Rose-shaped complexes for cellu-
lose synthesis
Peroxisome enzymes
Structure of flagellated sperm
Formation of a phragmoplast

8. Charophyceans: Chara (top), Coleochaete orbicularis (bottom)

9. Several Features of Land Plants Differ From Those of Green Algae
Multicellular sex organs with
an outer layer of jacket cells
Cuticles on leaves

10. Derived Traits of Land Plants
(These traits are absent in the
charophyceans – next four
slides)

11. Apical Meristems of Plant Shoots and Roots

12. Alternation of Generations: a Generalized Scheme

13. Multicelllular Gametangia: Archegonium of Marchantia (left), Antheridium of a hornwort (right)

14. Multicellular Dependent Embryos: Marchantia (left), Shepherd's purse (right)

15. Cooksonia, a Vascular Plant of the Silurian Period
Walled Spores Produced In Sporangia
Cooksonia, a Vascular Plant of the
Silurian Period

16. Leaves of Vascular Plants

17. There are four main groups of land plants:
Bryophytes
Pteridophytes
Gymnosperms
Angiosperms – 90% of all
plants

18. Representatives of the Four Major Groups of Plants

19. There are four great episodes in the evolution of land plants:
the origin of bryophytes from algal ancestors
the origin and diversification of vascular plants
the origin of seeds
the evolution of flowers

20. p. 578

21. Some Highlights of Plant Evolution
140 mya
360 mya
420 mya
475 mya

22. Reduction in the Size of the Gametophyte

23. Bryophytes
Liverwort
Liverwort
Hornwort
Moss

24. Moss with Sporophytes
Gametophytes

25. Liverwort, Marchantia
Antheridia Archegonia

26. Hornwort – a Characteristic Bryophyte

27. Moss (Polytrichum) Life Cycle

28. The life cycle of Polytrichum, a moss

29. Pteridophytes
Club
Moss
Whisk Fern
Horsetail
Fern

30. Whisk Fern, Psilotum

31. Club
Moss

32. Club Moss in Olympic National
Forest – WA State

33. Club Moss in Olympic National
Forest

34. Club mosses (Lycopodium) have microphylls, with single veins

35. Horsetail Horsetails and the other seedless vascular plants
have highly
branched
vascular
systems called
megaphylls.

36. Fern sporophyll, a leaf specialized for spore production

37. Fern Sori (clusters of sporangia)

38. modified leaves with sporangia Most seedless vascular plants
Sporophylls
modified leaves with sporangia
Most seedless vascular plants
Are homosporous, producing one type of spore that develops into a bisexual gametophyte
sporangium > single > bisexual > eggs and sperm
type of gametophyte
spore

39. All seed plants and some seedless vascular plants
Are heterosporous, having two types of spores that give rise to male and female gametophytes
megaspore > female gametophyte > eggs
microspore > male gametophyte > sperm

40. Fern Life Cycle

41. The Life Cycle of a Fern

42. The first seed plants evolved about 360 million years ago, near the end of the Devonian Period.
A seed consists of a plant embryo packaged along with a food supply within a protective coat.

43. The Reduced Gametophyte of Seed Plants are Protected in Ovules and Pollen Grains

44. From Ovule to Seed

45. The Gingko (biloba) tree is a “living fossil” and has been on
Phylum Ginkgophyta
The Gingko (biloba) tree
is a “living fossil”
and has been on
the earth virtually
unchanged for
at least 150 million years. It
produces “naked” seeds, as do all
other gymnospernms.

46. Seeds
Female Gingko

47. The Ginkgo Tree

48. Male
Female

49. Phylum Cycadophyta: Sago Palm/Cycad

50. Sago Palm or
Cycad,
a gymnosperm

51. Sago Palm or Cycad Cones
Figure 24.19

52. Phylum Gnetophyta: Welwitschia

53. Phylum Gnetophyta:
Ephedra

54. Ephedra
Figure 24.21

55. Phylum
Coniferophyta:
Douglas
Fir

56. These are
male cones
on a pine
tree.

57. Female Pine Cone
Male Pine
Cones

58. This picture was taken in Sequoia National Park in Central California.
One sequoia tree, nicknamed the “General
Sherman Tree” is the heaviest/largest tree in the world. It is over 2300 years old and weighs
over 1300 tons.

59. This picture is of
“The Lone Cypress”
taken on the 17
mile drive on the
Monterey Peninsula.
It is one of the most commonly photographed trees in the
world.

60. This picture is of the Bristlecone Pine Tree which is the oldest tree in
the world – over
4700 years old.
“Methusaleh” as the oldest tree is called is located in the White Mountains of California.

61. Pine Life Cycle

62. The Life Cycle of a Pine

63. The great majority (90%) of modern-day plant species are flowering plants, or angiosperms.
Flowers evolved in the early Cretaceous period, about 140 million years ago.
A flower is a complex reproductive structure that bears seeds within protective chambers called ovaries.

64. Representatives of Major Angiosperm Clades

65. Figure Flower-pollinator relationships: Scottish broom flower and honeybee (left), hummingbird (top right), baobab tree and bat (bottom right)

66. The Structure of a Flower

67. Generalized Flower Structure

68. Angiosperm Life Cycle

69. The Life Cycle of an Angiosperm