Introduction to Plants and Botany PDF

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© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LL NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION CHAPTER 1 NOT FOR SALE OR DISTRIBUTION Introduction to © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC OUTLINE NOT FOR SALE OR DISTRIBUTION Concepts Plants and Botany Plants Scientific Method © Jones & Bartlett Learning, LLC Areas Where the Scientific © Jones Method & Bartlett Learning, LL NOT FOR SALE OR DISTRIBUTION Is Inappropriate NOT FOR SALE OR DISTRIBUT LEARNING OBJECTIVES Using Concepts to Understand Plants After reading this chapter, students will be able to: Origin and Evolution of Plants Recognize the relationship between plants and climate change. Diversity of Plant Adaptations © Jones & Bartlett Learning, LLC Describe the difficulty in creating a singular definition of a plant. © Jones Plants& Bartlett Versus theLearning, LLC Study of Plants ListNOT FOR SALEtenets four fundamental OR DISTRIBUTION of the scientific method. NOT Box FOR SALE 1-1 Plants andOR DISTRIBUTION People: Plants and Give an example of an area where the scientific method is People, Including Students inappropriate. Box 1-2 Plants and People: The Summarize the fundamental concepts related to the study of plants. Characteristics of Life © Jones & Bartlett Learning, LLC © Jones Order the process of evolution from early prokaryote to plant. & Bartlett BoxLearning, 1-3 Plants andLLC People: Algae and NOT FOR SALE OR DISTRIBUTION Provide two examples of plant adaptations. NOT FOR SALE OR DISTRIBUTION Global Warming Explain the difference between observation and interpretation. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LL Did You Know? NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT Chapter Opener Image: People and animals must have oxygen to live. Without oxygen, we would die of asphyxiation. The plants here are photosynthesizing E arly humans were weaving fibers of flax plants into rough in the sunshine, producing the oxygen we need. The roots of these trees hold the soil in place, even on steep clothing as early © Jones as 36,000 years & Bartlett ago. Learning, LLC © Jones &Without slopes. Bartlett the trees,Learning, LLC rain would wash all the soil Vanilla, NOTchocolate, FOR SALE coffee, ORtea,DISTRIBUTION cinnamon, and mint are all made NOT FOR SALE away leaving OR just bare DISTRIBUTION rock and this river would flood from plants. after every rain or be almost dry when there is a dry Plant products kill tens of thousands of people every year, not period. Global warming is causing less snowfall (and only through accidental poisoning but through cancer caused more snow melt) in mountains; this alters river flow and the suitability of the area for plants and animals. by smoking tobacco. © Jones & SBartlett cience andLearning, the scientific LLC © Jones method are a simple set of accepted rules&Bartlett Learning, Worthington Glacier,LLCAlaska. NOT FOR SALE about the ways in which evidence can be gathered and processed. SALE OR DISTRIBUTION OR DISTRIBUTION NOT FOR 1 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.  ❚❚ Concepts In addition to respiration and burning, carbon dioxide is added to the air as volcanoes erupt and as magma (molten © Jones Earth & Bartlett Learning, is becoming LLC is more frequent, and© Jones hotter, flooding rock) & comesBartlett upwardLearning, at mid-oceanLLC ridges between the giant NOT FORweather SALEis more OR DISTRIBUTION violent because we burn coal, oil, and other NOT FOR tectonic SALE plates OR that DISTRIBUTION carry the continents on Earth’s surface. fossil fuels, which releases carbon dioxide into the atmo- Carbon dioxide is also removed as certain algae build shells sphere. Carbon dioxide is one of several greenhouse gases of calcium carbonate: All limestone rock on Earth is com- that allow visible sunlight to pass through the atmosphere posed of vast numbers of microscopic shells of certain algae, and strike Earth’s surface, heating it. The warmer rocks, soil, clams, and other marine animals. At times in the past volca- © Jones & Bartlett Learning, and water give off infrared radiation back out toward space, LLC noes were very active and © added Jones carbon & Bartlett dioxide Learning, LL faster than NOT FOR SALE OR but greenhouse gases absorb infrared light and heat the DISTRIBUTIONphotosynthesis could remove NOT it, FOR causing EarthSALEto heat OR up. DISTRIBUT At atmosphere. It is a simple relationship: The higher the con- other times they were inactive and photosynthesis outpaced centration of greenhouse gases in the atmosphere, the hotter volcanism and Earth cooled. the climate. As Earth becomes hotter, more water evaporates Neither heating nor cooling has ever been severe enough out of the oceans into the air, where it then falls as heavy to risk killing all life on Earth. Instead, when Earth was © Jones & Bartlett Learning, LLC rains, causing flooding throughout the world. The warmer warm, rains ©were Jones & Bartlett also heavy (because Learning, of the warm oceans),LLC NOT FOR SALE OR DISTRIBUTION air also causes snow and ice on mountain tops to melt faster, so plants NOT grew FOR faster and SALE more OR abundantly,DISTRIBUTION absorbing more increasing flooding. Every summer brings more mudslides carbon dioxide. When plants take most of the carbon dioxide in California, larger floods on the Mississippi and other out of the air, Earth cools and dries, and plant growth slows. rivers, and more violent tornadoes and hurricanes. This is Today, we are at an unusually cool period in Earth’s his- global warming, also known as global climate change. tory. Plants have taken so much carbon dioxide out of the air © Jones & Bartlett Learning, LLC What does this have to do with botany? Everything. Plants © Jones there & Bartlett is almost noneLearning, to trap the sun’s LLCheat. We are actually NOT FORinSALE the sun OR DISTRIBUTION photosynthesize; that is, they take carbon dioxideNOT in FORan ice SALEage right ORnow, DISTRIBUTION known as the Pleistocene Ice Age, out of the air and use it to make the chemicals that compose but we are in its warm period (called the Holocene warm their bodies. Most of the weight of leaves, stems, roots, flow- period), known as an interglacial period (cold periods of ice ers, fruits, and seeds is carbon that was carbon dioxide in the ages are called glacials because glaciers are then common on air before plants captured it. As plants photosynthesize, they almost all mountains). Is it bad that Earth is unusually cool? © Jones & Bartlett Learning, remove carbon dioxide from the air and lock it into their bod- LLC Should we be burning even © more Jones petroleum & Bartlett and Learning, LL coal to heat ies, helping to keep Earth NOT cool FOR SALE ORtheDISTRIBUTION and counteracting warm- it up? NOT FOR SALE OR DISTRIBUT ing we are causing. An important question now is “Can plants The current coolness is exceptional, but it is the climate remove enough carbon dioxide from the air to counteract the in which we evolved and became distinct from the other damage we are doing?” The answer is “probably not.” great apes. It is also the climate in which most of our food The balance between the addition of atmospheric carbon plants evolved: Wheat, rye, barley, and corn are grasses that © Jones & Bartlett Learning, LLC dioxide by us and its removal by plants is affected by several flourish © under Jones cool, dry & Bartlett conditions. Learning, Grasses grow on LLC open, NOT FOR SALE OR DISTRIBUTION factors that are easy to understand. All animals, fungi, bacte- treeless NOT plains, but FOR when SALE Earth is OR warm DISTRIBUTION most of its surface is ria, and other nonphotosynthetic organisms produce carbon covered by forests, and grasses do not grow well in the shade dioxide just by being alive. As our bodies “burn” our food below trees. You may know that a significant step in the evo- (technically, as they respire it), carbon dioxide is produced; lution of us modern humans is that, unlike our ancestors therefore, animals (including humans) have been adding who were adapted to living in trees, we gradually evolved to © Jones & Bartlett Learning, LLC carbon dioxide to the atmosphere for billions of years. The © Jones & Bartlett walk upright Learning, on the ground, freeingLLCour forelimbs (our arms) NOT FORreal SALE OR DISTRIBUTION problem began when our ancestors discovered fire: NOT FOR such thatSALE we could OR use DISTRIBUTION our hands for holding and manipulat- We then began burning wood and coal and, more recently, ing tools. We did not come down out of the trees until open petroleum, natural gas, and other fossil fuels, adding carbon grasslands finally appeared on Earth, and those came about dioxide to the air in huge quantities. Until our mastery of in the last 30 million years as Earth became cooler, drier, and fire, plants were actually taking carbon dioxide out of the air the forests receded, all due to plant photosynthesis. faster than our respiration© Jones was adding & it.Bartlett Learning, LLCMore recently, we people© began Jones & Bartlett to cultivate Learning, LL our own NOT FOR SALE OR DISTRIBUTION Photosynthesis originated 2.8 billion years ago, and the food. Agriculture is new, havingNOT FOR separate, SALE independent OR DISTRIBUT ori- amount of carbon dioxide in the air has decreased and Earth gins in Europe, Asia, Africa, and the Americas less than has cooled, until the start of the Industrial Revolution when about 11,000 years ago. That is a significant number: The we began burning massive amounts of fuel. If photosynthe- current interglacial period we are living in now began only sis has been removing carbon dioxide from the atmosphere, 14,000 years ago. Snow and ice began to melt away, people © Jones & Bartlett Learning, LLC does that mean there was more carbon dioxide in the air spread across © Jones more of the & land, Bartlett and someLearning, humans made LLCthe NOT FOR SALE OR DISTRIBUTION in the past? And, if so, was Earth warmer in the past? The journey fromNOT Asia FOR to the SALE Americas ORat DISTRIBUTION that time. In the very answer to both questions is yes. Earth formerly had much short time of just a few thousand years between 14,000 years more carbon dioxide in its atmosphere and consequently ago and 11,000 years ago, humans progressed from being was much hotter. Earth’s climate is changing now, but it has wandering hunter-gatherers to starting the first farms, then always been changing and has never stayed the same for long establishing villages and towns, and then civilization began © Jones & Bartlett periods of time.Learning, LLC © Jones & Bartlett with art, writing, religion,Learning, and science. LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 2 Chapter 1: Introduction to Plants and Botany © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.  Let’s go back to our original question: “What does this have to do with botany?” Again, the answer is everything. Plants © Jones changed & Bartlett the climate of Earth LLC Learning, such that we can now live on it.© Jones & Bartlett Learning, LLC Plants also produce NOT FOR SALE OR DISTRIBUTION the oxygen we breathe and the food we eat.NOT FOR SALE OR DISTRIBUTION We get cloth, paper, lumber, and chemicals from plants, and plants are important to us spiritually because of their beauty. As you study the following pages, think of the many ways in which plant biology affects our own biology. And think of other organisms; we©share Jones &surface Earth’s Bartlett not Learning, only with LLC © Jones & Bartlett Learning, LL plants but also with all NOTother animals, fungi, and microbes. FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT All our biologies affect those of all other organisms, as we are all interconnected and interdependent. ❚❚ Plants © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FIGURE 1-2 Conifers, like this spruce (Picea), produce seeds in cones; the conifers, NOT Botany FOR is the SALEstudy scientific OR of DISTRIBUTION plants. This definition together with theNOT floweringFOR SALE plants and a few otherOR groups,DISTRIBUTION are known as seed plants. requires an understanding of the concepts “plants” and “scientific study.” It may surprise you to learn that it is diffi- cult to define precisely what a plant is. Plants have so many types and variations that a simple definition has many excep- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC tions, and a definition that includes all plants and excludes NOT FORallSALE ORmay nonplants DISTRIBUTION be too complicated to be useful. Also,NOT FOR SALE OR DISTRIBUTION biologists do not agree about whether certain organisms— particularly algae—are indeed plants. Rather than memoriz- ing a terse definition, more is gained by understanding what plants are, what the exceptional or exotic cases are, and why © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LL botanists disagree about certain organisms. Your present concept NOT FORisSALE of plants probablyORquiteDISTRIBUTION accu- NOT FOR SALE OR DISTRIBUT rate: Most plants have green leaves, stems, roots, and flowers (FIGURE 1-1), but you can think of exceptions immediately. Conifers such as pine, spruce, and fir have cones rather than flowers (FIGURE 1-2), and many cacti and succulents do not © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC appear to have leaves. Both conifers and succulents, however, NOT FOR are obviously plantsSALE OR closely because they DISTRIBUTION resemble organisms NOT FOR SALE OR DISTRIBUTION FIGURE 1-3 Ferns have several features in common with flowering plants; they have that unquestionably are plants. Similarly, ferns and mosses leaves, stems, and roots; however, they never produce seeds, and they have neither (FIGURES 1-3 and 1-4) are easily recognized as plants. Fungi, flowers nor wood. such as mushrooms (FIGURE 1-5) and puffballs, were included in the plant kingdom because they are immobile and produce © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LL NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 1-4 Of all terrestrial plants, mosses have the least in common with flowering FIGURE 1-1 This evening primrose (Oenothera) is obviously a flowering plant. It has a plants. They have structures called “leaves” and “stems,” but these are not the same as © Jones & shortBartlett Learning, stem and numerous simple leaves; itsLLC extensive root system is not visible here. © Jones & plants. in flowering Bartlett They haveLearning, no roots at all. LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Plants 3 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LL NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT © Jones (A) & Bartlett Learning, LLC (B) © Jones & Bartlett Learning, LLC Courtesy of C. Mims, University of Georgia NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 1-5 Fungi such as (A) mushrooms and (B) brackets are not considered to be plants. They are never green and cannot obtain their energy from sunlight. Also, their tissues and physiology are quite different from those of plants. Fungi are important to plants, however, because many fungi break down dead material in the soil such as fallen leaves and rotting tree trunks; as the fungi cause these materials to rot, they release minerals and enrich the soil. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION spores, which function somewhat like seeds; however, biol- solves nothing; the important thing is to understand the con- ogists no longer consider fungi to be plants because recent cepts involved and why disagreement exists (TABLE 1-1). observations show that fungi differ from plants in many All plants have a scientific name. Each name consists of basic biochemical and genetic © Jonesrespects. & Bartlett Learning, LLCtwo words: a genus (pronounced GEE nus)&name © Jones and a spe- Bartlett Learning, LL Algae are more problematical. One group, the green cific epithet. For example, the genus Prunus has several species NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT algae (FIGURE 1-6), is similar to plants in biochemistry and with edible fruits, and they are distinguished by their species cell structure, but it also has many significant differences. epithet: Cherries are Prunus avium, peaches are Prunus per- Some botanists conclude that it is more useful to include sica, and apricots are Prunus armeniaca. The name of cher- green algae with plants; others exclude them, pointing out ries is not just “avium,” it is both words: Prunus avium. In the that some green algae © Jones have more & Bartlett in common LLC Learning, with the sea- scientific names © Jonesof plants, & the genus name Bartlett is always LLC Learning, capital- weeds known as red algae and brown algae (FIGURE 1-7). ized but the species epithet is not (it is not Prunus Avium). NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Arbitrarily declaring that green algae are or are not plants Both words are italicized or underlined. Closely related genera © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LL NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 1-6 These green algae do not look much like plants, but many aspects of © Mateusz Sciborski/ShutterStock, Inc. their biochemistry and cellular organization are very similar to those of plants. Some FIGURE 1-7 These brown algae (Fucus), commonly called kelp, have very plant-like © Jones & greenBartlett algae were theLearning, LLC ancestors of land plants; although not considered to be true © Jones bodies as& Bartlett a result Learning, of convergent evolution: they areLLC not true plants. Their biochemistry, plants, they are obviously NOT FOR SALE OR DISTRIBUTION closely related to plants. NOT genetics, FORanatomy,SALE OR DISTRIBUTION and reproduction differ greatly from those of plants. 4 Chapter 1: Introduction to Plants and Botany © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.  They sought to develop logical explanations for simple obser- TABLE 1-1 The Three Domains of Organisms vations and then followed the logic as far as possible. An Prokaryotes example © Jones is the philosophical & Bartlett Learning, postulation LLC of atoms by Dem- © Jones & Domain Bartlett Archaea Learning, LLC NOT FOR SALE OR(including DISTRIBUTION ocritus around 400 NOT FOR SALE OR DISTRIBUTION bce (before the common era). From the Domain Bacteria cyanobacteria) observation that all objects could be cut or broken into two Eukaryotes smaller objects, it follows logically that the two pieces can Domain Eukarya Protista: single-cell organisms (protozoans, algae); multicellular algae each be subdivided again into two more, and so on. Finally, Kingdom Myceteae: fungi such as mushrooms, puffballs, bread mold some size must be reached at which further subdivision is Kingdom Animalia: animals© Jones & Bartlett Learning, LLC not possible; objects of that size © Jones are atoms.&But Bartlett there wasLearning, no LL Kingdom Plantae: plants NOT FOR SALE OR DISTRIBUTION 1 proof, no experiment to determine if that was actually NOT FOR SALE OR DISTRIBUT valid. Division Bryophyta: mosses Democritus could have been wrong: For all anyone knew, Division Pteridophyta: ferns it might have been possible to continue dividing pieces for- Division Coniferophyta: conifers ever, infinitely. Speculative philosophy did not involve veri- Division Magnoliophyta:2 flowering plants fication; philosophical predictions were made, but no actual 1 Within© Jones kingdom & Bartlett Plantae, many botanists recognizeLearning, LLC about 17 divisions; only the four most experiment© or Jones observation & Bartlett was performed Learning, LLC to see if they were familiar are listed here. Many botanists NOT FOR SALE OR DISTRIBUTION conclude that algae should be included in kingdom correct. A speculation is a statement NOT FOR SALE OR DISTRIBUTION that cannot be proved Plantae. or disproved (e.g., “If Elvis were still alive, he would still be 2 Some people use the term Angiospermophyta. performing in Las Vegas.”). A problem with this method is that often several alternative conclusions are equally plausible are grouped together into families; in botany, family names logically; only experimentation reveals which is actually true. © Jones & Bartlett Learning, LLC are always capitalized and always end in “-aceae” (pronounced © Jones & Bartlett Starting before Learning, the 1400s, a LLC new method, called the NOT FORasSALE if you are OR spelling scientific the word “ace”: AY see ee). Prunus is inNOT FOR SALE OR DISTRIBUTION DISTRIBUTION method, slowly began to develop. Several funda- the rose family Rosaceae (pronounced rose AY see ee), along mental tenets were established: with roses (Rosa), apples (Malus), strawberries (Fragaria), and many others. A very few families have old, alternative endings, 1. Source of information. All accepted information can be but those are rarely used. For example, the modern name for derived only from carefully documented and controlled © Jones the mustard family is Brassicaceae (with the “-aceae” ending);& Bartlett Learning, LLC observations or experiments. © JonesClaims&emanating Bartlettfrom Learning, LL the old family name, Cruciferae, NOT FOR is almost SALE neverOR encountered DISTRIBUTION priests or prophets—or scientists—cannot NOT FOR SALE OR DISTRIBUTbe accepted except in older publications. For animals, family names end in automatically; they must be subjected to verification “-ae.” We humans are Homo sapiens in the family Hominidae; and proof. For example, for hundreds of years, medicine other members of our family are chimpanzees (Pan), gorillas was taught using a text called Materia Medica written (Gorilla), and orangutans (Pongo). by Galen, a Roman physician who lived in the second © Jones & Bartlett Learning, LLC century©ce. Jones (common & Bartlett era = ad). Learning, In the earlyLLC 1500s, NOT FOR SALE OR DISTRIBUTION Andreas Vesalius began dissecting NOT FOR SALE OR DISTRIBUTION human corpses and ❚❚ Scientific Method noticed that in many cases Galen had been mistaken. Vesalius promoted the idea that observation of the The concept of a scientific study can be understood by world itself was more accurate than accepting undocu- examining earlier approaches to studying nature. Until the mented claims, even if the claims had been made by an 15th century, © Jones & Bartlett Learning, LLC several methods for analyzing and explaining © Jonesextremely & Bartlett famous, respected person. Learning, LLC the universe NOT FOR SALE OR DISTRIBUTION and its phenomena were used, with religion 2. Phenomena that NOT FOR SALE OR DISTRIBUTION can be studied. Only tangible phenom- and speculative philosophy being especially important. In ena and objects are studied, such as heat, plants, min- religious methods, the universe is assumed to either be cre- erals, and weather. We cannot see or feel magnetism or ated by or contain deities. The important feature is that the neutrons, but we can construct instruments that detect actions of gods cannot be studied: They are either hidden or them reliably. In contrast, we do not see or feel ghosts, capricious, changing from day to day and altering natural © Jones & Bartlett Learning, LLCand no instrument has ever detected & © Jones ghosts reliably: Bartlett If Learning, LL phenomena. Agricultural studies would NOT FOR SALE OR DISTRIBUTION be useless because ghosts do exist, they must be intangible and NOT FOR SALE OR DISTRIBUT cannot be some years crops might flourish or fail because of weather studied by the scientific method. Anything that cannot or disease, but in other years, crop failure might be due to be observed cannot be studied. a god’s intervention (a miracle) to reward or punish people. 3. Constancy and universality. Physical forces that control the There would be no reason to expect consistent results from world are constant through time and are the same every- experiments. In a religious © Jones & Bartlett Learning, LLC system, much of the knowledge of where.© Water Joneshas always been and always & Bartlett will be composed Learning, LLC the world comes as a NOT FOR SALE OR DISTRIBUTIONrevelation from the deity rather than by of hydrogen and oxygen; gravity NOT FOR SALE OR DISTRIBUTION is the same now as it has observation and study of the world. A fundamental principle been in the past. The world itself changes—mountains of all religions is faith: People must believe in the god without erode, rivers change course, plants evolve—but the forces physical proof of its existence or actions. remain the same. Experiments done at one time and place Speculative philosophy reached its greatest development should give the same results if they are carefully repeated with the ancient © Jones & Bartlett Learning, LLC Greek philosophers. Basically, their method © Jonesat&a Bartlett different time and place. Constancy Learning, LLC and universal- of analyzing NOT FOR SALE OR DISTRIBUTION the world involved thinking about it logically. ity allow us to NOT FOR SALE OR DISTRIBUTIONplan future experiments and predict what Scientific Method 5 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.  the outcome should be: If we do the experiment and do the Middle Ages observed that plants never occur in dark caves not get the predicted outcome, it must be that our the- and grow poorly indoors where light is dim. They hypothesized ory was incorrect, © Jones & Bartlett Learning, LLC not that the fundamental forces of the that plants © Jones need lightLearning, & Bartlett to grow. ThisLLC can be formally stated as world have suddenly NOT FOR SALE OR DISTRIBUTION changed. This prevents people from a pair of simple alternative NOT FOR SALE OR DISTRIBUTION hypotheses: (1) Plants need light explaining things as miracles or the intervention of evil to grow, and (2) plants do not need light to grow. The exper- spirits. For example, if someone claims that a new drug imental testing may involve the comparison of several plants cures a particular disease, we can check that by testing outdoors, some in light and others heavily shaded, or it may the same drug against that disease. If it does not work, involve several plants indoors, some in the normal gloom and the first person may©have Jones & Bartlett Learning, LLC (1) made an innocent mistake, others illuminated by a window © Jones & Bartlett or a skylight. Learning, LL Such experi- (2) tested the drugNOT on people who would have FOR SALE OR DISTRIBUTION gotten ments give results consistent with hypothesis NOT FOR SALE 1; hypothesis 2 OR DISTRIBUT better anyway, or (3) been committing fraud; however, would be rejected. we do not have to worry that the difference in the two A hypothesis must be tested in various ways. It must be experiments is due to the fundamental laws of chemistry consistent with further observations and experiments, and it and physics having changed or that the first experiment’s must be able to predict the results of future experiments: One © Jones & Bartlett Learning, LLC outcome was altered by benevolent spirits and the sec- © values of the greatest Jones of a& Bartlett hypothesis Learning, or theory LLC is its power as a ond by evil spirits. NOT FOR SALE OR DISTRIBUTION predictive model. If its predictions NOT FOR SALE OR DISTRIBUTION are accurate, they support 4. Basis. The fundamental basis of the scientific method the hypothesis; if its predictions are inaccurate, they prove is skepticism, the principle of never being certain of a that the hypothesis is incorrect. In this case, the hypothesis conclusion, of always being willing to consider new predicts that environments with little or no light will have few evidence. No matter how much evidence there is for or or no plants. Observations are consistent with these predic- © Jones & Bartlett Learning, against a theory, it does noLLCharm to keep a bit of doubt in© Jones tions. & In aBartlett Learning, heavy ­forest, shade is dense LLCat ground level, and few our minds and NOT FOR SALE OR DISTRIBUTION to be willing to consider more evidence. NOT FOR SALE OR DISTRIBUTIONas light penetrates plants grow there (FIGURE 1-8). Similarly, For example, there is a tremendous amount of evidence the ocean, it is absorbed by water until at great depth all light supporting the theory that all plants are composed of has been absorbed; no plants or algae grow below that depth. cells, and there is no known evidence against it. All of If a hypothesis continues to match observations, we our research, all of our teaching assumes that plants have greater confidence that it is correct, and it may come indeed are composed © Jones & the of cells, but Bartlett concept Learning, of skepti- LLC to be called a theory. Occasionally,© Jones & Bartlett a hypothesis does Learning, not LL cism requires that ifNOT new, contrary evidence is presented, FOR SALE OR DISTRIBUTION match an observation; that may mean either that NOT FOR SALE OR DISTRIBUT the hypoth- we must be willing to change our minds. As a further esis must be altered somewhat or that the entire hypothesis example, consider people who have been convicted of has been wrong. For instance, plants such as Indian pipe or crimes and then later—often years later—DNA-based Conopholis (FIGURE 1-9) grow the same with or without light; evidence indicates that they are innocent: Skepticism is they do not need light for growth. These are parasitic plants © willingness the Jones &toBartlett consider newLearning, evidence. LLC that obtain©their Jones energy & byBartlett drawingLearning, nutrients from LLChost NOT FOR SALE OR DISTRIBUTION plants. Thus, our hypothesis needs NOT FOR SALE OR DISTRIBUTION only minor modification: Scientific studies take many forms, but basically, they begin All plants except parasitic ones need sunlight for growth. It with a series of observations, followed by a period of exper- remains a reasonably accurate predictive model. imentation mixed with further observation and analysis. At Note the four principles of the scientific method here. some point, a hypothesis, or model, is constructed to account First, the hypothesis is based on observations and can be for Bartlett © Jones & the observations: A hypothesis Learning, LLC(unlike a speculation) must© Jones tested& with experiments; Bartlett we do notLLC Learning, accept it simply because make predictions that can be tested. For example, scientists in some famous scientist declared it to be true. Second, sunlight NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LL NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (A) Courtesy of R. Fulginiti, University of Texas, Austin (B) Courtesy of R. Fulginiti, University of Texas, Austin © Jones & Bartlett FIGURE Learning, 1-8 (A) This LLC aspen forest in Michigan © Jones does not have a dense canopy, but it intercepts & Bartlett so much light Learning, that few plants survive LLC in the shade. The herb is the bracken fern NOT FORPteridium SALE OR(B)DISTRIBUTION aquilinum. NOT Near the aspen forest is an open area with more light; herb growth, FOR in this SALE case a sedge, is muchOR DISTRIBUTION more abundant. 6 Chapter 1: Introduction to Plants and Botany © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.  ❚❚ Areas Where the © Jones & Bartlett Learning, LLC © JonesScientific Method & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Is Inappropriate Certain concepts exist for which the scientific method is inap­ propriate. We all believe that it is not right to wantonly kill each © Jones & Bartlett Learning, LLC other, that racism and sexism © areJones bad, and &thatBartlett things such as Learning, LL morality and ethics exist; however, both morality and ethics NOT FOR SALE OR DISTRIBUTION NOT FOR SALE have no chemical composition, no mass, no electromagnetic OR DISTRIBUT spectrum—they are not tangible and thus cannot be studied by the scientific method. Science can study, measure, analyze, and describe the factors that cause people to kill each other or © Jones & Bartlett Learning, LLC to be racist ©or Jones sexist, and&itBartlett can predictLearning, the outcome of LLCthese FIGURE 1-9 The yellowish flowers pushing out of the pine needle litter constitute actions. Science, however, cannot say whether such actions are NOT almost the FOR entire plant body SALE OR of this parasitic plant,DISTRIBUTION Conopholis mexicana. It is attached NOT FOR SALE OR DISTRIBUTION right or wrong, moral or immoral. Consider euthanasia: Many to the roots of nearby trees and draws nutrients from them. Like fungi, it cannot obtain types of incurable cancer cause terrible pain and suffering in its energy from sunlight, but so many other aspects of its anatomy and physiology are their final stages, which may last for months. We have drugs like those of ordinary plants that we have no difficulty in recognizing that this is a true that can arrest breathing so that a person dies painlessly and plant, not a fungus. © Jones & Bartlett Learning, LLC peacefully. © Jones Science developed & Bartlett Learning, the drugs LLCand can tell us the met- abolic effects of using them, but it cannot tell us whether it is NOT FOR SALE OR DISTRIBUTION NOT right FOR SALE OR DISTRIBUTION to use them to help a person die and avoid pain. Biological and plant growth are tangible phenomena that we can either see directly or measure with instruments. Third, if we repeat advances have made us capable of ­surrogate motherhood, of the experiment anytime or anywhere, we expect to get the detecting fetal birth defects early enough to allow a medically same results. Fourth, we interpret the evidence as supporting safe abortion, and of producing insecticides that protect crops © Jones & the hypothesis, but we keep an open mind and are willing to Bartlett Learning, but pollute the environment.©These LLC Jonesadvances have made & Bartlett it Learning, LL consider new data or a new hypothesis. more important than ever for us to have well-developed ethical NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT In former times, if a theory had sufficient support, it was philosophy for assessing the appropriateness of various actions. referred to as a “law,” such as the laws of thermodynamics or the law that for every action there is an equal and oppo- site reaction. Physicists occasionally still do this but biolo- © Jones gists never use the&term Bartlett Learning, “law.” Even though weLLC have tens of ❚❚ Using Concepts to © Jones & Bartlett Learning, LLC thousands NOTofFOR observations SALEthat OR plants are composed of cells, DISTRIBUTION Understand Plants NOT FOR SALE OR DISTRIBUTION there is no “law that all plants are composed of cells,” instead we just treat this as a well-supported theory. No biologist The growth, reproduction, and death of plants—indeed, all expects that there will be a discovery that shows that plants aspects of their lives—are governed by a small number of are not actually made up of cells, but we simply do not ever basic principles. Each chapter in this text opens with a sec- © Jones & useBartlett Learning, the term “law. ” LLC tion called © Jones “Concepts, & Bartlett ” which discusses Learning, LLC the principles most Many ORpeople relevant to the attempt to discredit the theory of evolutionNOT FOR SALE OR DISTRIBUTION topics in that particular chapter. Here in this NOT FOR SALE DISTRIBUTION chapter and at the beginning of your study of botany and by natural selection by saying that it is merely a theory of evolution, not a law of evolution; these people do not realize plants, I want to introduce you briefly to some of these princi- that their argument is nonsensical. ples and to encourage you to use them as you read and think The concept of intelligent design has recently been about plants. These concepts will make plant biology more proposed to explain many © Jones complex& Bartlett Its phenomena. Learning, funda- easily LLC understood—the numerous facts, figures, names, © Jones & Bartlett Learning, and LL mental concept is thatNOT many FORstructures and OR metabolisms data will be less overwhelming when you realize that they all SALE DISTRIBUTION NOT FOR SALE fit into the patterns governed by a few fundamental concepts. OR DISTRIBUT are too complicated to have resulted from evolution and natural selection. Instead, they must have been created by 1. Plant metabolism is based on the principles of chemistry some sort of intelligent force or being. This may or may not and physics. Weeds may seem to appear from nothing as be true, but this does not help us to analyze and under- if by magic; however, that is never true—they grow from stand©theJones & Bartlett world; instead, Learning, it is used as an answerLLCin itself that seeds. © AllJones & Bartlett the principles you learnLearning, LLCor in your chemistry prevents NOT further FOR study. SALEPhotosynthesis is certainly complex, OR DISTRIBUTION physicsNOT classesFORare completely SALE OR validDISTRIBUTION for plants. and it may have been designed by some intelligent being; 2. Plants must have a means of storing and using informa- however, believing that does not help us to understand tion. After a seed germinates, it grows and develops into a photosynthesis at all, and it does not help us to plan future plant, becoming larger and more complex; then it repro- experiments. In contrast, the scientific method is a means duces. The plant is taking in energy and chemical com- © Jones & Bartlett through which Learning, LLC even the most subtle© Jonespounds we are discovering & Bartlett Learning, and transforming themLLCinto the organic chemical NOT FORdetails SALE of photosynthesis. OR DISTRIBUTION NOT FOR compounds SALE OR it usesDISTRIBUTION to build more of itself. This requires a Using Concepts to Understand Plants 7 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.  complex, carefully controlled metabolism, and there must be a mechanism for storing and using the information that regulates © Jones & Bartlett that metabolism. Learning, LLC As you may already know,© Jones & Bartlett Learning, LLC genes are the primary NOT FOR SALE OR DISTRIBUTION means of storing this information.NOT FOR SALE OR DISTRIBUTION 3. Plants reproduce, passing their genes and information on to their descendants. Because an individual obtains its genes from its parents, the information it uses to con- trol its metabolism is similar to the information its par- ent had used; thus,© Jonesand offspring &parents Bartlett Learning, resemble each LLC (A) © Jones & Bartlett Learning, LL other. For ex­ample,NOT a bean seed contains genes FOR SALE OR DISTRIBUTION whose NOT FOR SALE OR DISTRIBUT information guides the seed’s metabolism into con- structing a new bean plant, but a tomato seed grows into a tomato plant because it received different genes and information from its parents (FIGURE 1-10). © Jones 4. Genes, and the& Bartlett informationLearning, they contain,LLC change. As © Jones & Bartlett Learning, LLC plants make copies of their NOT FOR SALE OR DISTRIBUTION genes during reproduction, NOT FOR SALE OR DISTRIBUTION accidental changes (mutations) occasionally occur, and this causes the affected gene and its information to change. This is quite rare, and most genes (and infor- mation) are passed unaltered from parents to offspring; © Jones & Bartlett however, asLearning, mutations occurLLCand change a gene’s infor-© Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONnew information suchNOT FOR SALE OR DISTRIBUTION mation, they basically generate that the plant that grows and develops under the control (B) (C) of the mutated gene may be slightly (or significantly) different from its parents. Thus, over time, a gradual evolution occurs in the genes, information, and biology © Jones of plants. Consequently, & Bartlett in a large populationLearning, of many LLC © Jones & Bartlett Learning, LL individuals of a species, some variation exists; NOT FOR SALE OR DISTRIBUTION the indi- NOT FOR SALE OR DISTRIBUT viduals are not identical (FIGURE 1-11). © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (D) (E) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LL NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUT © Jones & Bartlett Learning, LLC © Jones (F) & Bartlett(G) Learning, LLC NOT FOR SALE OR DISTRIBUTION FIGURE 1-11 (A) A plant produces numerous offspring,DISTRIBUTION NOT FOR SALE OR many of which resemble it strongly (B). Mutations may occur that cause, for instance, leaves to be malformed and poorly shaped for photosynthesis (C); most or all these mutants die and do not reproduce. The normal plants continue to reproduce (B) and (D), but another mutation may occur that causes the leaves to be larger and more efficient at photosynthesis (E). © Jones & Bartlett FIGURE 1-10 This Learning, LLC bean seed is developing into a bean plant, guided by genetic © Jones These may &grow Bartlett Learning, and reproduce LLC so well that they crowd out the original parental types, NOT FORinformation SALEit inherited OR DISTRIBUTION from its parents. NOT and FOR SALE the plant populationOR contains only the type with large leaves (F) and (G). finallyDISTRIBUTION 8 Chapter 1: Introduction to Plants and Botany © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.  Plants and People © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION BOX 1-1 Plants and People, Including Students Plants and people affect each other. The most obvious per- warming, but the possibility exists that global warming is haps are the ways that © Jones people & from benefit Bartlett plants:Learning, They are LLC preventing the occurrence of © Jones another & Bartlett Learning, LL ice age. the sources of our food,NOT wood,FORpaper,SALE OR fibers, and DISTRIBUTION medicines. NOT FOR Desertification is the conversion SALEforest of ordinary OR DISTRIBUT or It is difficult to excite students by listing the world produc- grassland to desert. Accurate measurements are difficult, but tion of wheat and lumber in metric tons, but just consider it appears that deserts may be spreading as people cut shrubs what your life would be like without chocolate, coffee, tea, and trees for firewood and allow goats to eat remaining veg- sugar, vanilla, cinnamon, pepper, strawberries, mahogany, etation. Once an area has been converted to desert, its soil is ebony,©cotton, Jones & Bartlett linen, Learning, roses, orchids, or the paper LLC that exami- © Jones rapidly eroded, & Bartlett making recovery Learning, difficult. SomethingLLCas sim- nationsNOT FOR on. are written SALE OR DISTRIBUTION The oxygen we breathe comes entirely ple as cheapNOT solar FOR cookersSALE OR DISTRIBUTION might prevent the Sahara desert from plants. Plants affect each of us every day, not simply by from spreading farther across Africa. keeping us alive but also by providing wonderful sights, tex- Habitat loss results when an area is changed so much tures, and fragrances that enrich our existence. that a particular species can no longer survive in the area. However, plants and people affect each other in ways Significant causes are the construction of highways, housing © Jones & thatBartlett Learning, are not readily apparentLLCin our day-to-day lives. Listed© Jones & Bartlett subdivisions, Learning, and shopping mallsLLC with enormous parking NOT FORhere SALE ORimportant are a few DISTRIBUTION topics you should be aware of. ThinkNOT lots; FOR SALE these ORalmost eliminate DISTRIBUTION all species from an area, but hab- about their importance and how you—as an actual biological itats are also lost by logging, farming, mining, damming riv- organism—interact with the other organisms on this planet. ers, and spilling toxic chemicals. As habitat is lost, plants or Biotechnology is a set of laboratory techniques that allow animals must try to survive on the smaller remaining habitat. us