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Table of Contents
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Chapter 1 An Introduction to Plants and Their Study Plants Are Essential to Human Life. Plants Produce Many Medicines as well as the Food and Oxygen on Which Organisms Depend. Perspective 1.1 Coffee: Even if You Don't Know Beans Plants, Directly or Indirectly, Provide All the Food We Eat. Perspective 1.2 Breakfast at the Sanitarium: The Story of Breakfast Cereals Agriculture Provided a Secure Source of Food for Our Early Ancestors. The Plant Kingdom Is Nature's Botanical Medicine Cabinet. Clues to Possible Medicines Come from Interactions Between Plants and Animals. Perspective 1.3 Nature's Medicine Cabinet The Study of Economically Important Plants Includes Investigation of Their Ecology and Evolution. What Is a Plant? A Plant Shares Many Characteristics with Other Organisms. A Plant Is an Organism with a Set of Characteristics Unique to Itself. A Seed Develops into a Plant with Roots, Stems, and Leaves. Monocots and Dicots Have Different Kinds of Seeds. Roots Anchor Plants, Store Energy, and Absorb and Conduct Water and Minerals. The Root System Consists of Primary and Secondary Roots. Shoots Consist of Stems and Leaves. Leaves Are the Main Sites of Photosynthesis. What Is Botany? Observing and Asking Questions Are the First Steps in Studying a Problem. We All Think Like Scientists at Times. Biologists Use a Scientific Method of Investigation to Answer Questions About Life. Biotechnology Is an Active Area of Scientific Research as Well as an Industry That Will Affect Your Life. You Can Be an Informed Agent for Change. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 2 The Ecology and Natural Selection of Plants Ecology Is the Study of Interactions Between an Organism and Its Environment. The Environment of an Organism Consists of Living Organisms and Nonliving Factors. Plants Are Indicators of the Environment. Dispersal of Fruits and Seeds Reduces Seed Predation and Competition. Some Seeds and Fruits Are Dispersed by Wind and Water. Animals Disperse Many Seeds and Fruits. The Germination of a Seed and Growth of a Plant Depend on Favorable Environmental Conditions. Many Seeds Lie Dormant in a Seed Bank in the Soil. Plants Must Deal with the Environment Both Above- and Belowground. Leaves Provide an Example of an Ecological Trade-off in a Plant. Plants Maintain a Balance Between Their Root System and Shoot System. All Individuals Are Part of a Population, Which Is Part of a Community of Organisms. Plants Are the Producers of a Community. A Community and Its Abiotic Factors Constitute an Ecosystem. Plants Have Evolved with Other Organisms in Their Ecosystem. Natural Selection Determines Which Individuals Survive and Reproduce. Artificial Selection Is Controlled Mating. Perspective 2.1 Selection for Monsters Ample Evidence from Nature and the Farm Led to the Development of the Principles of Natural Selection. Natural Selection Is Meaningful Only in the Context of the Environment. Natural Selection Is a Driving Force for Evolution. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 3 Energy and Cell Chemistry What Is Energy? Perspective 3.1 Units of Energy There Are Two Types of Energy Important to Organisms: Potential Energy and Kinetic Energy. The Laws of Thermodynamics Govern the Flow of Energy in Nature. Organisms Must Obtain and Convert Energy to Survive. Metabolism Converts the Energy That Powers Life's Work. ATP Is the Main Energy Currency of Cells. Enzymes Are Required for Energy Conversions in Cells. The Molecules of Life Are Carbohydrates, Proteins, Nucleic Acids, and Lipids. The Large Organic Molecules of Life Are Polymers. Carbohydrates Store Energy and Carbon and Make Up the Wood of Trees. Cellulose and Starch Are Important Polysaccharides in Plants. Proteins Make Up Membranes, Function as Enzymes, and Store Nitrogen in Plants. Nucleic Acids-DNA and RNA-Are the Blueprints of Life. Lipids Form Membranes and Also Store Energy and Carbon in Plants. Perspective 3.2 What's Wrong with Tropical Oils? Secondary Metabolites Produced in Plants Often Have Importance to Us. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 4 Plant Cells and Tissues Plants Consist of Cells and Products of Cells. Perspective 4.1 Cell Evolution Highly Structured Organelles Have Evolved Inside Plant Cells. The Cell Membrane Is a Remarkably Changeable, Multipurpose Membrane. The Nucleus Is Surrounded by a Double-Membrane Envelope and Contains Genes That Control the Activities of the Plant Cell. The Internal Membrane System Is a Continuum of Organelles Inside the Cell. Vacuoles Help Regulate Water Content in Plant Cells and Contain Numerous Enzymes and Pigments. Ribosomes Are the Workbench of Protein Synthesis. Mitochondria and Chloroplasts Are Organelles of Energy Conversion. Perspective 4.2 Cellular Invasion: Evolution of Chloroplasts and Mitochondria The Cytoskeleton Forms a Network Within the Cell. Cell Walls Surround and Shape the Plant Cell. Membranes Regulate the Flux of Materials into and out of the Cell and Many Organelles. Proteins Control Most Membrane Functions, but the Lipid Bilayer Is Important Also. Phospholipids Form the Thin Bilayer of Membranes. Diffusion and Bulk Flow Account for Much of the Movement of Molecules in Plants. Water Potential Can Be Used to Predict the Flow of Water Through a Plant. Osmosis Is the Diffusion of Water Across a Membrane. Selectively Permeable Membranes Use Transport Proteins to Regulate the Flux of Molecules. Membranes Are Important in Cell-to-Cell Signaling in Plants. Plant Tissue Systems Help Us Understand the Evolution of Life on Land. Perspective 4.3 The Estimated Age of Eukaryotic Cells Plants Consist of Four Basic Kinds of Tissue Systems: Meristematic, Ground, Dermal, and Vascular. Meristems Are the Site of Cell Division in Plants. Ground Tissue Constitutes Most of the Primary Body of a Plant. Perspective 4.4 Hemp Dermal Tissue Forms the Epidermis That Covers the Plant Body. Vascular Tissue Is the Plant's Plumbing System. Secretory Structures Are Found in Many Plants. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 5 DNA, Genes, and Cell Division Mendel's Work Began Modern Genetics. How Does the Nucleus Control the Activities of the Cell? What Are Genes, and Why Are They Important? The Nucleus Contains DNA Associated with Proteins That Make Up the Chromosomes. The Discovery of DNA Structure Was a Major Breakthrough in Science. How Do Genes Work? RNA Is Transcribed in the Nucleus and Translated in the Cytosol. DNA Directs the Synthesis of RNA in the Nucleus. Perspective 5.1 Ribozymes and the Origin of Life All Three Types of RNA Are Required for Protein Synthesis in the Cytosol. The mRNA Is Translated in the Cytosol. The Genetic Code Is a Key to Protein Synthesis. How Is Gene Expression Regulated? Eukaryotic Chromosomes Contain Interrupted Genes. Genetic Engineering Is a Major Focus of Modern Biology. Perspective 5.2 Public Issues in Plant Genetic Engineering Perspective 5.3 An Important Little Weed How Do Plant Cells Divide? The Cell Cycle Is Completed in Cells That Divide. The Cell Cycle Involves Growth Followed by Cell Division. Perspective 5.4 The Many Uses of Plant Tissue Culture Interphase Includes G1, S, and G2 of the Cell Cycle. Mitosis and Cytokinesis Can Form New, Identical Cells as the M Phase of the Cell Cycle. How Is Cell Division Controlled? Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 6 Plant Growth and Development Plant Growth and Development Are Controlled by Many Internal and External Factors. Various Signals Regulate Plant Growth and Development. Plant Hormones Serve as Chemical Signals Between Cells and Tissue Systems. Perspective 6.1 Are Plant Hormones Like Animal Hormones? Perspective 6.2 Calcium and Cell Signaling Just How Many Groups of Plant Hormones Are There? The Environment Is Also Important in Plant Growth and Development. Perspective 6.3 Tracking the Sun Flowering Is Influenced by Genes and the Environment. Perspective 6.3 Tracking the Sun Phytochrome Is an Hourglass for Measuring Important Environmental Cues. Senescence and Dormancy Are Genetically Programmed Events in Plants. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 7 Root Systems and Plant Mineral Nutrition Roots Are a Plant's Link to the Underground Environment. Taproot Systems Have One Large Primary Root and Many Smaller Branch Roots. Fibrous Root Systems Consist of a Mass of Roots. The Root Cap Protects the Growing Parts of a Root as It Travels Through the Soil. The Subapical Region of the Root Includes the Zones of Cell Division, Cell Elongation, and Cell Maturation. The Root Consists of Layers of Different Tissues. The Rhizosphere Surrounds Each Root. Several Factors Control the Growth and Distribution of Roots. Depending on Their Environment and Age, Plants Shift Allocation of Resources to Roots or Shoots. Roots Often Possess Special Adaptations to the Environment. Epiphytes Are Adapted to Life Above the Ground. Roots Play Key Roles in the Ecology and Evolution of Plants. Mycorrhizae Are Mutualistic Relationships Between a Plant and a Fungus. Mutualistic Relationships May Evolve Between Two Organisms That Require Different Resources. Roots of Legumes Often Establish Mutualistic Relationships with Nitrogen-Fixing Bacteria. Perspective 7.1 Putting Things Back Some Root Systems Allow Plants to Affect the Ecology of an Entire Community. Many Roots Are Economically Important. Soils Are the Source of Minerals for Plants and Other Organisms in the Ecosystem. The Physical Environment of the Soil Controls Plant Growth. Plants Obtain Essential Minerals from the Soil. Essential Elements Are Required by Plants for Normal Growth and Reproduction. Most Essential Elements Have Several Functions in Plants. Deficiencies of Essential Elements Disrupt Plant Growth and Development. Some Plants Accumulate Large Amounts of Various Elements. Soils in a Rain Forest Are Deficient in Most Nutrients. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 8 Stems and Secondary Growth Stems Are Composed of the Four Kinds of Tissues Found in All Organs of a Plant. The Evolution of Taller Plants Was Aided by the Mechanical Support of Rigid Cells. Sugar Is Transported from Leaves to Roots Through Phloem in a Stem. Substances Move in the Phloem from Sources to Sinks. Investigations of Phloem Contents Have Been Aided by an Insect. Stems Play Key Roles in the Ecology of Plants. Modified Stems Adapt Plants to Different Factors in the Environment. Modified Belowground Stems Often Help Plants Survive Cold Winters. Wood Is a Secondary Tissue Produced by the Vascular Cambium. The Activity of the Vascular Cambium Is Affected by Hormones. The Environment Affects the Production of Different Kinds of Wood. Trees Have Evolved Chemical and Physical Means That Help Fend Off Infections and Pests. The Bark Is a Tree's External, Protective Barrier. Perspective 8.1 Cork Trees Can Be Killed by Girdling. Imported Wood-Boring Insects May Upset the Natural Ecology of American Forests. Secondary Growth Is Produced by Different Types of Plants and Their Parts. Wood Also Is Classified by Its Function and Location. Secondary Growth Also Occurs in Roots. Many Plants Have Unusual Secondary Growth. Typically, Monocots Do Not Have Secondary Growth. Many Stems Are Economically Important. Wood Is One of the World's Most Economically Important Plant Products. Perspective 8.2 The Bats of Summer Perspective 8.3 The Lore of Trees Different Characteristics Are Revealed in Wood Depending on How It Is Cut. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 9 Leaves and the Movement of Water The Form of Leaves Is Important to Their Function. The Arrangement of Leaves Maximizes the Absorption of Sunlight for Photosynthesis. The Two Main Types of Leaves Are Simple and Compound. A Leaf's Tissues Support Its Primary Function-Photosynthesis. The Organization of the Mesophyll Promotes Gas Exchange in the Leaf. Most Water Absorbed by a Plant's Roots Is Lost from the Shoot. The Arrangement of Cells Inside a Leaf Increases Transpiration. Several Environmental Factors Affect Transpiration. Adaptations Have Evolved That Reduce Transpiration. Deciduous Plants Drop All Their Leaves Each Year. Water Movement in a Plant Is Aided by the Form of Xylem Cells. Perspective 9.1 The Risks of Having Vessels Multicellularity and Colonization of Land Promoted Evolution of Vascular Tissue. Water Can Be Pushed Up a Plant a Short Distance by Root Pressure. Water Is Pulled Up Plants by Evaporation from Leaves. Leaves Are Affected by Environmental Factors. Plants Can Move. The Evolution of Plants Has Produced a Wide Variety of Modified Leaves. Some Carnivorous Plants Possess Modified Leaves That Contain a Community of Organisms. Many Defense Mechanisms Have Evolved Against Herbivores. Some Plants Poison Their Attackers. Plants Can Change the Lives of the Attackers. Some Plants Are Difficult for Herbivores to Digest. Many Leaves Are Economically Important. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 10 Photosynthesis Photosynthetic Organisms Are Autotrophs. What Is Light? Pigments Absorb Light, Which Drives Photosynthesis. Photosynthesis Requires Both Photochemical and Biochemical Reactions to Produce Sugars. Chloroplasts Are the Site of Photosynthesis in Plants. The Light Reactions of Photosynthesis Produce ATP. The Light Reactions of Photosynthesis Also Produce NADPH. Perspective 10.1 The Evolution of the Light Reactions The Biochemical Reactions Convert CO2 to Carbohydrates. Perspective 10.2 The Evolution of Photosynthesis: Why Aren't Plants Black? Rubisco Is Not Perfect and Fuels Carbon Loss via Photorespiration. Perspective 10.3 How Did Such a Wasteful Process as Photorespiration Evolve? C4 Photosynthesis Probably Evolved During Times of Low CO2 in the Atmosphere. Perspective 10.4 Why Don't C4 Plants Dominate the Landscape? Crassulacean Acid Metabolism (CAM) Is the Third Type of Photosynthesis Known in Nature. What Environmental Factors Affect the Rates of Photosynthesis? Perspective 10.5 Atmospheric CO2 and Photosynthesis What Happens to the Products of the Calvin Cycle? Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 11 Respiration The Two Primary Energy and Carbon Transformation Systems in Plants Are Photosynthesis and Respiration. Plants Retrieve Energy and Carbon via Respiration of Sucrose and Starch. The Energy and Carbon Economy of Most Organisms Depend on Aerobic Respiration. Cellular Respiration Forms ATP and Carbon Skeletons Used in Biosynthesis Cellular Respiration Includes Glycolysis, the Krebs Cycle, and the Electron Transport Chain. Perspective 11.1 The Potential Energy of Glucose Glycolysis Splits Glucose, Producing Some ATP. The Krebs Cycle Is Fueled by Pyruvate and Forms Some ATP. Perspective 11.2 Models and Respiration ATP Is Formed as Electrons Flow Through the Electron Transport Chain to Oxygen. ATP Synthesis Is Driven by Electron Flow That Generates a Proton Gradient. Perspective 11.3 Botany and Politics Fermentation Can Occur When O2 Levels Are Low. Cyanide-Resistant Respiration Is Important in Some Plants. Perspective 11.4 How Does Skunk Cabbage Get So Hot? Lipids Are Respired in Germinating Seeds. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 12 Flowers and Fruits Flowers Are the Reproductive Organs of Flowering Plants. Stamens Produce Pollen Grains. Pistils Contain at Least One Ovule in Their Ovary. Petals Are the Colorful, Fragrant Parts of a Flower. Leaflike Sepals Protect the Immature Flower. How Did Angiosperms Evolve? Flower Parts Probably Evolved from Leaves. The Fossil Record Provides Clues About the Evolution of Flowering Plants. Flowering Plants Produce an Embryo and Endosperm Inside a Seed. Gametes Are Haploid, Reproductive Cells. Double Fertilization Involves the Fusion of Sperm with Different Cells in the Ovule. Reproductive Morphology Helps Explain the Diversity of Flowering Plants. Some Flowers Lack Sepals, Petals, Stamens, or Pistils. Monocots and Dicots Can Be Identified by the Number of Their Floral Parts. Groups of Flowers Comprise an Inflorescence. Plant Reproductive Morphology Promotes Outcrossing and Hybrid Vigor. Ecological Trade-offs Occur in the Reproduction of Flowering Plants. Plants Produce Clones Through Vegetative Reproduction. Floras Help Identify and Describe the Ecology of Flowering Plant Species of a Region. Pollination of a Flowering Plant by an Animal Is an Example of Co-evolution. Pollination by Wind Is Common; Pollination by Water Is Rare. Insects Pollinate Brightly Colored, Fragrant Flowers. Perspective 12.1 Orchids That Look Like Wasps Some Bats and Birds Pollinate Large Flowers. A Fruit Develops from the Ovary of a Flower. Types of Fruit Can Be Identified Using a Dichotomous Key. Hormones Promote Fruit Development. The Economic Value of Flowers and Flowering Plants Is Enormous. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 13 Genetics Gregor Mendel's Landmark Work Led to the Theory of Inheritance. Perspective 13.1 Artificial Hybridization in Plants Genotypes Are Genes, and Phenotypes Are Traits. Mendel Also Studied Multiple Traits. Meiosis Separates Mendel's "Heritable Factors" During Gamete Formation. DNA Was Shown to Be the Hereditary Material. Genes Are Made of DNA and Form the Units of Inheritance Described by Mendel. Several Forms of Complex Inheritance Have Been Discovered. There Are Three Types of Dominance: Complete, Incomplete, and Codominance. Perspective 13.2 Examining Proteins by Gel Electrophoresis There Can Be Multiple Alleles of the Same Gene. Multiple Genes Are Common in Plants. Non-Mendelian Inheritance May Not Produce Mendelian Ratios. Linked Genes Are Inherited Simultaneously. Cytoplasmic Genes Are Inherited Independently of Sexual Reproduction. Mutations Are Inheritable Changes in Genes. Transposable Elements Are Mobile Pieces of DNA. Sexual Reproduction Provides Variation in Plants. Meiosis Produces Haploid Spores That Become Gametes. Pollination and Fertilization Bring Gametes Together in Sexual Reproduction. Meiosis Involves Two Nuclear Divisions That Later Provide Genetic Variation in Offspring. Perspective 13.3 Polyploidy in Plants Genetic Recombination Can Occur Without Crossing-over. Why Sex in Plants? Sexual Reproduction Results in Variation Among Members of a Population. Asexual Reproduction Produces Clones with Uniform Genetic Information. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 14 Evolution Studies of the Natural History of Organisms Contributed to the Theory of Evolution. Charles Darwin's Work Laid the Foundation for the Modern Theory of Evolution. Charles Darwin Was a Natural Historian. Darwin and Wallace Individually Formulated a Theory of Natural Selection. Investigations Since Darwin's On the Origin of Species Provide Extensive Evidence for Descent with Modification. Ample Evidence Indicates the Earth Is over 4 Billion Years Old. Vascular Plants Have Left Fossil Evidence About Their Evolution. Homologous Structures Are Derived from a Common Ancestor. Convergent Characteristics Occur in Unrelated Organisms Living in Similar Habitats. Biogeography Also Provides Evidence for Evolution. Biologists Now Use Molecular Evidence to Study the Evolution of Organisms. Evolution Can Sometimes Be Observed. Natural Selection and Evolution Are Not the Same Thing. There Are Three Basic Kinds of Natural Selection: Stabilizing, Directional, and Diversifying Selection. Genetic Variation Is Necessary for Natural Selection. The Genes of an Organism Are Part of the Gene Pool. Perspective 14.1 Darwin's Big Mistake Genetic Variation Is Promoted by Gene Flow from One Population to Another. The Genetic Variation of Small Populations May Be Affected by Genetic Drift. Sexual Reproduction Maintains Genetic Variation in a Population. The Study of Evolution Keeps Growing. Many Evolutionary Studies Are Economically Important. Perspective 14.2 Unstoppable Killers Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 15 The Diversity and Classification of Plants We Organize Plants into Groups Using Many Different Criteria. What Is a Species? Taxonomists Often Identify Species Based on the Morphology of the Organisms. Biological Species Are Defined by Their Inability to Reproduce with Other Species. Biologists Disagree How New Species Are Formed. Physical and Biological Barriers Can Reproductively Isolate Populations from Each Other. Speciation Requires a Population to Diverge from Its Parent Population. Geographic Isolation Can Lead to New Species. Species May Arise Even When Populations Are Not Geographically Isolated. Plants Frequently Possess Multiple Sets of Chromosomes, Which Can Lead to Speciation. Perspective 15.1 Polyploids in the Kitchen A Species May Show Ecological Variation over Its Range. Ecological Variation May Be the First Step Toward the Formation of New Species. Classification Is a Continuously Changing Process. Linnaeus Developed a System of Binomial Nomenclature That We Still Use Today. Perspective 15.2 Is It Time to Change the System? Perspective 15.3 How to Name a New Plant Species Modern Classification Systems Are Based on Evolutionary Relationships. Classification Systems Emphasize Ancestral Versus Derived Characteristics. Scientists Disagree About Which System of Classification Is the Best. New Investigative Approaches Help Systematists Study Phylogenetic Relationships. A Goal of Cladistics Is to Improve Classification Schemes. Similar Organisms Are Grouped Together in Successively Higher Categories. A Modern System of Classification Identifies Three Domains. Many Systematic Studies Are Economically Important. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 16 Bacteria, Fungi, and Algae Bacteria Are the Most Abundant Organisms on Earth. Bacteria Are Prokaryotes. Bacteria Are More Diverse Metabolically Than Eukaryotes. The Generalized Life Cycle of Bacteria Is Simpler Than in Plants. The Classification of Bacteria Has Recently Changed. Bacterialike Cells Were Probably the First Living Organisms. Chloroxybacteria Provide Evidence for the Evolution of Chloroplasts. Cyanobacteria Were Once Called Blue-Green Algae Because They Resemble Algae and Are Photosynthetic. Bacteria Affect Every Aspect of Our Lives. Perspective 16.1 Deadly Food! Beware! Fungi Are Nonphotosynthetic Eukaryotes with Diverse Roles in Ecosystems. Like Bacteria, Fungi Grow Just About Everywhere. Perspective 16.2 Disappearing Fungi Fungi Are Traditionally Classified into Four Main Groups: Zygomycetes, Ascomycetes, Basidiocycetes, and Deuteromycetes. Lichens Are Fungi and Other Organisms Living Together. Some Fungi Are Important to Plant Growth. Fungi Have Considerable Economic Importance. Algae Include Some of the Smallest and Largest Photosynthetic Eukaryotes. Green Algae Are the Ancestors of Plants. Most Brown Algae Are Large Marine Organisms. Red Algae Are Also Mostly Marine Organisms. Diatoms Are Important in Ocean Ecosystems. There Are Other Divisions of Algae with Ecological Importance. The Fossil History of Algae Provides Insight into Their Origins. Algae Are Important in Many Ecosystems. Algae Have Widespread Economic Importance. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 17 Bryophytes and Ferns: The Seedless Plants Plants Evolved from Aquatic to Terrestrial Ecosystems. Bryophytes Are Small, Seedless, Nonvascular Plants. The Life Cycle of Bryophytes Involves Dominant Gametophytes and Small Sporophytes. There Are Three Major Groups of Bryophytes: Mosses, Liverworts, and Hornworts. Mosses Are the Largest and Most Familiar Group of Bryophytes. Liverworts Are Low-Growing Plants Usually Found in Wetlands. Hornworts Are the Smallest Group of Bryophytes. Bryophytes Grow in Many Different Habitats. Perspective 17.1 Secrets of the Bog The Fossil Record of Bryophytes Is Poor and Shows Relatively Little Diversity. Bryophytes Today Have Limited Economic Importance. Ferns and Related Plants Are Seedless Vascular Plants. Seedless Vascular Plants Have Alternation of Generations with Dominant Sporophytes. Xylem and Phloem Tissues Provide Vascular Plants with a Selective Advantage on Land. There Are Four Groups of Seedless Vascular Plants: Whisk Ferns, Club Mosses, Horsetails, and Ferns. Seedless Vascular Plants Interact with Other Organisms. Seedless Vascular Plants of Today Have Limited Economic Importance. Fossils of Vascular Plants Are Much More Abundant Than Those of Bryophytes. Perspective 17.2 How Does a Plant Become a Fossil? Coal-Age Trees Were Giant Club Mosses, Giant Horsetails, and Tree Ferns. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 18 Gymnosperms and Angiosperms: The Seed Plants Gymnosperms and Angiosperms Have Evolved Characteristics That Allow Them to DominateLife on Land. Gymnosperms Produce Naked Seeds. Gymnosperms Produce Both Male and Female Gametophytes. Many Gymnosperms Produce Seeds and Pollenin Cones. The Pollen Grain of a Gymnosperm Is a Reduced Male Gametophyte. Compared to Angiosperms, Few Gymnosperms Live in the World Today. Maidenhair Trees Are Native to China but Are Cultivated Around the World. Cycads Are Tropical Gymnosperms. Conifers Produce Seeds in Woody Cones. The Most Unusual Gymnosperms Are Gnetophytes. Many Gymnosperms Are Adapted to Temperate Climates. Gymnosperms Have Many Economically Important Industrial Uses. Perspective 18.1 A Fungus That May Save the Yews Perspective 18.2 How Much Paper Do We Use? Flowering Plants Are the Most Diverse Plant Group. Could Dinosaurs Be Responsible for the Diversity of Flowering Plants Today? The Life Cycle of Flowering Plants Is Different from That of All Other Plants. Flowering Plants Are Economically, Culturally, and Historically Important to Humans. Cereals Feed the Human Population. The Struggle to Produce Enough Food in the World Continues. There Are Promising Prospects for the Future Beyond the Green Revolution. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Chapter 19 Ecology Ecologists Study the Flow of Energy Through an Ecosystem. Energy Is Lost from an Ecosystem As Heat. Each Ecosystem Can Support Only a Limited Number of Organisms. Highly Productive Ecosystems Often Have a High Diversity of Species. Nutrients Cycle Through an Ecosystem. Microorganisms Play Critical Roles in the Nitrogen Cycle. Photosynthesis and Respiration Are Key Processes in the Carbon Cycle. Perspective 19.1 Curbing Methane Emissions to Curtail the Greenhouse Effect The Atoms That Make a Plant's Body Have Cycled Through Other Organisms. Ecosystems Change Through Time. Primary Succession May Be Initiated in Water. Secondary Succession Happens After Human and Other Disturbances. Biomes Are Large Ecosystems Dominated by Particular Groups of Plants. The Tundra Is the Treeless Plain. Taiga, Found South of the Tundra, Is Dominated by Conifers. Temperate Deciduous Forests Grow in Many Parts of the Eastern Half of the United States. Perspective 19.2 Making Maple Syrup Grasslands Once Supported Huge Populations of Herbivores. Many Plants Adapted to the Dry Climates of Desert Biomes Store Water. Perspective 19.3 Desertification: What Is It, and What Causes It? The Chaparral Frequently Burns. Tropical Rain Forests Are Storehouses of Species Diversity. Humans Drastically Affect the Ecosystem in Which They Live. Acid Rain Contributes to the Degradation of Forests. The Thinning Ozone Layer Allows More Ultraviolet Light to Strike the Earth. Humans Help Pests Invade New Territories. The Future of the Tropical Rain Forest Biome Is Threatened. Summary Writing to Learn Botany Thought Questions Suggested Readings On the Internet Appendices A What Is Genetic Engineering? B Fundamentals of Chemistry for Botany Students 
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