1. LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson © 2011 Pearson Education, Inc. Lectures by Erin Barley Kathleen Fitzpatrick Plant Diversity I: How Plants Colonized Land Chapter 29

2. Overview: The Greening of Earth For more than the first 3 billion years of Earth’s history, the terrestrial surface was lifeless Cyanobacteria likely existed on land 1.2 billion years ago Around 500 million years ago, small plants, fungi, and animals emerged on land © 2011 Pearson Education, Inc.

3. Since colonizing land, plants have diversified into roughly 290,000 living species Land plants are defined as having terrestrial ancestors, even though some are now aquatic Land plants do not include photosynthetic protists (algae) Plants supply oxygen and are the ultimate source of most food eaten by land animals © 2011 Pearson Education, Inc.

4. 1  m Figure 29.1

5. Concept 29.1: Land plants evolved from green algae Green algae called charophytes are the closest relatives of land plants © 2011 Pearson Education, Inc.

6. Morphological and Molecular Evidence Many characteristics of land plants also appear in a variety of protist clades, mainly algae However, land plants share four key traits with only charophytes – Rings of cellulose-synthesizing complexes – Peroxisome enzymes – Structure of flagellated sperm – Formation of a phragmoplast © 2011 Pearson Education, Inc.

7. 1  m Figure 29.2 30 nm

8. Comparisons of both nuclear and chloroplast genes point to charophytes as the closest living relatives of land plants Note that land plants are not descended from modern charophytes, but share a common ancestor with modern charophytes © 2011 Pearson Education, Inc.

9. 1  m Figure 29.3 Chara species, a pond organism Coleochaete orbicularis, a disk-shaped charophyte that also lives in ponds (LM) 40  m 5 mm

10. 1  m Figure 29.3a Chara species, a pond organism 5 mm

11. 1  m Figure 29.3b Coleochaete orbicularis, a disk-shaped charophyte that lives in ponds (LM) 40  m

12. Adaptations Enabling the Move to Land In charophytes a layer of a durable polymer called sporopollenin prevents exposed zygotes from drying out Sporopollenin is also found in plant spore walls The movement onto land by charophyte ancestors provided unfiltered sun, more plentiful CO 2, nutrient-rich soil, and few herbivores or pathogens Land presented challenges: a scarcity of water and lack of structural support © 2011 Pearson Education, Inc.

13. The accumulation of traits that facilitated survival on land may have opened the way to its colonization by plants Systematists are currently debating the boundaries of the plant kingdom Some biologists think the plant kingdom should be expanded to include some or all green algae Until this debate is resolved, we define plants as embryophytes, plants with embryos © 2011 Pearson Education, Inc.

14. 1  m Figure 29.4 Red algae Chlorophytes Charophytes Embryophytes ANCESTRAL ALGA Viridiplantae Streptophyta Plantae

15. Derived Traits of Plants Four key traits appear in nearly all land plants but are absent in the charophytes – Alternation of generations and multicellular, dependent embryos – Walled spores produced in sporangia – Multicellular gametangia – Apical meristems © 2011 Pearson Education, Inc.

16. Alternation of Generations and Multicellular, Dependent Embryos Plants alternate between two multicellular stages, a reproductive cycle called alternation of generations The gametophyte is haploid and produces haploid gametes by mitosis Fusion of the gametes gives rise to the diploid sporophyte, which produces haploid spores by meiosis © 2011 Pearson Education, Inc.

17. The diploid embryo is retained within the tissue of the female gametophyte Nutrients are transferred from parent to embryo through placental transfer cells Land plants are called embryophytes because of the dependency of the embryo on the parent © 2011 Pearson Education, Inc.

18. 1  m Figure 29.5a Gamete from another plant Key Haploid (n) Diploid (2n) Gametophyte (n) Mitosis Spore Gamete MEIOSIS FERTILIZATION Zygote Mitosis Sporophyte (2n) Alternation of generations 2n2n n n n n

19. 1  m Figure 29.5b Embryo Maternal tissue Embryo (LM) and placental transfer cell (TEM) of Marchantia (a liverwort) Wall ingrowths Placental transfer cell (outlined in blue) 10  m 2  m

20. 1  m Figure 29.5ba Embryo Maternal tissue 10  m

21. 1  m Figure 29.5bb Wall ingrowths Placental transfer cell (outlined in blue) 2  m

22. Walled Spores Produced in Sporangia The sporophyte produces spores in organs called sporangia Diploid cells called sporocytes undergo meiosis to generate haploid spores Spore walls contain sporopollenin, which makes them resistant to harsh environments © 2011 Pearson Education, Inc.

23. 1  m Figure 29.5c Spores Sporangium Longitudinal section of Sphagnum sporangium (LM) Sporophyte Gametophyte Sporophytes and sporangia of Sphagnum (a moss)

24. 1  m Figure 29.5ca Sporangium Sporophyte Gametophyte Sporophytes and sporangia of Sphagnum (a moss)

25. 1  m Figure 29.5cb Spores Sporangium Longitudinal section of Sphagnum sporangium (LM)

26. Multicellular Gametangia Gametes are produced within organs called gametangia Female gametangia, called archegonia, produce eggs and are the site of fertilization Male gametangia, called antheridia, produce and release sperm © 2011 Pearson Education, Inc.

27. 1  m Figure 29.5d Female gametophyte Male gametophyte Archegonia, each with an egg (yellow) Antheridia (brown), containing sperm Archegonia and antheridia of Marchantia (a liverwort)

28. 1  m Figure 29.5da Female gametophyte Male gametophyte

29. Apical Meristems Plants sustain continual growth in their apical meristems Cells from the apical meristems differentiate into various tissues © 2011 Pearson Education, Inc.

30. 1  m Figure 29.5e Apical meristem of shoot Developing leaves Shoot 100  m Root Apical meristem of root Apical meristems of plant roots and shoots

31. 1  m Figure 29.5ea 100  m Root Apical meristem of root

32. 1  m Figure 29.5eb Apical meristem of shoot Developing leaves Shoot 100  m

33. Additional derived traits include – Cuticle, a waxy covering of the epidermis – Mycorrhizae, symbiotic associations between fungi and land plants that may have helped plants without true roots to obtain nutrients – Secondary compounds that deter herbivores and parasites © 2011 Pearson Education, Inc.

34. The Origin and Diversification of Plants Fossil evidence indicates that plants were on land at least 475 million years ago Fossilized spores and tissues have been extracted from 475-million-year-old rocks © 2011 Pearson Education, Inc.

35. 1  m Figure 29.6 (a) Fossilized spores Fossilized sporophyte tissue (b)

36. Figure 29.6a (a) Fossilized spores

37. Figure 29.6b Fossilized sporophyte tissue (b)

38. Those ancestral species gave rise to a vast diversity of modern plants © 2011 Pearson Education, Inc.

39. 1  m Figure 29.7 Origin of land plants (about 475 mya) Origin of vascular plants (about 425 mya) Origin of extant seed plants (about 305 mya) 21321 ANCESTRAL GREEN ALGA 500 450 400 350 30050 0 Millions of years ago (mya) Liverworts Mosses Hornworts Lycophytes (club mosses, spike mosses, quillworts) Pterophytes (ferns, horsetails, whisk ferns) Gymnosperms Angiosperms Land plants Vascular plants Nonvascular plants (bryophytes) Seedless vascular plants Seed plants 3

40. 1  m Figure 29.7a Origin of land plants (about 475 mya) Origin of vascular plants (about 425 mya) Origin of extant seed plants (about 305 mya) 3 ANCESTRAL GREEN ALGA 500 450 400 350 30050 0 Millions of years ago (mya) Liverworts Mosses Hornworts Lycophytes (club mosses, spike mosses, quillworts) Pterophytes (ferns, horsetails, whisk ferns) Gymnosperms Angiosperms 2 1123

41. 1  m Figure 29.7b Liverworts Mosses Hornworts Lycophytes (club mosses, spike mosses, quillworts) Pterophytes (ferns, horsetails, whisk ferns) Gymnosperms Angiosperms Land plants Vascular plants Nonvascular plants (bryophytes) Seedless vascular plants Seed plants

42. Land plants can be informally grouped based on the presence or absence of vascular tissue Most plants have vascular tissue; these constitute the vascular plants Nonvascular plants are commonly called bryophytes Bryophytes are not a monophyletic group; their relationships to each other and to vascular plants are unresolved © 2011 Pearson Education, Inc.

43. Seedless vascular plants can be divided into clades – Lycophytes (club mosses and their relatives) – Pterophytes (ferns and their relatives) Seedless vascular plants are paraphyletic, and are of the same level of biological organization, or grade © 2011 Pearson Education, Inc.

44. A seed is an embryo and nutrients surrounded by a protective coat Seed plants form a clade and can be divided into further clades – Gymnosperms, the “naked seed” plants, including the conifers – Angiosperms, the flowering plants © 2011 Pearson Education, Inc.

45. 1  m Table 29. 1

46. Concept 29.2: Mosses and other nonvascular plants have life cycles dominated by gametophytes Bryophytes are represented today by three phyla of small herbaceous (nonwoody) plants – Liverworts, phylum Hepatophyta – Hornworts, phylum Anthocerophyta – Mosses, phylum Bryophyta Bryophyte refers to all nonvascular plants, whereas Bryophyta refers only to the phylum of mosses © 2011 Pearson Education, Inc.

47. 1  m Figure 29.UN01 Nonvascular plants (bryophytes) Seedless vascular plants Gymnosperms Angiosperms

48. Bryophyte Gametophytes In all three bryophyte phyla, gametophytes are larger and longer-living than sporophytes Sporophytes are typically present only part of the time © 2011 Pearson Education, Inc.

49. Protonemata (n) Key Haploid (n) Diploid (2n) “Bud” Male gametophyte (n) Gametophore Spores Spore dispersal Peristome Female gametophyte (n) Rhizoid Sporangium Seta Capsule (sporangium) Foot MEIOSIS Mature sporophytes 2 mm Capsule with peristome (LM) Female gametophytes 1  m Figure 29.8-1

50. Protonemata (n) Key Haploid (n) Diploid (2n) “Bud” Male gametophyte (n) Antheridia Sperm Egg Archegonia Gametophore Spores Spore dispersal Peristome Female gametophyte (n) Rhizoid FERTILIZATION (within archegonium) Sporangium Seta Capsule (sporangium) Foot MEIOSIS Mature sporophytes 2 mm Capsule with peristome (LM) Female gametophytes 1  m Figure 29.8-2

51. Protonemata (n) Key Haploid (n) Diploid (2n) “Bud” Male gametophyte (n) Antheridia Sperm Egg Archegonia Gametophore Spores Spore dispersal Peristome Sporangium Female gametophyte (n) Rhizoid FERTILIZATION (within archegonium) Zygote (2n) Archegonium Embryo Seta Capsule (sporangium) Foot Young sporophyte (2n) MEIOSIS Mature sporophytes 2 mm Capsule with peristome (LM) Female gametophytes 1  m Figure 29.8-3

52. 1  m Figure 29.8a 2 mm Capsule with peristome (LM)

53. A spore germinates into a gametophyte composed of a protonema and gamete-producing gametophore The height of gametophytes is constrained by lack of vascular tissues Rhizoids anchor gametophytes to substrate Mature gametophytes produce flagellated sperm in antheridia and an egg in each archegonium Sperm swim through a film of water to reach and fertilize the egg © 2011 Pearson Education, Inc.

54. Animation: Moss Life Cycle

55. Bryophyte Sporophytes Bryophyte sporophytes grow out of archegonia, and are the smallest and simplest sporophytes of all extant plant groups A sporophyte consists of a foot, a seta (stalk), and a sporangium, also called a capsule, which discharges spores through a peristome Hornwort and moss sporophytes have stomata for gas exchange; liverworts do not © 2011 Pearson Education, Inc.

56. 1  m Figure 29.9a Sporophyte Thallus Gametophore of female gametophyte Marchantia polymorpha, a “thalloid” liverwort Marchantia sporophyte (LM) Foot Seta Capsule (sporangium) 500  m Plagiochila deltoidea, a “leafy” liverwort

57. 1  m Figure 29.9aa Thallus Gametophore of female gametophyte Marchantia polymorpha, a “thalloid” liverwort

58. 1  m Figure 29.9ab Marchantia sporophyte (LM) Foot Seta Capsule (sporangium) 500  m

59. 1  m Figure 29.9ac Plagiochila deltoidea, a “leafy” liverwort

60. 1  m Figure 29.9b An Anthoceros hornwort species Sporophyte Gametophyte

61. 1  m Figure 29.9c Polytrichum commune, hairy-cap moss Capsule Seta Sporophyte (a sturdy plant that takes months to grow) Gametophyte

62. The Ecological and Economic Importance of Mosses Mosses are capable of inhabiting diverse and sometimes extreme environments, but are especially common in moist forests and wetlands Some mosses might help retain nitrogen in the soil © 2011 Pearson Education, Inc.

63. 1  m Figure 29.10 With moss Without moss RESULTS Annual nitrogen loss (kg/ha) 6 5 4 3 2 1 0

64. Sphagnum, or “peat moss,” forms extensive deposits of partially decayed organic material known as peat Peat can be used as a source of fuel Sphagnum is an important global reservoir of organic carbon Overharvesting of Sphagnum and/or a drop in water level in peatlands could release stored CO 2 to the atmosphere © 2011 Pearson Education, Inc.

65. 1  m Figure 29.11 Peat being harvested from a peatland (a)“Tollund Man,” a bog mummy dating from 405–100 B.C.E. (b)

66. 1  m Figure 29.11a (a) Peat being harvested from a peatland

67. 1  m Figure 29.11b “Tollund Man,” a bog mummy dating from 405–100 B.C.E. (b)

68. Concept 29.3: Ferns and other seedless vascular plants were the first plants to grow tall Bryophytes and bryophyte-like plants were the prevalent vegetation during the first 100 million years of plant evolution Vascular plants began to diversify during the Devonian and Carboniferous periods Vascular tissue allowed these plants to grow tall Seedless vascular plants have flagellated sperm and are usually restricted to moist environments © 2011 Pearson Education, Inc.

69. 1  m Figure 29.UN03 Nonvascular plants (bryophytes) Seedless vascular plants Gymnosperms Angiosperms

70. Origins and Traits of Vascular Plants Fossils of the forerunners of vascular plants date back about 425 million years These early tiny plants had independent, branching sporophytes Living vascular plants are characterized by  Life cycles with dominant sporophytes  Vascular tissues called xylem and phloem  Well-developed roots and leaves © 2011 Pearson Education, Inc.

71. 1  m Figure 29.12 Sporangia

72. Life Cycles with Dominant Sporophytes In contrast with bryophytes, sporophytes of seedless vascular plants are the larger generation, as in familiar ferns The gametophytes are tiny plants that grow on or below the soil surface © 2011 Pearson Education, Inc. Animation: Fern Life Cycle

73. 1  m Figure 29.13-1 Key Haploid (n) Diploid (2n) MEIOSIS Spore dispersal Mature sporophyte (2n) Fiddlehead (young leaf) Sporangium Sorus Sporangium

74. 1  m Figure 29.13-2 Key Haploid (n) Diploid (2n) MEIOSIS Spore dispersal Spore (n) Young gametophyte Rhizoid Underside of mature gametophyte (n) Antheridium Sperm Archegonium Egg FERTILIZATION Mature sporophyte (2n) Fiddlehead (young leaf) Sporangium Sorus Sporangium

75. 1  m Figure 29.13-3 Key Haploid (n) Diploid (2n) MEIOSIS Spore dispersal Spore (n) Young gametophyte Rhizoid Underside of mature gametophyte (n) Antheridium Sperm Archegonium Egg FERTILIZATION Zygote (2n) Gametophyte New sporophyte Mature sporophyte (2n) Fiddlehead (young leaf) Sporangium Sorus Sporangium

76. Transport in Xylem and Phloem Vascular plants have two types of vascular tissue: xylem and phloem Xylem conducts most of the water and minerals and includes dead cells called tracheids Water-conducting cells are strengthened by lignin and provide structural support Phloem consists of living cells and distributes sugars, amino acids, and other organic products Vascular tissue allowed for increased height, which provided an evolutionary advantage © 2011 Pearson Education, Inc.

77. Evolution of Roots Roots are organs that anchor vascular plants They enable vascular plants to absorb water and nutrients from the soil Roots may have evolved from subterranean stems © 2011 Pearson Education, Inc.

78. Evolution of Leaves Leaves are organs that increase the surface area of vascular plants, thereby capturing more solar energy that is used for photosynthesis Leaves are categorized by two types  Microphylls, leaves with a single vein  Megaphylls, leaves with a highly branched vascular system © 2011 Pearson Education, Inc.

79. According to one model of evolution, microphylls evolved as outgrowths of stems Megaphylls may have evolved as webbing between flattened branches © 2011 Pearson Education, Inc.

80. 1  m Figure 29.14 Vascular tissue Sporangia Microphyll (a) Microphylls (b) Megaphylls Overtopping growth Megaphyll Other stems become reduced and flattened. Webbing develops.

81. 1  m Figure 29.14a Vascular tissue Sporangia Microphyll (a) Microphylls

82. 1  m Figure 29.14b (b) Megaphylls Overtopping growth Megaphyll Other stems become reduced and flattened. Webbing develops.

83. Sporophylls and Spore Variations Sporophylls are modified leaves with sporangia Sori are clusters of sporangia on the undersides of sporophylls Strobili are cone-like structures formed from groups of sporophylls © 2011 Pearson Education, Inc.

84. Most seedless vascular plants are homosporous, producing one type of spore that develops into a bisexual gametophyte All seed plants and some seedless vascular plants are heterosporous Heterosporous species produce megaspores, which give rise to female gametophytes, and microspores, which give rise to male gametophytes © 2011 Pearson Education, Inc.

85. Classification of Seedless Vascular Plants There are two phyla of seedless vascular plants – Phylum Lycophyta includes club mosses, spike mosses, and quillworts – Phylum Pterophyta includes ferns, horsetails, and whisk ferns and their relatives © 2011 Pearson Education, Inc.

86. 1  m Figure 29.15a Selaginella moellendorffii, a spike moss Isoetes gunnii, a quillwort Diphasiastrum tristachyum, a club moss Strobili (clusters of sporophylls) 2.5 cm 1 cm

87. 1  m Figure 29.15aa Selaginella moellendorffii, a spike moss 1 cm

88. 1  m Figure 29.15ab Isoetes gunnii, a quillwort

89. 1  m Figure 29.15ac Diphasiastrum tristachyum, a club moss Strobili (clusters of sporophylls) 2.5 cm

90. Athyrium filix-femina, lady fern Equisetum arvense, field horsetail Vegetative stem Psilotum nudum, a whisk fern 4 cm 25 cm 1.5 cm Figure 29.15b

91. 1  m Figure 29.15ba Athyrium filix-femina, lady fern 25 cm

92. Equisetum arvense, field horsetail Vegetative stem 1.5 cm Figure 29.15bb

93. 1  m Figure 29.15bc Psilotum nudum, a whisk fern 4 cm

94. Phylum Lycophyta: Club Mosses, Spike Mosses, and Quillworts Giant lycophytes trees thrived for millions of years in moist swamps Surviving species are small herbaceous plants Club mosses and spike mosses have vascular tissues and are not true mosses © 2011 Pearson Education, Inc.

95. Phylum Pterophyta: Ferns, Horsetails, and Whisk Ferns and Relatives Ferns are the most diverse seedless vascular plants, with more than 12,000 species They are most diverse in the tropics but also thrive in temperate forests Horsetails were diverse during the Carboniferous period, but are now restricted to the genus Equisetum Whisk ferns resemble ancestral vascular plants but are closely related to modern ferns © 2011 Pearson Education, Inc.

96. The Significance of Seedless Vascular Plants The ancestors of modern lycophytes, horsetails, and ferns grew to great heights during the Devonian and Carboniferous, forming the first forests Increased growth and photosynthesis removed CO 2 from the atmosphere and may have contributed to global cooling at the end of the Carboniferous period The decaying plants of these Carboniferous forests eventually became coal © 2011 Pearson Education, Inc.

97. Fern Lycophyte trees Horsetail Tree trunk covered with small leaves Lycophyte tree reproductive structures 1  m Figure 29.16

98. 1  m Figure 29.UN02

99. 1  m Figure 29.UN04 Homosporous spore production Heterosporous spore production Sporangium on sporophyll Single type of spore Typically a bisexual gametophyte Eggs Sperm Megasporangium on megasporophyll Megaspore Female gametophyte Male gametophyte Eggs Sperm Microspore Microsporangium on microsporophyll

100. Gametophyte Mitosis Spore Gamete MEIOSIS FERTILIZATION Zygote Mitosis Sporophyte Haploid Diploid Alternation of generations 4 2 1 3 Apical meristem of shoot Developing leaves Apical meristems Archegonium with egg Antheridium with sperm Sporangium Spores Multicellular gametangia Walled spores in sporangia n n n n 2n2n 1  m Figure 29.UN05

101. 1  m Figure 29.UN05a Gametophyte Mitosis Spore Gamete MEIOSIS FERTILIZATION Zygote Mitosis Sporophyte Haploid Diploid Alternation of generations 1 n n n n 2n2n

102. 1  m Figure 29.UN05b Apical meristem of shoot Developing leaves Apical meristems 2

103. 1  m Figure 29.UN05c Archegonium with egg Antheridium with sperm Multicellular gametangia 3

104. 1  m Figure 29.UN05d Sporangium Spores Walled spores in sporangia 4

105. 1  m Figure 29.UN06

106. 1  m Figure 29.UN07

107. 1  m Figure 29.UN08

108. 1  m Figure 29.UN09

109. 1  m Figure 29.UN10