Sterns Introductory plant biology.pdf

- W' Stern’s Introductory Plant , Biology i \'' ^ i1 f / ^^Twelfth f...

- W' Stern’s Introductory Plant , Biology i \'' ^ i1 f / ^^Twelfth f i -'Twelfth Edition ' af, E This INTERNATIONAL ^ James E. Bidlack STUDENT EDITION is not Shelley H. Jansky to be soid or purchased in North America and contains content that is different from its North £ , American version. ' ' > r McGRAW-HILL INT ATIONAL EDITION 0  Edition Twelve STERN'S INTRODUCTORY PLANT BIOLOGY James E. Bidlack University of Central Oklahoma Shelley H. Jansky University of Wisconsin ~ Madison Connect i Learn I Succeed ” Contents in Brief ' About the Authors x Preface xii 1 What Is Plant Biology? 1 2 The Nature of Life 13 3 Cells 29 4 Tissues 53 5 Roots and Soils 64 6 Stems 84 7 Leaves 103 8 Flowers, Fruits, and Seeds 124 9 Water in Plants 146 10 Plant Metabolism 162 11 Growth 189 12 Meiosis and Alternation of Generations 213 13 Genetics 222 14 Plant Breeding and Propagation 245 15 Evolution 265 16 Plant Names and Classification 280 17 Domain (Kingdom) Bacteria, Domain (Kingdom) Archaea, and Viruses 294 18 Kingdom Protista 318 19 Kingdom Fungi 348 20 Introduction to the Plant Kingdom; Bryophytes 373 21 The Seedless Vascular Plants: Ferns and Their Relatives 388 22 Introduction to Seed Plants: Gymnosperms 413 23 Seed Plants: Angiosperms 432 24 Flowering Plants and Civilization 452 25 Ecology 478 26 Biomes 503 Appendix 1 Scientific Names of Organisms Mentioned in the Text 515 Appendix 2 Biological Controls 534 Appendix 3 Useful and Poisonous Plants, Fungi, and Algae 541 Appendix 4 House Plants and Home Gardening 566 Appendix 5 Metric Equivalents and Conversion Tables 590 Glossary 592 Photo Credits 605 Index 607 About the Authors x Preface xii Tissues 53 Chapter Outline 53 1 What Is Plant Biology? 1 Overview 54 Some Learning Goals 54 Chapter Outline 1 Meristematic Tissues 54 Overview 2 Tissues Produced by Meristems 55 Some Learning Goals 2 Summary 62 The Relationship of Humans to Their Review Questions 63 Environment 4 Discussion Questions 63 Additional Reading 63 Botany as a Science 7 Diversification of Plant Study 8 Plant Sciences Inquiry: Plant Biology Roots and Soils 64 and the Internet 10 Chapter Outline 64 Summary 10 Overview 65 Review Questions 12 Some Learning Goals 65 Discussion Questions 12 How Roots Develop 65 Additional Reading 12 Root Structure 66 Specialized Roots 70 2 The Nature of Life 13 Mycorrhizae 74 Chapter Outline 13 Root Nodules 76 Overview 14 Human Relevance of Roots 76 Some Learning Goals 14 Soils 77 Attributes of Living Organisms 14 Plant Sciences Inquiry: Metal-Munching Chemical and Physical Bases of Life 15 Plants 80 Summary 27 Summary 81 Review Questions 28 Review Questions 82 Discussion Questions 28 Discussion Questions 82 Additional Reading 28 Additional Reading 82 3 Cells 29 Stems 84 Chapter Outline 29 Chapter Outline 84 Overview 30 Overview 85 Some Learning Goals 30 Some Learning Goals 85 Cells 30 External Form of a Woody Twig 85 Eukaryotic versus Prokaryotic Cells 33 Origin and Development of Stems 86 Cell Structure and Communication 33 Plant Sciences Inquiry: Standing in Fields of Stone 87 Cellular Components 36 Cellular Reproduction 44 Tissue Patterns in Stems 89 Plant Sciences Inquiry: Microscapes 48 Specialized Stems 95 Wood and Its Uses 97 Higher Plant Cells versus Animal Cells 50 Summary 101 Summary 51 Review Questions 102 Review Questions 52 Discussion Questions 102 Discussion Questions 52 Additional Reading 102 Additional Reading 52  Contents Phylum Hepaticophyta—Liverworts 376 Kingdom Protista 318 Phylum Anthocerophyta—Hornworts 380 Chapter Outline 318 Phylum Bryophyta—Mosses 380 Overview 319 Plant Sciences Inquiry: Flibernating Mosses 384 Some Learning Goals 319 Features of Kingdom Protista 319 Human and Ecological Relevance Algae 320 of Bryophytes 385 Summary 385 Phylum Chlorophyta—The Green Algae 320 Review Questions 386 Phylum Chromophyta—The Yellow-Green Discussion Questions 386 Algae, Golden-Brown Algae, Diatoms, Additional Reading 386 and Brown Algae 327 Phylum Rhodophyta—The Red Algae 332 Phylum Euglenophyta—The Euglenoids 335 The Seedless Vascular Plants: Phylum Dinophyta—The Dinoflagellates 336 Ferns and Their Relatives 388 Phylum Cryptophyta—The Cryptomonads 336 Phylum Prymnesiophyta (Haptophyta)—The Chapter Outline 388 Haptophytes 337 Overview 389 Phylum Charophyta—The Stoneworts 337 Some Learning Goals 389 Human and Ecological Relevance Phylum Psilotophyta—The Whisk Ferns 389 of the Algae 338 Phylum Lycophyta—The Ground Pines, Other Members of Kingdom Protista 341 Spike Mosses, and Quillworts 391 Phylum Myxomycota—The Plasmodial Slime Phylum Equisetophyta—The Horsetails Molds 342 and Scouring Rushes 397 Phylum Dictyosteliomycota—The Cellular Phylum Polypodiophyta—The Ferns 401 Slime Molds 344 Fossils 408 Phylum Oomycota—The Water Molds 344 Summary 410 Summary 346 Review Questions 411 Review Questions 347 Discussion Questions 411 Discussion Questions 347 Additional Reading 411 Additional Reading 347 Introduction to Seed Plants: Kingdom Fungi 348 Gymnosperms 413 Chapter Outline 348 Chapter Outline 413 Overview 349 Overview 414 Some Learning Goals 349 Some Learning Goals 414 Distinctions between Kingdoms Protista Phylum Pinophyta—The Conifers 415 and Fungi 349 Other Gymnosperms 420 Kingdom Fungi—The True Fungi 350 Human Relevance of Gymnosperms 423 Lichens 368 Plant Sciences Inquiry: A Living Fossil? 428 Summary 371 Summary 429 Review Questions 372 Review Questions 430 Discussion Questions 372 Discussion Questions 431 Additional Reading 372 Additional Reading 431 Introduction to the Plant Kingdom: Seed Plants: Angiosperms 432 Bryophytes 373 Chapter Outline 432 ' ^ Chapter Outline 373 Overview 433 Overview 374 Some Learning Goals 433 Some Learning Goals 374 Phylum Magnoliophyta—The Flowering Introduction to the Bryophytes 374 Plants 434  Contents IX Plant Sciences Inquiry: The Difference Aquifer Depletion 496 Between "n" and "x" in Plant Life Cycles 440 Loss of Biodiversity 496 Pollination Ecology 442 Restoration of the Land 498 Herbaria and Plant Preservation 445 Plant Sciences Inquiry: John Muir, Father Summary 450 of America's National Park System 499 Review Questions 450 Summary 500 Discussion Questions 451 Review Questions 501 Additional Reading 451 Discussion Questions 501 Additional Reading 501 Flowering Plants and Civilization 452 26 Biomes 503 Chapter Outline 452 Chapter Outline 503 Overview 453 Overview 504 Some Learning Goals 453 Learning Goal 504 Origin of Cultivated Plants 453 Major Biomes of North America 504 Selected Families of Flowering Plants 455 Plant Sciences Inquiry: Photosynthesis, Global Dicots (Now Recognized in Two Warming, and Tropical Rain Forests 512 Groups) 456 Summary 513 Monocots 471 Review Questions 513 Plant Sciences Inquiry: Coffee Discussion Questions 514 and Caffeine 474 Additional Reading 514 Summary 476 Review Questions 477 Appendix 1 Scientific Names of Organisms Discussion Questions 477 Mentioned in the Text 515 Additional Reading 477 Appendix 2 Biological Controls 534 Appendix 3 Useful and Poisonous Ecology 478 Plants, Fungi, and Algae 541 Chapter Outline 478 Appendix 4 House Plants and Home Overview 479 Gardening 566 Some Learning Goals 479 Appendix 5 Metric Equivalents and Plants and the Environment 479 Conversion Tables 590 Life Histories 484 Natural Cycles 485 Succession 488 Glossary 592 The Impact of Humans on Plant Photo Credits 605 Communities 493 Global Warming 493 Index 607 Erosion 495 About the Authors Jim Bidlack, Kingsley Stern, and Shelley Jansky at Kingsley's office residence in Paradise, California. In late 1999/early 2000, Kingsley Stern and McGraw-Hill of these individuals. Dr. Stern handpicked two botanists. Publishers initiated a search to find scientists to join the Dr. Jim Bidlack and Dr. Shelley Jansky, to work with him. author team for Stern’s Introductory Plant Biology. After Over the years, the team corresponded directly through nearly three decades of publishing this successful textbook, personal meetings, dozens of phone calls, and hundreds of it was clear to Dr. Stern and the people at McGraw-Hill that e-mails, to improve upon and update content in the book. new botanists would help to further enrich the content and Upon completion of the eleventh edition. Dr. Stern passed continue the dedication and hard work needed for future away, leaving his work to the remaining authors, who editions. Many professors using the text came to mind but continue to expand upon, revise, and update the legacy of several, in particular, had expressed the desire, knowledge, Stern’s Introductory Plant Biology in this twelfth and sub¬ and enthusiasm to become successful authors. After review sequent editions.  About the Authors XI James E. Bidlack Shelley H. Jansky Jim Bidlack received a B.S. Degree in Agronomy, with a Shelley H. Jansky received a Bachelor’s Degree in Biology Soil & Crop Option, from Purdue University in 1984 and from the University of Wisconsin-Stevens Point in 1982, continued his education with a Master’s Degree in Crop and M.S. and Ph.D. degrees in Plant Breeding and Plant Physiology at the University of Arkansas in 1986. Upon com¬ Genetics from the University of Wisconsin-Madison in pleting a Ph.D. in Plant Physiology at Iowa State University 1984 and 1986, respectively. Her graduate work focused on in 1990, Jim joined the teaching faculty at the University developing methods to incorporate genes from wild rela¬ of Central Oklahoma (UCO) where he is a Professor of tives of potato into the cultivated potato. Then, she spent Biology. His first paper was published from undergraduate four years as an Assistant Professor at North Dakota State research at Purdue University on the use of synthetic growth University, teaching courses in plant breeding and plant regulators to stimulate seed germination. Subsequent work propagation, and performing research in the potato breeding at Arkansas, Iowa, and Oklahoma focused on soybean phys¬ program. She taught courses in botany, genetics, and horti¬ iology, cell wall chemistry, and alternative crops, as well as culture, and continued to perform potato genetics research at teaching responsibilities in plant biology. Equipment and the University of Wisconsin-Stevens Point from 1990 until student salaries for Jim’s research projects have been funded 2004. She was the chair of the Department of Biology and by grants from the National Science Foundation (NSF) and was promoted to Associate Professor in 1992 and Professor the United States Department of Agriculture (USDA). About in 1995. In 2004, she accepted a position as a Research a dozen refereed publications, as well as 40 abstracts and Geneticist with the U.S. Department of Agriculture and popular articles, have resulted from this work. Jim has been an assistant professor in the Department of Horticulture at recognized with UCO’s Presidential Partner’s Excellence the University of Wisconsin-Madison. Her potato research in Teaching Award; University Merit Awards in Service, program focuses on the utilization of disease resistance and Research, and Teaching; the Biology Club Teaching Award; nutritional quality genes from wild potato relatives for the and the Pre-Med Teaching Award. Some of Jim’s additional improvement of cultivated potato varieties. She received responsibilities have included participation on NSF and the University of Wisconsin-Stevens Point Excellence in USDA Review Panels, membership on the National Biology Teaching Award in 1992 and the University Scholar Award Editorial Board for the Multimedia Educational Resource in 2000. She has published 46 refereed research articles and for Learning and Online Teaching (MERLOT) Project, and four book chapters. Executive Directorship of the Metabolism Foundation. Plants and algae are essential for life on earth as it exists classification; Chapters 17 through 23 stress, in phylogenetic today. They provide our world with oxygen and food, con¬ sequence, the diversity of organisms traditionally regarded tribute an essential part of water and nutrient cycling in eco¬ as plants; and Chapter 24 deals with ethnobotanical aspects systems, provide clothing and shelter, and add beauty to our and other information of general interest pertaining to environment. Some scientists believe that if photosynthetic 16 major plant families or groups of families. Chapters 25 and organisms exist on planets beyond our solar system, it could 26 present an overview of the vast topic of ecology, although be possible to sustain other forms of life that depend upon ecological topics and applied botany are included in the pre¬ them to survive. ceding chapters as well. Some of these topics are broached in Botany today plays a special role in many interests of anecdotes that introduce the chapters, while others are men¬ both major and nonmajor students. For example, in this tioned in the ecological review summaries, in the human and text, topics such as global warming, ozone layer depletion, ecological review sections, and in the extensive appendices. acid rain, genetic engineering, organic gardening. Native American and pioneer uses of plants, pollution and recy¬ cling, house plants, backyard vegetable gardening, natural dye plants, poisonous and hallucinogenic plants, nutritional LEARNING AIDS values of edible plants, and many other topics are discussed. To intelligently pursue such topics, one needs to understand A chapter outline, review questions, discussion questions, how plants are constructed, and how they function. To this and additional reading lists are provided for each chapter. end, the text assumes little prior knowledge of the sciences New terms are defined as they are introduced, and those that on the part of the student, but covers basic botany, without are boldfaced are included, with their pronunciation, in a excessively resorting to technical terms. The coverage, glossary. A list of the scientific names of all organisms men¬ however, includes sufficient depth to prepare students to go tioned throughout the text is given in Appendix 1. Appendix 2 further in the field, should they choose to do so. deals with biological controls and companion planting. The text is arranged so that certain sections can be Appendix 3 includes wild edible plants, poisonous plants, omitted in shorter courses. Such sections may include topics medicinal plants, hallucinogenic plants, spices, tropical such as soils, molecular genetics, and phylum Bryophyta. fruits, and natural dye plants. Appendix 4 gives horticultural Because botany instructors vary greatly in their opinions information on house plants, along with brief discussions on about the depth of coverage needed for photosynthesis and how to cultivate vegetables. Nutritional values of the veg¬ respiration in an introductory botany course open to both etables are included. Appendix 5 covers metric equivalents majors and nonmajors, these topics are presented at three and conversion tables. different levels. Some instructors will find one or two levels sufficient, whereas others will want to include all three. Both majors in botany and nonmajors who may initially be disinterested in the subject matter of a required course fre¬ NEW TO THIS EDITION quently become engrossed if the material is related repeatedly The twelfth edition has retained the hallmark style and peda¬ to their popular interests. This is reflected, as intimated above, gogy that have made it one of the most enduring and popular in the considerable amount of ecology and ethnobotany introductory plant biology books on the market. At the same included with traditional botany throughout the book. time, this edition has undergone many changes to expand upon, revise, and update topics in plant biology. Most of the chapters include new opening photographs, revisions as sug¬ gested by reviewers, and updated additional readings. Many ORGANIZATION OF THE TEXT new photographs have replaced some of the older pictures or have been added within individual chapters. Some of the A relatively conventional sequence of botanical subjects is fol¬ more interesting components that make this twelfth edition lowed. Chapters 1 and 2 cover introductory and background more accurate and up-to-date with our current understand¬ information; Chapters 3 through 11 deal with structure and ing of plant biology include the following: function; Chapters 12 and 13 introduce meiosis and genet¬ Chapter 1 (What Is Plant Biology?): Several new ics. Chapter 14 discusses plant propagation and biotechnol¬ images have been added, including a new picture of residue ogy; Chapter 15 introduces evolution; Chapter 16 deals with floating on the water as an example of pollution as well as a xii  Preface XIII more typical picture of a tropical rain forest in Costa Rica. Chapter 14 (Plant Breeding and Propagation): The text New text has been added on the use of ethanol in vehicles and figure on making transgenic plants have been revised to and the sources of ethanol, such as corn, switchgrass, and improve the accuracy of the chapter. wood chips. Chapter 15 (Evolution): A new section called “An Chapter 2 (The Nature of Life); The chapter has been Introduction to Evolution” has been added to include topics revised to provide a more detailed explanation about how such as evolutionary agriculture, evolutionary medicine, genetic makeup and environment affect the growth of species extinction and invasion, and biotechnology and plants. evolution. Additional information has also been added to Chapter 3 (Cells): An improved introductory statement present the three revolutions of evolutionary thought as well has been provided to explain how plant cells are composed as a discussion of macroevolution. Two new photos have of cell walls and membrane-bound organelles. In addition, been added to accompany these topics. the information for adjacent cells has been revised to show Chapter 16 (Plant Names and Classification): A new location of ribosomes and dictyosomes, as well as a more section titled “The Species Concept” has been added to accurate explanation of plasmodesmata. present the morphological, interbreeding, ecological, cladis- Chapter 4 (Tissues): Revisions for this chapter include a tic, eclectic, and nominalistic components of speciation. new ecological review on chimeras, with examples of varia¬ Chapter 17 (Domain (Kingdom) Bacteria, Domain tions in leaf color and thornless blackberries. (Kingdom) Archaea, and Viruses): New information on Chapter 5 (Roots and Soils): To make the chapter tuberculosis and on E. coli strain 0157:H7 (accompanied by content more accessible, the images and diagrams in this a picture) has been added to show how certain bacteria can chapter have been rearranged so that their descriptions are cause problems in human populations. A new photograph of closer to the actual figures. bacteria growing in hot springs has also been added to the Chapter 6 (Stems): A new photograph showing false chapter. tree rings has been added, along with an ecological review Chapter 18 (Kingdom Protista): New photographs, to explain dendroclimatology and how tree rings are including a living diatom, a giant kelp showing air bladders, studied to provide a temporal record of environmental and a diatomaceous earth quarry, have been added to the conditions. chapter. Chapter 7 (Leaves): New text has been added to Chapter 19 (Kingdom Eungi): Up-to-date photographs describe evolution and variation in leaf morphology. The have been added of a morel, ergotized barley, and a fly aga¬ chapter also includes a new photograph on autumnal colors ric mushroom. New text has also been added on the topic of of leaves. chytridiomycosis. Chapter 8 (Flowers, Fruits, and Seeds): New text has Chapter 20 (Introduction to the Plant Kingdom: been added on seed dispersal, along with an emphasis on the Bryophytes): Photographs of a female gametophyte and a evolutionary trends in dispersal mechanisms. leafy liverwort have been replaced to more clearly show Chapter 9 (Water in Plants): A new photographic image structures described in the text, and an inset of a moss sporo- to illustrate the action of diffusion from incense has been cyte has been added to the moss life cycle. added. In addition, a definition and description of hydropon¬ Chapter 21 (The Seedless Vascular Plants: Perns and ics is now included in the chapter. Their Relatives): A picture of a Lycopodium gametophyte Chapter 10 (Plant Metabolism): A new, more detailed has been added and the photo of a branched horsetail has diagram of the Calvin cycle has been provided to show been replaced to show more clarity and detail. Text on the greater detail of the reactions that take place in the light- life cycle of a fern has been modified to explain develop¬ independent reactions. ment of the sporophyte generation. Chapter 11 (Growth): Learning goals have been revised Chapter 22 (Introduction to Seed Plants: Gymnosperms): to more accurately represent what is described in the chap¬ More detailed pictures, of a facicle of pine needles and of ter. New text has been added to provide a modern explana¬ a female cycad, have been added. The life cycle of a pine tion of how mRNA is involved in stimulation of flowering. has been modified to show additional structures after A new picture of a pineapple field has been added as an fertilization. example of how temperature can be used to predict the best Chapter 23 (Seed Plants: Angiosperms): A new Plant time for harvest of some crops. Sciences Inquiry Box has been added to explain the differ¬ Chapter 12 (Meiosis and Alternation of Generations): ence between “n” and “x” in plant life cycles. Incorporation New terminology has been introduced in this chapter to of “n” and “x” terminology is now woven throughout this distinguish between use of “n” and “x” for alternation of chapter and others. New pictures of carrion flower and hum¬ generations and ploidy number, respectively. mingbird pollination have also been added. Chapter 13 (Genetics): New text has been added to Chapter 24 (Plowering Plants and Civilization): This describe transposable elements and how certain transposons chapter features a new photograph showing more detail of might allow plants to tolerate stress. A discussion of the a poppy capsule. Text has also been added to provide more United States Plant Genome Initiative has also been inte¬ up-to-date statistics for tobacco, tomato, and potato produc¬ grated into the chapter. tion in the United States and the world. XIV Preface Chapter 25 (Ecology): This chapter has been signifi¬ Frances Rundlett, Georgia State University cantly revised and updated to include new photographs as Neil Sawyer, University of Wisconsin-Whitewater well as discussions of communities; the effect of soil min¬ Staria Vanderpool, Arkansas State University eral content on plant species distribution; trophic efficiency; Carol Wake, South Dakota State University allelopathy; life histories; the water, carbon, and nitrogen Ami Lea Wangeline, Colorado State University cycles; succession, using Mount St. Helens as an example; Justin Williams, Sam Houston State University climate change and its potential implications; wind, water, Kathleen Wood, University of Mary Hardin-Baylor and soil erosion; land reclamation; loss of biodiversity; acid Upon reaching this milestone twelfth edition, we would also rain; wetlands; species invasions; and land restoration. like to once again extend gratitude to the reviewers of earlier Chapter 26 (Biomes): An updated photo with a better editions, who have provided considerable comments and depiction of a prairie setting with little bluestem has been suggestions. Although too numerous to include here, their incorporated into the chapter. contributions have been much appreciated. The following is a list of reviewers for the past few editions: Ligia Arango, Stone Child College ACKNOWLEDGMENTS Joseph Arditti, University of California-Irvine Mark H. Armitage, Azusa Pacific University Over 200 reviewers for the past few editions, along with more Janice Asel, Mitchell Community College than 20 reviewers for this twelfth edition, have helped to revise Tasneem K. Ashraf, Cochise College-Sierra Vista and update Stem’s Introductory Plant Biology. In particular, Ralph A. Backhaus, Arizona State University Roger del Moral, who has been a respected reviewer of this Nina L. Baghai-Riding, Delta State University book, rewrote and added many new sections for Chapter 25 Randy G. Balice, New Mexico Highlands University on Ecology. Others who have read parts of the manuscripts of Susan C. Barber, Oklahoma City University various editions and made many helpful suggestions in the past Paul W. Barnes, Southwest Texas State University include Richard S. Demaree, Jr., Patricia Edelmann, Robert I. Sharon Bartholomew-Began, West Chester University Ediger, Lany Hanne, Donald T. Kowalski, Robert B. McNaim, Robert W. Bauman, Jr., Amarillo College and Robert Schlising. Additional appreciated encouragement and Dorothea Bedigian, Washington University contributions were made by Isabella A. Abbott, Donald E. Brink, Patricia Bedinger, Colorado State University Jr., Gerald Carr, William F. Derr, Timothy Devine, Beverly Maria Begonia, Jackson State University Marcum, Robert McNulty, Paul C. Silva, Lorraine Wiley, the Robert A. Bell, University of Wisconsin-Stevens Point faculty and staff of the Department of Biological Sciences, Cynthia A. Bottrell, Scott Community College California State University, Chico, colleagues at the University Richard R. Bounds, Mount Olive College of Central Oklahoma, and the Lyon Arboretum of the University Richard G. Bowmer, Idaho State University of Hawaii, as well as the editorial, production, and design staffs Rebecca D. Bray, Old Dominion University of McGraw-Hill Pubhshers. James A. Brenneman, University of Evansville The authors extend thanks to the following reviewers George M. Briggs, State University of New York who provided recent feedback on the text and the illustra¬ Michelle Briggs, Lycoming College tions. Their help has been invaluable in shaping the twelfth George M. Brooks, Ohio Unviersity edition of Stem’s Introductory Plant Biology. These review¬ Suzanne Butler, Miami-Dade College ers include the following: William J. Campbell, Louisiana Technical University Suzanne Butler, Miami Dade College Ajoy G. Chakrabarti, South Carolina State University William Cook, Midwestern State University Brad S. Chandler, Palo Alto College Kenneth Curry, University of Southern Mississippi Gregory Chandler, University of North Carolina- Cynthia Dassler, Ohio State University Wilmington Roger del Moral, University of Washington James A. Christian, Louisiana Technical University Donald Drake, University of Hawaii Richard Churchill, Southern Maine Technical College Carolyn Dunn, University of North Carolina at Jerry A. Clonts, Anderson College Wilmington John Cruzan, Geneva College William Eisinger, Santa Clara University Kenneth J. Curry, University of Southern Mississippi James Gamer, Horry-Georgetown Technical College David B. Czarnecki, Loras College Susan Han, Un iversity of Massachusetts Stephen S. Daggett, Avila College A. Scott Holaday, Texas Tech University Raviprakash G. Dani, Texas Tech University Chad Jordan, North Carolina State University Roy Darville, East Texas Baptist University Sharon Klavins, University of Wisconsin-Platteville Bill D. Davis, Rutgers University Andrew McCubbin, Washington State University Jerry D. Davis, University of Wisconsin-LaCrosse Francis Putz, University of Florida John W. Davis, Benedictine College Jimmy Rozell, Tyler Junior College Roger del Moral, University of Washington  Preface XV Semma Dhir, Fort Valley State University William A. Jensen, Ohio State University Rebecca M. DiLiddo, Mount Ida College Cindy Johnson-Groh, Gustavus Adolphus College Susan C. Dixon, Walla Walla College Toney Keeney, Southwest Texas State Ben L. Dolbeare, Lincoln Land Community College Sekender A. Khan, Elizabeth City State University Patricia M. Dooris, Saint Leo College Joanne M. Kilpatrick, Auburn University-Montgomery Tom Dudley, Angelina College Helen G. Kiss, Miami University Jan Federic Dudt, Bartlesville Wesleyan College John Z. Kiss, Miami University of Ohio Diane Dudzinski, Washington State Community Kaoru Kitajima, University of Florida College Roger C. Klockziem, Martin Luther College Kerry B. Dunbar, Dalton State College Robert L. Koenig, Southwest Texas Junior College Carolyn S. Dunn, University of North Carolina- David W. Kramer, Ohio State University-Mansfield Wilmington Robert N. Kruger, Mayville State University Robert Ediger, California State University-Chico Martin LaBar, Southern Wesleyan University H. Herbert Edwards, Western Illinois University Vic Landrum, Washburn University William Eisinger, Santa Clara University James M. Lang, Greenville College Inge Eley, Hudson Valley Community College Brenda Price Latham, Merced College Thomas E. Elthon, University of Nebraska-Lincoln Cheryl R. Laursen, Eastern Illinois University Frederick B. Essig, University of South Florida Peter J. Lemay, College of the Holy Cross G. F. Estabrook, The University of Michigan Donald C. Leynaud, Wabash Valley College James Ethridge, Joliet Junior College Barbara E. Liedl, Central College Paul G. Fader, Freed-Hardeman University John F. Logue, University of South Carolina-Sumter Bruce Felgenhauer, University of Louisiana-Lafayette Elizabeth L. Lucyszyn, Medaille College Jorge F. S. Ferreira, Southern Illinois University- Karen Lustig, Harper College Carbondale Erin D. MacKenzie, Weatherford College David G. Fisher, Maharishi University of Management Paul Mangum, Midland College Rosemary H. Ford, Washington College Steve Manning, Arkansas State University-Beebe Stephen W. Fuller, Mary Washington College Michael H. Marcovitz, Midland Lutheran College Sibdas Ghosh, University of Wisconsin-Whitewater Bernard A. Marcus, Genesee Community College Mike Gipson, Oklahoma Christian University David Martin, Centralia College Katherine Glew, University of Washington Margaret Massey, Mississippi University for Women Richard Glick, Winston-Salem State University William J. Mathena, Kaskaskia College Charles Good, Ohio State University Alicia Mazari-Andersen, Kwantlen University College David L. Gorchov, Miami University of Ohio Joseph H. McCulloch, Normandale Community Scott A. Gordon, University of Southern Illinois College Govindjee, University of Illinois Julie A. Medlin, Northwestern Michigan College Steve Greenwald, Gordon College Larry Mellichamp, University of North Carolina at Sharon Gusky, Northwestern Connecticut Community Charlotte Technical College Richard G. Merritt, Houston Community College Timothy C. Hall, Texas A & M University Andrew S. Methven, Eastern Illinois University Mark Hammer, Wayne State College Timothy Metz, Campbell University Laszlo Hanzely, Northern Illinois University David H. Miller, Oberlin College Joyce Phillips Hardy, Chadron State College David W. Miller, Clark State Community College Nancy E. Harris, Elon College Lillian W. Miller, Elorida Community College- David Hartsell, Phillips Community College Jacksonville Jill F. Haukos, South Plains College Subhash C. Minocha, University of New Hampshire David L. Herrin, University ofTexas-Austin L. Maynard Moe, California State University- Peter Heywood, Brown University Bakersfield Jeffrey P. Hill, Idaho State University Beth Morgan, University of Illinois, Urbana- L. Michael Hill, Bridgewater College Champaign H. H. Ho, State University of New York-New Paltz Dale M. J. Mueller, Texas A & M University A. Scott Holaday, Texas Tech University Lytton John Musselman, Old Dominion University Elisabeth A. Hooper, Truman State University Nusrat H. Naqvi, Southern University Susan Houseman, Southeastern Community College Joanna H. Norris, University of Rhode Island Lauren D. Howard, Norwich University Chuks A. Ogbonnaya, Mountain Empire College Vernon R. Huebschwerlen, Reedley Community Jeanette C. Oliver, Elathead Valley Community College College Sebastine O. Onwuka, Lesley College Patricia L. Ireland, San Jacinto College, South Clark L. Ovrebo, University of Central Oklahoma XVI Preface A. D. Owings, Southeastern Louisiana University Barbara Greene Shipes, Hampton University Julie M. Palmer, University of Texas-Austin Richard H. Shippee, Vincennes University Richard A. Palmer, Fresno City College Brian R. Shmaefsky, Kingwood College Carolyn Peters, Spoon River College Shaukat M. Siddiqi, Virginia State University Martha M. Phillips, The College of St. Catherine Dilbagh Singh, Blackburn College Jerry L. Pickering, Indiana University of Pennsylvania Del William Smith, Modesto Junior College Wayne S. Pierce, California State University- James Smith, Boise State University Stanislaus Joanna M. K. Smith Indiren Pillay, Southwestern Tennessee Community Steven Smith, University of Arizona College Nancy Smith-Huerta, Miami University Mary Ann Polasek, Cardinal Stritch University F. Lee St. John, Ohio State University-Newark Dr. Robert J. Porra, CSIRO Spencer S. Stober, Alvernia College Kumkum Prabhakar, Nassau Community College Marshall D. Sundberg, Emporia State University Tyre J. Proffer, Kent State University Eric Sundell, University of Arkansas-Monticello V. Raghaven, The Ohio State University Donald D. Sutton, California State University- Mohammad A. Rana, St. Joseph College Fullerton Margene M. Ranieri, Bob Jones University Stan R. Szarek, Arizona State University W. T. Rankin, University of Montevallo Mesfin Tadesse, Ohio State University Dennis T. Ray, University of Arizona Max R. Terman, Tabor College Linda Mary Reeves, San Juan College R. Dale Thomas, Northeast Louisiana University Maralyn A. Renner, College of the Redwoods Stephen L. Timme, Pittsburgh State University Penelope ReVelle, Community College of Baltimore Leslie R. Towill, Arizona State University County-Essex Richard E. Trout, Oklahoma City Community College Tom Reynolds, University of North Carolina- Jun Tsuji, Sienna Heights College Charlotte Claudia Uhde-Stone, California State University- Stanley A. Rice, Southeastern Oklahoma State East Bay University Gordon E. Uno, University of Oklahoma Dennis F. Ringling, Pennsylvania College of Rani Vajravelu, University of Central Florida Technology John Vanderploeg, Ferris State University Daryl Ritter, Okaloosa-Walton Community College Delmar Vander Zee, Dordt College Suzanne M. D. Rogers, Salem International University C. Gerald Van Dyke, North Carolina State University Wayne C. Rosing, Middle Tennessee State University Leon Walker, University of Findlay Robert G. Ross, University of Puerto Rico Betty J. Washington, Albany State University Jimmy Rozell, Tyler Junior College Edgar E. Webber, Keuka College Manfred Ruddat, University of Chicago Christopher R. Wenzel, Eastern Wyoming College Patricia Rugaber, Coastal Georgia Community College Cherie Wetzel, City College of San Erancisco Robert M. Rupp, Ohio State University, Agricultural Ingelia White, Windward Community College Technical Institute Garrison Wilkes, University of Massachusetts-Boston Thomas H. Russ, Charles County Community College Donald L. Williams, Sterling College Dennis J. Russell, University of Alaska Southeast Justin K. Williams, Sam Houston State Universitv Connie Rye, Bevill State Community College Marvin Williams, University of Nebraska-Kearney C. L. Sagers, University of Arkansas Dwina W. Willis, Ereed-Hardeman University A. Edwards Salgado, Christian Brothers University James A. Winsor, The Pennsylvania State University Thomas Sasek, Northeast Louisiana University Clarence C. Wolfe, Northern Virginia Community Michael A. Savka, University of West Florida College Neil W. Sawyer, University of Wisconsin-Whitewater Chris Wolverton, Ohio Wesleyan University Neil Schanker, College of the Siskiyous Kathleen Wood, University of Mary Hardin-Baylor Renee M. Schloupt, Delaware Valley College Richard J. Wright, Valencia Community College Bruce S. Serlin, DePauw University Todd Christian Yetter, Cumberland College Wilbur J. Settle, State University of New York- Brenda Young, Daemen College Oneonta Rebecca Zamora, South Plains College v  Preface XVII Teaching and Learning Supplements McGraw-Hill offers various tools and technology products to textbooks that can be used to create customized lectures, support Stem's Introductory Plant Biology. Students can order visually enhanced tests and quizzes, compelling course supplemental study materials by contacting their local bookstore websites, or attractive printed support materials. All assets or by calling 800-262-4729. Instmctors can obtain teaching aids are copyrighted by McGraw-Hill Higher Education, but can by calling the Customer Service Department at 800-338-3987, be used by instructors for classroom purposes. visiting the McGraw-Hill website at www.mhhe.com, or con¬ Answer Keys and Instructor’s Manual Answers are tacting their local McGraw-Hill sales representative. available to review questions and discussion questions from the textbook, as well as lab manual answers, to help make your teaching easier. An Instructor’s Manual with chapter overviews and detailed lecture outlines is also available. TEACHING SUPPLEMENTS Computerized Test Bank A comprehensive bank of test FOR INSTRUCTORS questions is provided within a computerized test bank pow¬ ered by McGraw-Hill’s flexible electronic testing program Book-Specific Website EZ Test Online. EZ Test Online allows you to create paper and online tests or quizzes in this easy-to-use program! A new tagging scheme allows you to sort questions by dif¬ ficulty level, topic, and section. Imagine being able to create TMte and access your test or quiz anywhere, at any time, without Prwfmct0* CoottnB Stem's Introductory Plant Sk>togy. 12/e FeMu' «f New te Thi* EdIOen And Hence Jcmos E MUcb end SHeSey H. Jemky installing the testing software. Now, with EZ Test Online, ISdN; 00730*0529 Cuctoni ^btlstunf About the Authors list of Chonges CoevrtghtyMn 2011 instructors can select questions from multiple McGraw-Hill MMtome lO the Stem wehuiel Tlib Mkuble onKne tool bdeslgned toenhetice your tvamitig uiid help you siKceed In your course Book specifk (onleni such as Qui/2iiiti Aashcettls, cltepler oiiillnes end turnmertes. end web Hnks can ell be etcosed by choosing front the'Student Edition' to tise lelL test banks or compose their own, and then either print the test for paper distribution or give it online. Test Creation To Obtain an Instructor lo^n (or this teebsiie. ash your loc4 sales representehtie K you're an Instructor thiniilng about adopting thhiestbooh. rerarest a free copy for review. Author/edit questions online using the 14 different OZOU Ncerew-Hill Hlgtier edueitwn Any cee IS sublet trw femt or me end ptrvacv HcnM>. Ncgfew-HiH Krarar ECucatKm * * ene of ON manv fine Mibnesses ef TTw MeCf«n-.HIur:oinMe«fS question type templates Create question pools to offer multiple versions online—great for practice McGraw-Hill’s Website (http://www.mhhe.com/sternl2e) Export your tests for use in WebCT, Blackboard, for Stern’s Introductory Plant Biology is a text-specific PageOut, and Apple’s iQuiz website offering an extensive array of teaching and learning Share tests easily with colleagues, adjuncts, TAs tools. In addition to all of the student assets available, this Botany e-Atias Over 800 photographs, from acorns to site includes the following: zinnia flowers, were taken by photographer Steven P. Lynch. Presentation Tools Everything you need for outstanding Arranged alphabetically, these photos can be printed or used presentation in one place! This easy-to-use table of assets in your own custom lectures and presentations. includes Image PowerPoints—Both labeled and unlabeled versions of art have been included for different types of presenta¬ McGraw-Hill's tions, as well as tables and photographs from the text. Biology Digitized Lecture PowerPoints with animations fully embedded. Videos Animations—Numerous full-color animations illustrating important processes are also provided. Harness the visual (ISBN: 978-0-07- impact of concepts in motion by importing these tiles into 312155-0; MHID: classroom presentations or online course materials. 0-07-312155-X) Labeled and unlabeled JPEG images—Lull-color digital Licensed from some of the highest-quality life science files of all illustrations that can be readily incorporated video producers in the world, these brief video clips on into presentations, exams, or custom-made classroom DVD range in length from 15 seconds to two minutes and materials. cover all areas of general biology, from cells to ecosystems. Presentation Center In addition to the images from your Engaging and informative, McGraw-Hill’s digitized biology book, this online digital library contains photos, artwork, videos will help capture students’ interest while illustrating animations, and other media from an array of McGraw-Hill key biological concepts, applications, and processes. XVIII Preface instruction utilize plants to introduce biological principles and the scientific method. They are written to allow for maximum This classroom performance system (CPS) utilizes wire¬ flexibility in sequencing. less technology to bring interactivity into the classroom or lecture hall. Instructors and students receive immediate feedback through wireless response pads that are easy to use and engage students, elnstruction can assist instructors by Oegrlty campus Taking attendance Administering quizzes and tests Tegrity Creating a lecture with intermittent questions McGraw-Hill Tegrity Campus™ is a service that makes class time available all the time by automatically capturing every Using the CPS grade book to manage lectures and lecture in a searchable format for students to review when student comprehension they study and complete assignments. With a simple one-click Integrating interactivity into PowerPoint presentations start and stop process, you capture all computer screens and Contact your local McGraw-Hill sales representative for corresponding audio. Students replay any part of any class more information. with easy-to-use browser-based viewing on a PC or Mac. Educators know that the more students can see, hear, and experience class resources, the better they learn. With Course Delivery Systems Tegrity Campus, students quickly recall key moments by using Tegrity Campus’s unique search feature. This search With help from WebCT, Blackboard, and other course helps students efficiently find what they need, when they management systems, professors can take complete control need it across an entire semester of class recordings. Help of their course content. Course cartridges containing web¬ turn all your students’ study time into learning moments site content, online testing, and powerful student tracking immediately supported by your lecture. features are available upon request for use within these To learn more about Tegrity, watch a two-minute Flash platforms. demo at http://tegritycampus.mhhe.com The Amazing Lives of Plants: The LEARNING SUPPLEMENTS Reproductive Lives of Mosses^ Pines, FOR STUDENTS Ferns, Flowers, and Leaves Website (http://www.mhhe.com/sternl2e) CD-ROM OR DVD (CD ISBN: 978-0- 07294047-3; CD MHID: 0-07-2940476) This site offers a wide variety of student resources that provide students many opportunities to master the core (DVD ISBN: 978-0-07-294339-9; concepts in botany. Learn more about the exciting features DVD MHID: 0-07-294339-4) provided for students through Stern’s Introductory Plant Available upon adoption. The Amazing Lives of Plants Biology website: includes five independent segments: “Mosses,” “Ferns,” Practice quizzing “Pines,” “Flowers,” and “Leaves.” Their reproductive lives Botany e-Atlas are presented in a vivid full-color combination of live video footage and sharp animation. Subtitled text makes it easy Weblinks on chapter topics to cue up for use in lecture, and the pace of the program is Key term flashcards suitable for students taking notes. Career information Stern's Introductory Plant Biology Electronic Books Laboratory Manual, Twelfth Edition^ McGraw-Hill has partnered with CourseSmart to bring you an innovative and inexpensive electronic textbook. Save up to by Bidlack 50% off the cost of a printed book, reduce impact on the envi¬ (ISBN: 978-0-07-304053-0; ronment, and gain access to powerful web tools for learning MHID: 0-07-304053-3) including full text search, notes and highlighting, and e-mail tools for sharing notes between classmates. eBooks from The laboratory manual that accompanies Stern’s Introductory McGraw-Hill are smart, interactive, searchable, and portable. Plant Biology has been revised and updated. It is written for To review complimentary copies or to purchase an the student who is entering the study of botany. The exercises eBook, go to http://www.CourseSmart.com Overview Some Learning Goals The Relationship of Humans to Their Environment Human and Animal Dependence on Plants Botany as a Science Hypotheses Microscopes Diversification of Plant Study Plant Sciences Inquiry: Plant Biology and the Internet Summary Review Questions Discussion Questions Additional Reading Learning Online A mountain iris (Iris missouriensis) growing along a slope near the roadside in the Carson National Forest, New Mexico. This chapter introduces you to botany: what it is, how it developed, how it relates to our everyday lives, and what its potential is for the future. The discussion includes a brief introduction to some common questions about plants and their functions, an examination of the scientific method, and a brief look at botany after the invention of the microscope. It concludes with a brief survey of the major disciplines within the field of botany. Some Learning Goals 1. Understand how humans have impacted their environment, 3. Explain how and why all life is dependent on green organisms. particularly during the past century. 4. Be able to indicate briefly the particular aspects of botany with 2. Describe how hypotheses are formulated and used in the which each of the major botanical disciplines is concerned. scientific method. bile in high school in southern Africa, I was When a botanist friend of mine invited me to his office once invited to a friend’s farm during spring to see a 20-gallon glass fish tank he had on his desk, I break. One day as I was returning to the farm¬ expected to find a collection of house plants or tropical fish. house from a walk around the farm, I heard Instead, I saw what at first appeared to be several small, erect groaning coming from inside. I learned that my friend’s sticks that had been suspended in midair with large rubber father had been clearing cactuslike Euphorbia plants from bands; there were also beakers of water in the comers. When some land. The plants produce a poisonous milky latex, I got closer, I could see that the “sticks” were cuttings (seg¬ which the father had taken great care to wash thoroughly ments) of poplar twigs that were producing roots at one end from his hands. Absentmindedly, however, he had splashed and new shoots at the other end. The roots, however, were some of the water in his face, and traces of the poison had gotten into his eyes, causing great pain. Another family member immediately ran to the nearby barn and obtained some colostrum milk from a cow that had just given birth. The eyes were bathed in the milk, which contains an anti¬ dote for that particular poison, and the pain subsided. I was told that if the milk had not been quickly available, the man would have been blind within half an hour. In Venezuela and Brazil, however, cow trees (e.g., Brosimum utile; Mimusops huberi) produce a sweet, nutritive latex that is relished by the natives of the region. Still other plants such as opium poppies produce latex that contains narcotic and medicinal drugs (Fig. 1.1). Why do plants such as Euphorbia species produce poisons, while parts of so many other plants are perfectly edible, and some produce spices, medicines, and a myriad of products useful to humans? In late 1997, a fast-food chain began airing a televi¬ sion commercial that showed a flower of a large potted plant gulping down a steak sandwich. Most of us have seen at least pictures of Venus’s flytraps and other small plants that do, indeed, trap insects and other small animals, but are there larger carnivorous plants capable of devouring big sand¬ wiches or animals somewhere in remote tropical jungles? Occasionally we hear or read of experiments—often associated with school science fairs—that suggest plants respond in some positive way to good music or soothing talk; conversely, some plants are said to grow poorly when Figure 1.1 immature opium poppy capsules that were gashed they are harshly yelled at. Do plants really respond to their with a razor blade. Note the opium-containing latex oozing from surroundings, and, if so, how and to what extent? the gashes. 2  What Is Plant Biology? 3 Figure 1.2 Cuttings (segments) of twigs that were suspended upside down in a humid, lighted glass tank. New roots are growing down from the top ends, and new shoots are growing up from the bottom. growing down from the tops of the cuttings, and the shoots were growing upward from the bottoms (Fig. 1.2). My friend had suspended the cuttings upside down, and new roots and shoots were being produced in the humid, lighted surround¬ ings of the fish tank—regardless of the orientation of the cut¬ tings. If I’d seen such bizarre plants in a movie, I might have thought that the fiction writers had imagined something that didn’t exist. There right in front of me, however, were such plants, and they were real! When cuttings are separated from the parent plant, how do they “know” which end is up, and why would the roots and shoots grow the way they did? California’s huge coastal redwoods and Tasmania’s giant gum trees can grow to heights of 90 or more meters (300 or more feet). When these giant trees are cut down, there is no evidence of pumps of any kind within them. How then does water get from the roots below ground to the tops of these and other trees? How does food manufactured in the leaves get down to the roots (Fig. 1.3)? Our tropical rain forests, which occupy about 5% of the earth’s surface, are disappearing at the rate of several acres a minute as the plant life is cleared for agriculture, wood sup¬ plies (primarily for fuel), cattle ranching, and other human activities such as mining for gold. Is the dwindling extent of our rain forests, which are home to 50% of all the species of living organisms, cause for alarm? Or will the same plant and animal life return if the human activities cease? There is currently much debate about global warming and the potential effects on life as we know it. Are those who proclaim that global warming will eventually have disas¬ trous effects on modern civilization and living organisms simply exaggerating, or is there a scientific basis for the Figure 1.3 Califormla coastal redwoods {Sequoia semper- claims? What about the many forms of pollution that exist? virens). Coastal redwoods may grow for thousands of years and Will we be able to overcome the effects of pollution? some may reach heights of nearly 100 meters (330 feet). 4 Chapter 1 Plant life constitutes more than 98% of the total biomass (collective diy weight of living organisms) of the earth. Plants and other green organisms have the exclusive capacity to pro¬ duce oxygen while converting the sun’s energy into forms vital to the existence of both plant and animal hfe. At the same time, Expanding human populations and increasing inten¬ plants remove the large amounts of carbon dioxide given off sity of human activity now threaten the earth's popu¬ by all living organisms as they respire. In other words, virtually lations, which are critical to the ecological integrity all living organisms are totally dependent on green organisms of the biosphere. These global-scale threats include for their existence. If some major disease were to kill off all global warming, pollution, aquifer depletion, and or most of the green organisms on land and in the oceans and widespread land clearing. Reducing or reversing these lakes, all the animals on land, in the sea, and in the air would environmental challenges will require applying mea¬ soon starve. Even if some alternative source of energy were sures such as recycling of wastes, returning organic available, animal life would suffocate within 11 years—the matter to soils, and using plants to reclaim damaged time estimated for all the earth’s oxygen to be completely used land. As we attempt to build a sustainable future, we up if it were not replaced. Just how do green plants capture the should bear in mind that while plants can live without sun’s energy, use carbon dioxide, and give off oxygen? humans, we cannot live for long without plants. This book tries to answer these and other questions about living organisms—particularly those pertaining to plants, algae, fungi, and bacteria. Moreover, additional information about plant biology related to future societies, conservation, done in a manner that prevents topsoil erosion, and the prac¬ and human benefits is discussed. tice of clearing brush with chemicals will have to be abolished. Industrial pollutants will have to be rendered harmless and recycled whenever possible. Many products that now are still largely discarded (e.g., THE RELATIONSHIP OF HUMANS garbage, paper products, glass, metal cans) will also have to be recycled on a much larger scale. Biological pest con¬ TO THEIR ENVIRONMENT trols (discussed in Appendix 2) will have to replace the use It has been estimated that the total human population of the of poisonous controls whenever possible. Water and energy world was less than 20 million in 6000 B.c. During the next conservation will have to be universally practiced, and rare 7,750 years, it rose to 500 million; by 1850, it had doubled to plant species, with their largely unknown gene potential for 1 billion; and 70 years later, it had doubled again to 2 billion. future crop plants, will need to be saved from extinction by The 4.48-billion mark was reached in 1980, and within preservation of their habitats and by other means. The gen¬ 5 years, it had grown to 4.89 billion. It is presently increas¬ eral public will have to be made even more aware of the ing by nearly 80 million annually, and estimates for the year urgency for wise land management and conservation—which 2009 are over 6.7 billion. By 2025 it is believed the world’s will be especially needed when pressures are exerted by population will exceed 7.8 billion. The earth remains con¬ influential forces promoting unwise measures in the name stant in size, but the human population continues to grow. of “progress”—before additional large segments of our In feeding, clothing, and housing ourselves, we have natural resources are irreparably damaged or lost forever. had a major impact on our environment. We have drained Alternatives appear to be nothing less than death from starva¬ wetlands and cleared natural vegetation from vast areas of tion, respiratory diseases, poisoning of our food and drink, land. California, for example, now has less than 5% of the and other catastrophic events that could ensure the premature wetland it had 100 years ago. We have dumped wastes and demise of large segments of the world’s population. other pollutants into our waters, and added pollutants to the Scientists and, increasingly, the general public, have atmosphere. We have killed pests and plant disease organ¬ become alarmed about the effects of human carelessness isms with poisons. These poisons have also killed natural on our environment. Since the 1980s, damage to forests and predators and other useful organisms, and, in general, have lakes caused by acid rain, the “greenhouse effect,” contami¬ disrupted the delicate balance of nature that existed before nation of ground water by nitrates and pesticides, reduction humans began degrading their natural surroundings. of the ozone shield, major global climatic changes, loss of If we are to survive on this planet beyond the 21st century, biodiversity in general, and loss of tropical rain forests in there is little question that humans have to stop increasing particular have gained widespread publicity. in numbers, and the many unwise agricultural and industrial practices that have accompanied the mushrooming of human Human and Animal populations must be replaced with practices more in tune with restoring some ecological balance. Agricultural practices of Dependence on Plants the future will have to include the remrn of organic material Our dependence on green organisms to produce the oxygen in to the soil after each harvest, instead of adding only inorganic the air we breathe and to remove the carbon dioxide we give off fertilizers. Harvesting of timber and other crops will have to be doesn’t stop there. Plants are also the sources of products that  What Is Plant Biology? 5 Figure 1.4B Part of a produce section in a supermarket. I«isi\n3|CE is: ANDflKiCE 1 ^ICE iSjJ^ Bsnci islmEg : IS j^i |mLL SE^H WEE|Wl WM.SBlAMOmSm WMCU ISIA^' ISlAT^ Figure 1.4A Rice cakes being manufactured. Unprocessed rice is poured into small ovens where the kernels are expanded. The kernels are then compressed into cakes, which are conveyed Figure 1.5 Some of the spices derived from plants. by belt to a packaging area. are so much a part of human society that we largely take them Although shortages of oil and other fossil fuels may for granted. We know, of course, that wheat, rice, com, pota¬ sometimes be politically or economically manipulated, toes, and other vegetables are plants (Fig. 1.4); but all foods, there is no question that these fuels are finite and eventually including meat, fish, poultry, eggs, cheese, and milk, to mention will disappear. Accordingly, the development of alternative just a few, owe their existence to plants. Condiments such as energy sources is receiving increased attention. spices (Fig. 1.5) and luxuries such as perfumes are produced by Methane gas, which can be used as a substitute for natu¬ plants, as are some dyes, adhesives, digestible surgical stitching ral gas, has been produced from animal manures and decom¬ fiber, food stabilizers, beverages (Fig. 1.6), and emulsifiers. posed plants in villages in India and elsewhere for many Our houses are constructed with lumber from trees, years, and after several years of trial on a small scale in the which also furnish the cellulose for paper, cardboard, and syn¬ United States, the production of methane on a larger scale thetic fibers. Some of our clothing, camping equipment, bed¬ from human sewage is being investigated. ding, draperies, and other textile goods are made from fibers Corn, switchgrass, and other sources of carbohydrates of many different plant families (Fig. 1.7). Coal is fossilized are currently used in the manufacture of ethanol, which plant material, and oil came from microscopic green organ¬ is blended with gasoline. Most cars in the United States isms or animals that either directly or indirectly were plant can run on fuel containing up to 10% ethanol. Flexible consumers. All medicines and drugs at one time came from fuel vehicles have been designed to use fuel blends con¬ plants, fungi, or bacteria, and many important ones, includ¬ taining up to 85% ethanol. In 2007, 115 ethanol plants in ing most of the antibiotics, still do (Fig. 1.8). Microscopic 19 states produced 6.5 billion gallons of ethanol, which was organisms play a vital role in recycling both plant and ani¬ 38% more than the ethanol produced the previous year. mal wastes and aid in the building of healthy soils. Others are Additional plants will be operational in the near future. responsible for human diseases and allergies. The Energy Policy Act of 2005 mandates that annual 6 Chapter 1 Figure 1.7 Cotton plants. The white fibers, in which seeds Figure 1.6A Ripening coffee berries. They are picked by are embedded, are the source of textiles and fabrics. The seeds hand when they are red. The seeds are extracted for roasting after are the source of vegetable oils used in margarine and shortening. the berries are fermented. After the oils have been extracted, the remaining "cotton cake" is used for cattle feed. Figure 1.8 a PenicHHum colony. The tiny beads of fluid on the surface contain penicillin, widely used as an antibiotic. renewable fuel production in the United States will reach 7.5 billion gallons by 2012. Currently, ethanol fuel in the U.S. is mainly produced from corn, but there are concerns about losing food crop land to produce fuel. In addition, the energy and pollution balance of ethanol production is under debate. Cellulosic ethanol, which is derived from inedible plant fiber, such as wood chips or switchgrass, may overcome some of these concerns. What about plants and the future? As you read this, the population of the earth already has exceeded 6.7 billion per¬ sons, every one of whom needs food, clothing', and shelter in order to survive. To ensure survival, we may need to learn not only how to cultivate food plants but also how to use plants in removing pollutants from water, air, and soil (Fig. 1.9), in making land productive again, and in renewing urban areas. In addition, we may need to be involved in helping halt the Figure 1.6B Coffee beans cooling after being roasted. destruction of plant habitats caused primarily by the huge  What Is Plant Biology? 7 interest in plants was mostly practical and centered around how plants might provide food, fibers, fuel, and medi¬ cine. Eventually, however, an intellectual interest arose. Individuals became curious about how plants reproduced and how they were put together. This inquisitiveness led to plant study becoming a science, which broadly defined is simply “a search for knowledge of the natural world.” Botanists are scientists who study plants. A science is distinguished from other fields of study by sev¬ eral features. It involves the observation, recording, organiza¬ tion, and classification of facts, and more important, it involves what is done with the facts. Scientific procedure involves the process of experimentation, observation, and the verifying or discarding of information, chiefly through inductive reasoning from known samples. There is no universal agreement on the precise details of the process. A few decades ago, scientific pro¬ cedure was considered to involve a routine series of steps that Flgur6 1.9 A polluted waterway in an urban area. involved first asking a question, then formulating a hypothesis, followed by experiments, and finally developing a theory. This series of steps came to be known as the scientific method, and increase in the number of earth’s inhabitants. This subject and there are still instances where such a structured approach works related matters are further discussed in Chapter 25. well. In general, however, the scientific method now describes At present the idea that humanity may not be able to save the procedures of developing and testing hypotheses. itself may seem radical, but there are a few who have sug¬ gested that it might become necessary in the future to emigrate to other planets. Regardless of humanity’s future, it is essen¬ Hypotheses tial that our understanding of plants be used to sustain life on A hypothesis is simply a tentative, unproven explanation for this and maybe even other planets. Experiments with porta¬ something that has been observed. It may not be the correct ble oxygen generators have been in progress for many years. explanation—testing will determine whether it is correct Tanks of water teeming with tiny green algae are taken aboard or incorrect. To be accepted by scientists, the results of any a spacecraft and installed so that they are exposed to light for experiments designed to test the hypothesis must be repeat- at least part of the time. The algae not only produce oxygen, able and capable of being duplicated by others. which the spacecraft inhabitants can breathe, but they also uti¬ The nature of the testing will vary according to the cir¬ lize the waste carbon dioxide produced by respiration. As the cumstances and materials, but good experiments are run in algae multiply, they can be fed to a special kind of shrimp, two forms, the second form being called a control. In the which in turn multiply and become food for the space travel¬ first form, a specific aspect, or variable, is changed. The ers. Other wastes are recycled by different microscopic organ¬ control is run in precisely the same way but without chang¬ isms. When this self-supporting arrangement, called a closed ing the specific aspect, or variable. The scientist then can be system, is perfected, the range of spacecraft should greatly sure that any differences in the results of the parallel experi¬ increase because heavy oxygen tanks will not be necessary, ments are due to the change in the variable. and the amount of food reserves needed will be reduced. For example, we may observe that a ripe orange we have Today, teams of botanists, anthropologists, and medi¬ eaten tastes sweet. We may then make the hypothesis that all cal doctors are interviewing medical practitioners and herbal ripe citrus fruits taste sweet. We may test the hypothesis by healers in remote tropical regions and taking notes on vari¬ tasting oranges and other citrus fruits such as tangerines and ous uses of plants by the local inhabitants. These scientists lemons. As a result of our testing (since lemons taste sour), are doing so in the hope of preserving at least some plants we may modify the hypothesis to state that only some ripe with potential for contributions to modern civilization before citrus fruits are sweet. In such an experiment, the variable disruption of their habitats results in their extinction. involves more than one kind of ripe citrus fruit; the control, on the other hand, involves only ripe oranges. When a hypothesis is tested, data (bits of information) BOTANY-AS A SCIENCE 9 are accumulated and may lead to the formulation of a useful generalization called a principle. Several related principles The study of plants, called botany—from three Greek words, may lend themselves to grouping into a theory, which is botanikos (botanical), botane (plant or herb), and boskein (to not simply a guess. A theory is a group of generalizations feed), and the French word botanique (botanical)—appears (principles) that help us understand something. We reject to have had its origins with Stone Age peoples who tried to or modify theories only when new principles increase our modify their surroundings and feed themselves. At first, the understanding of a phenomenon. 8 Chapter 1 rings of wood of known age. Plant anatomy is also used Microscopes to solve crimes. Forensic laboratories may use fragments The microscope is an indispensable tool of most botanists, of plant tissues found on clothing or under fingernails to and biologists in general. This instrument traces its origin determine where a crime took place or if certain persons to 1590, when a family of Dutch spectacle makers found they could have been present where the crime was committed. could magnify tiny objects more than 30 times when they The anatomy of leaves, stems, and other plant parts is used combined two convex lenses in a tube; they also found to unravel and sort out relationships among plants. A form they could make minute objects visible with the magnifica¬ of plant anatomy, known as paleobotany, involves the study tion their instrument achieved. A few decades later, a Dutch of plant fossils. draper—Anton van Leeuwenhoek (1632-1723)—ground Plant physiology, which is concerned with plant func¬ lenses and eventually made 400 microscopes by hand, some tion, was established by J. B. van Helmont (1577-1644), a of which could magnify up to 200 times. Modern micro¬ Flemish physician and chemist, who was the first to dem¬ scopes, discussed in Chapter 3, can produce magnifications onstrate that plants do not have the same nutritional needs of more than 200,000 times and are leading almost daily to as animals. In a classic experiment, van Helmont planted new discoveries in biology. a willow branch weighing 5 pounds in an earthenware tub filled with 90.7 kilograms (200 pounds) of dry soil. He covered the soil to prevent dust from settling on it from the DIVERSIFICATION