1. Evolution and Diversity of Plants
Chapter 24
Mader: Biology 8th Ed.

2. Alternation of Generations Nonvascular Plants Vascular Plants Seedless
Outline
Evolutionary History
Alternation of Generations
Nonvascular Plants
Vascular Plants
Seedless
Seed
Angiosperms
Monocots and Eudicots
Flowers
Mader: Biology 8th Ed.

3. Evolutionary History of Plants
Plants are thought to have evolved from freshwater algae over 500 mya.
Evolution of plants marked by four evolutionary events associated with four major groups of plants.
Nonvascular Plants
Advent of nourishment of a multicellular embryo within the body of the female plant.
Mader: Biology 8th Ed.

4. Evolutionary History of Plants
Seedless vascular plants
Advent of vascular tissue.
Gymnosperms and angiosperms
Produce seeds.
Flowering Plants
Attract pollinators that give rise to fruits.
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5. Four Major Plant Groups
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6. Alternation of Generations
All plants have a life cycle that includes an alternation of generations.
Two multicellular individuals alternate, each producing the other.
Sporophyte represents diploid generation.
Gametophyte represents haploid generation.
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7. Alternation of Generations
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8. Alternation of Generations
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9. Alternation of Generations
Sporophyte (2n) is named for its production of spores by meiosis.
Spore is haploid reproductive cell.
Gametophyte (n) is named for its production of gametes.
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10. Reduction in Size of Gametophyte
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11. Alternation of Generations
Appearance of generations varies widely.
In ferns, female portions are archegonia and are fertilized by flagellated sperm.
In angiosperm, female gametophyte (embryo sac), consists of an ovule.
Following fertilization, ovule becomes seed.
In seed plants, pollen grains are mature sperm-bearing male gametophytes.
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12. Protection of Eggs and Embryos
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13. Other Terrestrial Adaptations
Vascular tissue transports water and nutrients to the body of the plant.
Cuticle provides an effective barrier to water loss.
Stomata bordered by guard cells that regulate opening, and thus water loss.
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14. Leaves of Vascular Plants
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15. Do not have true roots, stems, and leaves.
Nonvascular Plants
Nonvascular plants (bryophytes) lack specialized means of transporting water and organic nutrients.
Do not have true roots, stems, and leaves.
Gametophyte is dominant generation.
Produces eggs in archegonia and flagellated sperm in antheridia.
Sperm swim to egg in film of water.
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16. Nonvascular Plants
Hornworts (phlym Anthocerophyta) have small sporophytes that carry on photosynthesis.
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17. Nonvascular Plants
Liverworts (phylum Hepatophyta) have either flattened thallus or leafy appearance.
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18. Can reproduce asexually by fragmentation.
Nonvascular Plants
Mosses (phylum Bryophyta) usually have a leafy shoot, although some are secondarily flattened.
Can reproduce asexually by fragmentation.
Dependent sporophyte consists of foot, stalk, and sporangium.
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19. Moss Life Cycle
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20. Xylem conducts water and dissolved minerals up from roots.
Vascular Plants
Xylem conducts water and dissolved minerals up from roots.
Phloem conducts sucrose and other organic compounds throughout the plant.
Lignin strengthens walls of conducting cells in xylem.
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21. Vascular Tissue
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22. Most seedless vascular plants are homosporous.
Windblown spores are dispersal agents.
All seed plants are heterosporous and have male and female gametophytes.
Seeds disperse offspring.
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23. Seedless Vascular Plants
Club Mosses (phylum Lycophyta)
Typically, branching rhizome sends up short aerial stems.
Leaves are microphylls (have only one strand of vascular tissue).
Sporangia occur on surfaces of sporophylls.
Grouped into club-shaped strobili.
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24. Club Mosses
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25. Seedless Vascular Plants
Ferns and Allies
Horsetails (phylum Sphenophyta)
Rhizome produces tall aerial stems.
Contains whorls of slender, green branches.
Small, scalelike leaves also form whorls at the joints.
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26. Horsetail
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27. Whisk Ferns (phylum Psilotophyta) Branched rhizome has rhizoids.
Mutualistic mycorrhizal fungus helps gather nutrients.
Ferns (phylum Pterophyta)
Large conspicuous fronds.
Divided into leaflets.
Dominant sporophyte produces windblown spores.
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28. Whisk Ferns and Ferns
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29. Fern Life Cycle
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30. Fern Life Cycle
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31. Seed plants are the most plentiful plants in the biosphere.
Seed coat and stored food allow an embryo to survive harsh conditions during long period of dormancy.
Heterosporous
Drought-resistant pollen grains.
Ovule develops into seed.
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32. Gymnosperms
Gymnosperms have ovules and seeds exposed on the surface of sporophylls.
Confiers
Cycads
Ginkgoes
Gnetophytes
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33. Conifers, as well as other gymnosperm phyla, bear cones.
Tough, needlelike leaves of pines conserve water with a thick cuticle and recessed stomata.
Considered a “soft” wood because it consists primarily of xylem tissue.
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34. Conifers
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35. Pine Life Cycle
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36. Pine Life Cycle
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37. Pollen and seed cones on separate plants. Pollinated by insects.
Cycads
Cycads (phylum Cycadophyta) have large, finely divided leaves that grow in clusters at the top of the stem.
Pollen and seed cones on separate plants.
Pollinated by insects.
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38. One surviving species. (Gingko biloba)
Ginkgoes
Ginkgoes (phylum Ginkgophyta) are dioecious, with some trees producing seeds and others producing pollen.
One surviving species. (Gingko biloba)
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39. Gnetophytes
Gnetophytes (phylum Gnetophyta) have similarly structured xylem, while none have archegonia, but strobili have similar construction.
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40. Ovules are always enclosed within diploid tissues.
Angiosperms
Angiosperms (phylum Anthophyta) are an exceptionally large and successful group of plants.
Ovules are always enclosed within diploid tissues.
Became dominant group of plants in the late Cretaceous and early Paleogene periods.
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41. Two classes of flowering plants. Monocotyledones (Monocots)
Monocots and Eudicots
Two classes of flowering plants.
Monocotyledones (Monocots)
One cotyledon in seed.
Eudicotyledones (Dicots)
Two cotyledons in seed.
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42. Penducle (flower stalk) expands at tip into a receptacle.
The Flower
Penducle (flower stalk) expands at tip into a receptacle.
Bears sepals, petals, stamens, and carpels, all attached to receptacle in whorls.
Calyx (collection of sepals) protect flower bud before it opens.
Corolla (collection of petals).
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43. Each stamen consists of an anther and a filament (stalk).
The Flower
Each stamen consists of an anther and a filament (stalk).
Carpel has three major regions.
Ovary - Swollen base.
Fruit
Style - Elevates stigma.
Stigma - Sticky receptor of pollen grains.
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44. Mader: Biology 8th Ed.

45. Flowering Plant Life Cycle
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46. Flowering Plant Life Cycle
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47. Flowers and Diversification
Wind-pollinated flowers are usually not showy.
Bird-pollinated flowers are often colorful.
Night-blooming flowers attract nocturnal mammals or insects.
Usually white or cream-colored.
Fruits of flowers protect and aid in dispersal.
Utilize wind, gravity, water, and animals for dispersal.
Mader: Biology 8th Ed.

48. Alternation of Generations Nonvascular Plants Vascular Plants Seedless
Review
Evolutionary History
Alternation of Generations
Nonvascular Plants
Vascular Plants
Seedless
Seed
Angiosperms
Monocots and Eudicots
Flowers
Mader: Biology 8th Ed.

49. Mader: Biology 8th Ed.