1. Plants, Fungi, and the Move onto Land Ch. 16

2. Overview of land plant evolution There are our main groups of land plants Bryophytes Pteridophytes Gymnosperms Angiosperms

3. Four main groups of land plants 1. Bryophytes – liverworts, hornworts, mosses - Bryophytes have no vascular tissues. -Bryophytes live in damp/moist environments and are small so they don’t need vascular tissue. They are sometimes called “non-vascular plants”.

4. Four main groups of land plants The rest three groups are all vascular plants. Vascular plants have cells that are joined to produce tubes that transport water and nutrients throughout the plant.

5. Except for bryophytes, land plants have vascular tissue in roots, stems, and leaves. - Xylem consists of dead cells that carry water and nutrients from roots to the rest of the plant. - Phloem consists of living cells that distribute sugars and amino acids throughout the plant.

6. The vascular plants are, in order of their evolution:

7. Four main groups of land plants 2. Pteridophytes – ferns, horsetails, lycophytes a. seedless plants, have a vascular system

8. Four main groups of land plants 3. Gymnosperms – conifers, ginkgo, cycads, gnetopsida a. early seed plants b. produce “naked seeds”

9. Four main groups of land plants 4. Angiosperms – flowering plants a. seeds protected by growing in ovaries b. majority of modern plants are in this group

11. Some highlights of plant evolution

12. From aquatic plants to terrestrial plants: charophyceans are that “bridge” Charophyceans - green algae most closely related to land plants. 1. Both charophyceans and land plants are multi-cellular, eukaryotic, photoautotrophs.

13. 2. Both have “rosette cellulose-synthesizing complexes” – rose-shaped arrays of proteins that synthesize the cellulose components that make up plant cell walls. Because all these features are shared between the groups, both land plants and charophyceans must have a common ancestor.

14. Charophyceans, closest algal relatives of the plant kingdom

16. In order to grow on land, the land plants needed to evolve terrestrial adaptations to survive. Terrestrial adaptations can be used to distinguish land plants from charophycean algae. These adaptations are: 1. Apical meristems 2. Multi-cellular, dependent embryos 3. Alternation of generations 4. Spore walls contain sporopollenin 5. Multi-cellular gametangia 6. others…..

17. 1. Apical meristems: these are localized areas of cell division at tips of roots and shoots.

18. 2. Multi-cellular, dependent embryos: Embryo develops within female tissue; female plant provides nutrition (sugars, proteins).

19. 3. Alternation of generations Two multicellular body forms: a. Gametophyte (haploid) that produces gametes. Gametes fuse to form zygotes that develop into… b. Sporophytes (diploid) that produce spores. Spores are haploid cells that can develop into a new organism without fusing with another cell.

20. Alternation of generations: a generalized scheme

21. 4. Spore walls contain sporopollenin a. Sporopollenin is a polymer that makes the walls of plant spores very tough and resistant to harsh conditions. b. Sporopollenin is the most durable organic material known. c. Spores are produced by sporangia (cells in the sporophyte) through the process of meiosis. d. Durable spores are an adaptation for surviving on land. Can withstand long periods of adverse conditions. Easily transported by wind and water.

22. A fern spore

23. 5. Multi-cellular gametangia a. Gametangia are the gametophyte forms of bryophytes, pteridophytes, and gymnosperms. Gametes are produced within these organs. b. Female gametangia are called archegonia  (produce and retain egg cells) c. Male gametangia are called antheridia  (produce sperm)

24. 6. Other terrestrial adaptations common to many land plants: a. Epidermis covered by a waxy cuticle to prevent excess loss of water. b. Pores (stomata) in cell layer can be opened and closed to allow O 2 out and CO 2 in.

25. Cuticle of a stem from Psilotum (a pteridophyte).

26. Origin of land plants A. Theory is that land plants evolved from charophycean algae over 500 million years ago. Evidence: 1. Homologous chloroplasts 2. Homologous cell walls made of cellulose 3. Homologous peroxisomes 4. Similar DNA sequences

27. B. Alternation of generations in plants may have originated by delayed meiosis Zygote  Sporophyte  Many, many spores 1. Occurs on land because it’s more difficult to produce zygotes. (No water for swimming sperm) 2. By producing sporophyte, many gametophytes can be produced from one zygote because many, many spores are produced. This maximizes output of sexual reproduction.

30. C. Adaptations to shallow water pre-adapted plants for living on land 1. Charophycean algae inhabit shallow waters and need to survive when water levels drop. Lead to increasing ability to survive entirely on dry land.

32. Bryophytes A. Gametophyte is the dominant generation in the life cycles of bryophytes

33. Bryophytes

35. B. Life cycle of bryophytes 1. Bryophyte sporophytes produce and disperse huge numbers of spores.

36. The life cycle of Polytrichum, a moss

40. C. Ecological and economic benefits of bryophytes 1. Bryophytes were the world’s only plants for 100 million years. 2. Peat bogs are made mostly of moss called sphagnum. They contain 400 billion tons of carbon and cut down the amount of greenhouse gases. Peat is harvested, dried, and used as a fuel. 3. Sphagnum is harvested for use as a soil conditioner and plant packing material.

41. Sphagnum, or peat moss

44. IV. Origin of vascular plants - Pteridophytes = ferns - Gymnosperms = fir trees - Angiosperms = flowering plants A. Vascular plants evolved additional terrestrial adaptations 1. Xylem and phloem 2. Dominant sporophyte generation independent of the gametophyte  Different from the bryophytes B. Cooksonia evolved over 400 million years ago  oldest known vascular plant

45. Cooksonia, a vascular plant of the Silurian

46. V. Pteridophytes: seedless vascular plants Examples of pteridophytes (seedless vascular plants) – next page…………….

48. A. Pteridophytes provide clues to evolution of roots and leaves 1. There is evidence that roots evolved from subterranean portions of stems. 2. There are two types of leaves: a. Leaves of lycophytes are microphylls. Microphylls are small leaves with a single, unbranched vein. b. Leaves of other modern vascular plants are megaphylls. Megaphylls are typically larger and have a branched vascular system.

49. Hypotheses for the evolution of leaves

51. B. Sporophyte-dominant life cycle evolved in seedless vascular plants (Pteridophytes) 1. Alternation of generations 2. Dominant sporophyte versus dominant gametophyte in bryophytes. 3. Plants are dispersed to new environments as spores; no seeds present

52. The life cycle of a fern

54. Figure 29.24b Fern sporophyll, a leaf specialized for spore production

62. C. Importance of Pteridophytes 1. Dominant plants in Carboniferous period 2. Extensive beds of coal from these plants

63. Artist’s conception of a Carboniferous forest based on fossil evidence

64. The Evolution of Seed Plants: Gymnosperms and Angiosperms

65. Overview of seed plant evolution There were three (3) major reproductive adaptations in the evolution of seed plants. 1)Reduction of gametophyte (Gametophytes of seed plants are microscopic, so they can exist within the sporophyte). 2)Seeds became an important means of dispersal. 3)Pollen (Sperm cells) eliminated the liquid-water requirement for fertilization.

66. 1) Reduction of the gametophyte continued with the evolution of seed plants. In seed plants, the very small female (1N) gametophyte develops from spores retained in the sporangia of the (2N) sporophyte. Why?? Delicate female gametophytes are protected from environmental stress. Embryos that are produced are also protected from stress.

67. Three variations on gametophyte/sporophyte relationships

68. 2) Seeds became an important means of dispersal. Seeds are resistant to environmental stress, and are multi- cellular complex structures that consist of a sporophyte embryo, a food supply, and a protective coat. The embryo develops from the fertilized egg (derived from a spore) retained within the sporangium. The sperm (derived from a spore) is carried (produced by) a pollen grain released from a sporangium.

69. All seed plants are heterosporous. Female spores give rise to female gametes; male spores give rise to male gametes. The megasporangia produce megaspores (female) and the microsporangia produce microspores (male). The megasporangium is enveloped by layers of tissue called integuments. The whole structure (integuments + megasporangium) is called the ovule.

70. From ovule to seed.

71. 3) Pollen (with sperm cells) eliminated the liquid-water requirement for fertilization. Pollen travels by air or on animals. It eliminates the need for water to be present during fertilization.

72. Gymnosperms Gymnosperms are vascular plants that bear naked seeds – seeds not enclosed in specialized chambers. Mesozoic era was the age of gymnosperms Gymnosperms were the most common plants during the Mesozoic era (the age of dinosaurs). Four phyla of extant gymnosperms – Phylum Ginkgophyta: e.g., Ginkgo biloba. – Phylum Cycadophyta: e.g., cycads. – Phylum Gnetophyta: e.g., ephedra – Phylum Coniferophyta: e.g., pines, firs, spruces

83. Life cycle of a pine demonstrates the key reproductive adaptations of seed plants 1. The tree is the sporophyte. 2. Female gametophyte develops within the sporangium. 3. Pollen cone has microsporangium that develops into pollen (male gametophyte). 4. After fertilization, the embryo develops and is surrounded by food reserves and a seed coat. 5. Embryo grows to produce a new sporophyte.

84. The life cycle of a pine.

89. Winged seed of a White Pine (Pinus strobus)

90. Angiosperms are flowering plants that form seeds inside a protective chamber called an ovary. Examples: Monocots: Orchids, lilies, grasses, palms, bamboo (Eu)dicots: Daisies, maples, snapdragon, pea, oaks

91. Angiosperms (Flowering Plants) Systematists are identifying angiosperm clades. Originally, only: Monocots are angiosperms that possess one embryonic seed leaf (cotyledon). Dicots are angiosperms that possess two embryonic seed leaves (cotyledons). However, angiosperms have recently been divided into new taxonomic groups.

92. A comparison of monocots and dicots

94. The flower is the defining reproductive adaptation of angiosperms Flowers are made up of four types of modified leaves  sepals, petals, stamens, and carpels. a. Stamens are the male reproductive organs that produce microspores. b. Carpels are female reproductive organs that produce megaspores.

95. The structure of a flower.

97. A fruit is a mature ovary Protect dormant seeds. Fruit aids in seed dispersal. - Wind dispersal - Attachment and transportation - Consumption – berries contain seeds to be passed in feces

98. Fruit adaptations that enhance seed dispersal

101. Life cycle of an angiosperm Mature plant is the sporophyte Some plants easily self-pollinate, but most have mechanisms to ensure cross-pollination. Male gametophytes reach female gametophytes by producing a pollen tube. Next slide: The life cycle of an angiosperm.

103. Angiosperms dominated the earth at the end of the Mesozoic era Radiation of angiosperms represents the transition from Mesozoic to Cenozoic Angiosperms and animals have affected one another’s evolution Coevolution is the mutual influence on the evolution of two different species interacting with each other and reciprocally influencing each other’s adaptations. e.g., Pollinator-plant relationships

105. Plants and Human Welfare Agriculture is almost totally dependent on angiosperms. Plant diversity is a non-renewable resource. Many medicines are obtained from plant materials.

108. Deforestation is an international practice

111. Deforestation in the United States

112. Fragmentation of a forest ecosystem

113. A sampling of medicines derived from plants

114. Kingdom Fungi Fungi, like plants and animals, are all around us!

115. Fungi are eukaryotic, mostly multicellular, decomposers deriving their nutrition from the absorption of nonliving, decaying organisms Some pathogenic and parasitic fungi acquire nutrition from living hosts

116. Fungal structures The bodies of most fungi are constructed as hyphae=minute threads composed of tubular walls surrounding plasma membranes and cytoplasm These hyphae form a mat of mycelium, the feeding network of fungi 10 cubic centimeters (4 cubic inches) of soil may contain as much as a kilometer (3/4 mile) hyphae

117. Fungal reproduction Fungi reproduce either sexually or asexually by releasing spores carried by water or wind These spores are numerous! When they land on a moist surface with food availability, they then grow

118. Division Basidiomycota: –Reproduce via spores called basidia in a club-like structure called a basidium

119. Division Ascomycota: –Known as sac fungi –Produce spores in a sac called an ascus –75% of all described fungi

120. Lichen: this is a symbiotic relationship between algae and fungus