Plants and the Move onto Land

Plants and the Move onto Land
Chapter 16 Plants and the Move onto Land

Terrestrial Adaptations of Plants Structural Adaptations
A plant is A multicellular eukaryote A photoautotroph, making organic molecules by photosynthesis Plants are terrestrial organisms that include forms that have returned to water, such as water lilies. Student Misconceptions and Concerns 1. Students often misunderstand evolution as a deliberate and directed process. This chapter provides good examples of how evolution actually occurs. The American chestnut trees were driven nearly to extinction because they did not possess the adaptations that would have helped them to survive the blight fungus. If evolution involved acquiring needed adaptations, why then would the chestnuts suffer? As plants evolved onto land, the properties of a terrestrial environment selected amongst the diversity of the species that existed. For example, plants that produced leaves with more wax had the advantage of greater water retention. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations evolved in plants that already had the traits that permitted them to invade this new environment. 2. The text discusses charophytes as the group most closely related to plants. Students might misinterpret this to mean that modern charophyceans were the direct ancestors of plants. Instead, modern charophyceans and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Teaching Tips 1. Consider challenging your students to suggest the new demands of living on land. They could work in small groups in class or outside of class and their responses to you. By asking them to consider the challenges that plants (and in the next chapter, animals) face when they moved onto land prepares them for the discussions of the adaptations that resulted and are discussed in Chapter 16. 2. The authors make a connection between water lilies and whales, because both are aquatic organisms that evolved from terrestrial forms. 3. Point out to your students that in an aquatic environment resources (such as nutrients and water) are exposed to nearly the entire plant. However, on land, structural specializations have evolved because resources are no longer evenly exposed to the plant (roots are subterranean adaptations and shoots are aerial adaptations). 4. Consider the analogy between vascular systems in plants and a major interstate highway, with traffic running in opposite directions. 5. Have your students discuss the specific advantages of similar adaptations in the reproductive systems of plants and mammals. What are the advantages to keeping the developing embryos with the parent? (For example: The embryonic environment can be carefully regulated by the parent and the parent can better protect the young from damage, disease, or predation.) © 2010 Pearson Education, Inc.

In terrestrial habitats, the resources that a photosynthetic organism needs are found in two very different places: Light and carbon dioxide are mainly available in the air Water and mineral nutrients are found mainly in the soil The complex bodies of plants are specialized to take advantage of these two environments by having Aerial leaf-bearing organs called shoots Subterranean organs called roots Student Misconceptions and Concerns 1. Students often misunderstand evolution as a deliberate and directed process. This chapter provides good examples of how evolution actually occurs. The American chestnut trees were driven nearly to extinction because they did not possess the adaptations that would have helped them to survive the blight fungus. If evolution involved acquiring needed adaptations, why then would the chestnuts suffer? As plants evolved onto land, the properties of a terrestrial environment selected amongst the diversity of the species that existed. For example, plants that produced leaves with more wax had the advantage of greater water retention. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations evolved in plants that already had the traits that permitted them to invade this new environment. 2. The text discusses charophytes as the group most closely related to plants. Students might misinterpret this to mean that modern charophyceans were the direct ancestors of plants. Instead, modern charophyceans and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Teaching Tips 1. Consider challenging your students to suggest the new demands of living on land. They could work in small groups in class or outside of class and their responses to you. By asking them to consider the challenges that plants (and in the next chapter, animals) face when they moved onto land prepares them for the discussions of the adaptations that resulted and are discussed in Chapter 16. 2. The authors make a connection between water lilies and whales, because both are aquatic organisms that evolved from terrestrial forms. 3. Point out to your students that in an aquatic environment resources (such as nutrients and water) are exposed to nearly the entire plant. However, on land, structural specializations have evolved because resources are no longer evenly exposed to the plant (roots are subterranean adaptations and shoots are aerial adaptations). 4. Consider the analogy between vascular systems in plants and a major interstate highway, with traffic running in opposite directions. 5. Have your students discuss the specific advantages of similar adaptations in the reproductive systems of plants and mammals. What are the advantages to keeping the developing embryos with the parent? (For example: The embryonic environment can be carefully regulated by the parent and the parent can better protect the young from damage, disease, or predation.)

Plant Alga Reproductive structures (such as those in flowers)
contain spores and gametes Plant Leaf performs photosynthesis Cuticle reduces water loss; stomata regulate gas exchange Shoot supports plant (and may perform photosynthesis) Alga Whole alga performs photosynthesis; absorbs water, CO2, and minerals from the water Figure 16.1 Structural adaptations of algae and plants Surrounding water supports the alga Roots anchor plant; absorb water and minerals from the soil (aided by fungi) Figure 16.1

Most plants have mycorrhizae, symbiotic fungi associated with their roots, in which the fungi
Absorb water and essential minerals from the soil Provide these materials to the plant Are nourished by sugars produced by the plant Student Misconceptions and Concerns 1. Students often misunderstand evolution as a deliberate and directed process. This chapter provides good examples of how evolution actually occurs. The American chestnut trees were driven nearly to extinction because they did not possess the adaptations that would have helped them to survive the blight fungus. If evolution involved acquiring needed adaptations, why then would the chestnuts suffer? As plants evolved onto land, the properties of a terrestrial environment selected amongst the diversity of the species that existed. For example, plants that produced leaves with more wax had the advantage of greater water retention. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations evolved in plants that already had the traits that permitted them to invade this new environment. 2. The text discusses charophytes as the group most closely related to plants. Students might misinterpret this to mean that modern charophyceans were the direct ancestors of plants. Instead, modern charophyceans and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Teaching Tips 1. Consider challenging your students to suggest the new demands of living on land. They could work in small groups in class or outside of class and their responses to you. By asking them to consider the challenges that plants (and in the next chapter, animals) face when they moved onto land prepares them for the discussions of the adaptations that resulted and are discussed in Chapter 16. 2. The authors make a connection between water lilies and whales, because both are aquatic organisms that evolved from terrestrial forms. 3. Point out to your students that in an aquatic environment resources (such as nutrients and water) are exposed to nearly the entire plant. However, on land, structural specializations have evolved because resources are no longer evenly exposed to the plant (roots are subterranean adaptations and shoots are aerial adaptations). 4. Consider the analogy between vascular systems in plants and a major interstate highway, with traffic running in opposite directions. 5. Have your students discuss the specific advantages of similar adaptations in the reproductive systems of plants and mammals. What are the advantages to keeping the developing embryos with the parent? (For example: The embryonic environment can be carefully regulated by the parent and the parent can better protect the young from damage, disease, or predation.)

Roots Fungus Root surrounded by fungus Figure 16.2
Figure 16.2 Mycorrhizae: symbiotic associations of fungi and roots. Root surrounded by fungus Figure 16.2

Leaves are the main photosynthetic organs of most plants, with
Stomata for the exchange of carbon dioxide and oxygen with the atmosphere Vascular tissue for transporting vital materials A waxy cuticle surface that helps the plant retain water Student Misconceptions and Concerns 1. Students often misunderstand evolution as a deliberate and directed process. This chapter provides good examples of how evolution actually occurs. The American chestnut trees were driven nearly to extinction because they did not possess the adaptations that would have helped them to survive the blight fungus. If evolution involved acquiring needed adaptations, why then would the chestnuts suffer? As plants evolved onto land, the properties of a terrestrial environment selected amongst the diversity of the species that existed. For example, plants that produced leaves with more wax had the advantage of greater water retention. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations evolved in plants that already had the traits that permitted them to invade this new environment. 2. The text discusses charophytes as the group most closely related to plants. Students might misinterpret this to mean that modern charophyceans were the direct ancestors of plants. Instead, modern charophyceans and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Teaching Tips 1. Consider challenging your students to suggest the new demands of living on land. They could work in small groups in class or outside of class and their responses to you. By asking them to consider the challenges that plants (and in the next chapter, animals) face when they moved onto land prepares them for the discussions of the adaptations that resulted and are discussed in Chapter 16. 2. The authors make a connection between water lilies and whales, because both are aquatic organisms that evolved from terrestrial forms. 3. Point out to your students that in an aquatic environment resources (such as nutrients and water) are exposed to nearly the entire plant. However, on land, structural specializations have evolved because resources are no longer evenly exposed to the plant (roots are subterranean adaptations and shoots are aerial adaptations). 4. Consider the analogy between vascular systems in plants and a major interstate highway, with traffic running in opposite directions. 5. Have your students discuss the specific advantages of similar adaptations in the reproductive systems of plants and mammals. What are the advantages to keeping the developing embryos with the parent? (For example: The embryonic environment can be carefully regulated by the parent and the parent can better protect the young from damage, disease, or predation.)

Phloem Vascular tissue Xylem Oak leaf Figure 16.3
Figure 16.3 Network of vascular tissue in a leaf. Oak leaf Figure 16.3

Vascular tissue in plants is also found in the
Roots Shoots Two types of vascular tissue exist in plants: Xylem transports water and minerals from roots to leaves Phloem distributes sugars from leaves to the roots and other nonphotosynthetic parts of the plant Student Misconceptions and Concerns 1. Students often misunderstand evolution as a deliberate and directed process. This chapter provides good examples of how evolution actually occurs. The American chestnut trees were driven nearly to extinction because they did not possess the adaptations that would have helped them to survive the blight fungus. If evolution involved acquiring needed adaptations, why then would the chestnuts suffer? As plants evolved onto land, the properties of a terrestrial environment selected amongst the diversity of the species that existed. For example, plants that produced leaves with more wax had the advantage of greater water retention. Plants did not evolve adaptations to address the needs of living on land. Instead, terrestrial adaptations evolved in plants that already had the traits that permitted them to invade this new environment. 2. The text discusses charophytes as the group most closely related to plants. Students might misinterpret this to mean that modern charophyceans were the direct ancestors of plants. Instead, modern charophyceans and plants share a common ancestor, but each has been evolving since the lineages diverged. This same confusion occurs when considering the evolutionary history of humans and chimps. Humans and chimps share a common ancestor. Modern humans did not evolve from modern chimps. Teaching Tips 1. Consider challenging your students to suggest the new demands of living on land. They could work in small groups in class or outside of class and their responses to you. By asking them to consider the challenges that plants (and in the next chapter, animals) face when they moved onto land prepares them for the discussions of the adaptations that resulted and are discussed in Chapter 16. 2. The authors make a connection between water lilies and whales, because both are aquatic organisms that evolved from terrestrial forms. 3. Point out to your students that in an aquatic environment resources (such as nutrients and water) are exposed to nearly the entire plant. However, on land, structural specializations have evolved because resources are no longer evenly exposed to the plant (roots are subterranean adaptations and shoots are aerial adaptations). 4. Consider the analogy between vascular systems in plants and a major interstate highway, with traffic running in opposite directions. 5. Have your students discuss the specific advantages of similar adaptations in the reproductive systems of plants and mammals. What are the advantages to keeping the developing embryos with the parent? (For example: The embryonic environment can be carefully regulated by the parent and the parent can better protect the young from damage, disease, or predation.)

(1) About 475 million years ago plants originated from an algal ancestor giving rise to bryophytes, nonvascular plants, including mosses, liverworts, and hornworts that are nonvascular plants without Lignified walls True roots True leaves Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

(2) About 425 million years ago ferns evolved
With vascular tissue hardened with lignin But without seeds Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

(3) About 360 million years ago gymnosperms evolved with seeds that consisted of an embryo packaged along with a store of food within a protective covering but not enclosed in any specialized chambers. Today, conifers, consisting mainly of cone-bearing trees such as pines, are the most diverse and widespread gymnosperms. Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

(4) About 140 million years ago angiosperms evolved with complex reproductive structures called flowers that bear seeds within protective chambers called ovaries. Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

The great majority of living plants
Are angiosperms Include fruit and vegetable crops, grains, grasses, and most trees Are represented by more than 250,000 species Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

(seedless vascular plants)
PLANT DIVERSITY Bryophytes (nonvascular plants) Ferns (seedless vascular plants) Gymnosperms (naked-seed plants) Angiosperms (flowering plants) Figure 16.7 The major groups of plants Figure 16.7

Bryophytes Bryophytes, most commonly mosses
Sprawl as low mats over acres of land Need water to reproduce because their sperm swim to reach eggs within the female gametangium Have two key terrestrial adaptations: A waxy cuticle that helps prevent dehydration The retention of developing embryos within the mother plant’s gametangium Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Figure 16.8 A peat moss bog in Scotland

Mosses have two distinct forms:
The gametophyte, which produces gametes The sporophyte, which produces spores Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Spores Spore capsule Sporophyte Gametophytes Figure 16.9
Figure 16.9 The two forms of a moss Gametophytes Figure 16.9

The life cycle of a moss exhibits an alternation of generations shifting between the gametophyte and sporophyte forms. Mosses and other bryophytes are unique in having the gametophyte as the larger, more obvious plant. Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Gametes: sperm and eggs (n) Spores (n) Gametophyte (n) Spore capsule
osis Mit osis Mit Gametes: sperm and eggs (n) Spores (n) Gametophyte (n) MEIOSIS FERTILIZATION Spore capsule Zygote (2n) Sporophyte (2n) t o Mi sis Figure Alternation of generations (Step 5) Key Haploid (n) Diploid (2n) Figure

Ferns Ferns are The sperm of ferns, like those of mosses
Seedless vascular plants By far the most diverse with more than 12,000 known species The sperm of ferns, like those of mosses Have flagella Must swim through a film of water to fertilize eggs Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Spore capsule “Fiddlehead” (young leaves ready to unfurl) Figure 16.11
Figure Ferns (seedless vascular plants) Spore capsule “Fiddlehead” (young leaves ready to unfurl) Figure 16.11

Conifers Conifers Cover much of northern Eurasia and North America
Are usually evergreens, which retain their leaves throughout the year Include the tallest, largest, and oldest organisms on Earth Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Figure 16.13 A coniferous forest in Banff National Park, in Alberta, Canada

Terrestrial Adaptations of Seed Plants
Conifers and most other gymnosperms have three additional terrestrial adaptations: Further reduction of the gametophyte Pollen Seeds A pine tree or other conifer is actually a sporophyte with tiny gametophytes living in cones. Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Scale Ovule-producing cones; the scales contain female gametophytes
Pollen-producing cones; they produce male gametophytes Figure A pine tree, the sporophyte, bearing two types of cones containing gametophytes Ponderosa pine Figure 16.15

A second adaptation of seed plants to dry land was the evolution of pollen.
A pollen grain Is actually the much-reduced male gametophyte Houses cells that will develop into sperm The third terrestrial adaptation was the development of the seed, consisting of A plant embryo A food supply packaged together within a protective coat Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Seeds Develop from structures called ovules, located on the scales of female cones in conifers Can remain dormant for long periods before they germinate, as the embryo emerges through the seed coat as a seedling Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Haploid (n) Diploid (2n) (a) Ovule (b) Fertilized ovule (c) Seed
Female cone, cross section Cross section of scale Integument Spore case (a) Ovule Spore Egg nucleus Spore case Female gametophyte (b) Fertilized ovule Pollen tube Discharged sperm nucleus Figure From ovule to seed (Step 3) Pollen grain (male gametophyte) Seed coat (derived from integument) (c) Seed Food supply (derived from female gametophyte tissue) Embryo (new sporophyte) Figure

Angiosperms Angiosperms Their success is largely due to
Dominate the modern landscape Are represented by about 250,000 species Supply nearly all of our food and much of our fiber for textiles Their success is largely due to A more efficient water transport The evolution of the flower Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Flowers, Fruits, and the Angiosperm Life Cycle
Flowers help to attract pollinators who transfer pollen from the sperm-bearing organs of one flower to the egg-bearing organs of another. A flower is actually a short stem with four whorls of modified leaves: Sepals Petals Stamens Carpels Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Petal Stigma Anther Stamen Carpel Style Filament Ovary Ovule Sepal
Figure Structure of a flower Ovule Sepal Figure 16.17

Pansy Bleeding heart California poppy Water lily Figure 16.18
Figure A diversity of flowers Pansy Bleeding heart California poppy Water lily Figure 16.18

Figure 16.19-6 Germinated pollen grain (male gametophyte) on
stigma of carpel Anther at tip of stamen Pollen tube growing down style of carpel Mature sporophyte plant with flowers Ovary (base of carpel) Ovule FERTILIZATION Endosperm Embryo sac (female gametophyte) Egg Zygote Two sperm nuclei Sporophyte seedling Figure The angiosperm life cycle (Step 6) Embryo (sporophyte) Seed Germinating seed Key Haploid (n) Diploid (2n) Seed (develops from ovule) Fruit (develops from ovary) Figure

Although both have seeds
Angiosperms enclose the seed within an ovary Gymnosperms have naked seeds Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Fruit Is a ripened ovary Helps protect the seed
Increases seed dispersal Is a major food source for animals Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Wind dispersal Animal transportation Animal ingestion Figure 16.20
Figure Fruits and seed dispersal Figure 16.20

Angiosperms and Agriculture
Gymnosperms supply most of our lumber and paper. Angiosperms Provide nearly all our food Supply fiber, medications, perfumes, and decoration Agriculture is a unique kind of evolutionary relationship between plants and animals. The exploding human population is Extinguishing plant species at an unprecedented rate Destroying fifty million acres, an area the size of the state of Washington, every year! Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Figure 16.21 Clear-cutting of a tropical forest in Brazil

Humans depend on plants for thousands of products including
Food Building materials Medicines Student Misconceptions and Concerns 1. Students can easily confuse animal and plant reproductive cycles. However, the unique inclusion of alternation of generations in plants (and certain algae) makes analogies and parallels challenging and potentially confusing when referencing animal life cycles. 2. Students often confuse global warming and the destruction of the ozone layer. This might be a good time to discuss or clarify global warming. The carbon removed from the air in the Carboniferous has been “locked up” in coal for about 300 million years. By burning fossil fuels, we are reintroducing carbon that has been “out of circulation.” Thus, there is a net gain in global carbon dioxide, which may act like glass in a car to reflect back heat (or glass in a greenhouse). Note that burning ethanol derived from corn does not directly contribute to global warming because the carbon in the ethanol was removed from the air only a year or two ago, instead of hundreds of millions of years ago (although the use of fossil fuels to raise, harvest, and process corn does contribute to global warming). Teaching Tips 1. The authors describe four major periods of plant evolution. The remainder of the chapter sections on plants describes these periods as they evolved in major plant groups. This is consistent with good lecture advice: Tell them what you are going to tell them, tell them, then tell them what you told them (summarize). 2. Students might enjoy the parallel between a chicken egg and the first seeds (although this is a limited analogy). Each consists of a developing embryo, enclosed in a water-resistant packet, along with a store of food. 3. The support provided by many tightly packed mosses is analogous to the collective support of the many fibers of plush carpeting. 4. Students might wonder if humans and other animals do not also qualify as having alternation of generations. Although we do have haploid gametes, the haploid and diploid stages do not include multicellular individuals. 5. Depending upon where your course is taught, coal may be an important part of the economy. The geology of these coal deposits helps us interpret the rich history of life on Earth. If you live in a coal region, consider spending additional time on how coal was deposited, why it is an important source of energy, and how the use of fossil fuels contributes to global warming. 6. As Francois Jacob suggested, evolution works as a tinkerer and not like an engineer. New forms evolve by remodeling old forms. The structure of a flower represents the remodeling of leaves, a subject which you may want to explore in additional detail as an important lesson in evolution. 7. Floral shops frequently discard magnificent flowers that are just beyond their peak. Teachers can obtain such discards for free by contacting local floral shops and sharing your educational needs. Having a variety of flowers on hand can brighten up any discussion of angiosperms. 8. Before lecturing over the examples of angiosperm and animal cooperation, let your students try to name as many as they can. They could work in small groups or do this ahead of time and bring their responses to class (or them). 9. You might have your class spend a minute just to list all of the plant-derived materials in your classroom—cotton material, wood for pencils, paper in many forms, etc. 10. The tremendous volume of pollen released into the air is apparent to anyone suffering from allergies. You might wish to have your students find the pollen counts for your area, commonly given out in weather information. It might be interesting to track the pollen counts as you go through part of the semester. 11. Depending upon where your course it taught, you can reference any local agricultural monoculture that replaced a much more diverse native ecosystem, perhaps many years ago. From old growth forest replaced with a single fast growing species, to vast fields of corn, wheat, or soybeans that replaced native prairies, students may fail to see this loss of diversity.

Table 16.1 A Sampling of Medicines Derived from Plants

Plants and the Move onto Land

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