© 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, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOTCHAPTER FOR SALE OR DISTRIBUTION 1
© Jones & Bartlett Learning, LLC © Jones & BartlettOUTLINE Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Introduction to • Concepts • Plants Plants and Botany • Scientific Method © Jones & Bartlett Learning, LLC • Areas Where© Jones the Scientific & Bartlett Method Learning, LLC NOT FOR SALE OR DISTRIBUTION Is InappropriateNOT FOR SALE OR DISTRIBUTION 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 • Describe© Jones the difficulty & Bartlett in creatingLearning, a singular LLC definition of a plant. © Jones• Plants & BartlettVersus the Learning, Study of Plants LLC • ListNOT four fundamentalFOR SALE tenets OR DISTRIBUTIONof the scientific method. NOT BoxFOR 1-1 PlantsSALE and OR People: DISTRIBUTION 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 &• OrderBartlett the process Learning, of evolution LLC from early prokaryote© to Jones plant. & BartlettBox Learning, 1-3 Plants and LLC People: Algae and NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION • Provide two examples of plant adaptations. Global Warming • Explain the difference between observation and interpretation.
© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Chapter Opener Image: People and animals must Did You Know? have oxygen to live. Without oxygen, we would die of asphyxiation. The plants here are photosynthesizing • Early 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© Jones as early & Bartlettas 36,000 yearsLearning, ago. LLC © Jonesslopes. & Without Bartlett the trees, Learning,rain would wash all theLLC soil • Vanilla,NOT chocolate, FOR SALE coffee, OR tea, DISTRIBUTION cinnamon, and mint are all made NOT FORaway leaving SALE just bare OR rock andDISTRIBUTION 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 & Bartlett Learning, LLC © Jones & Bartlett Learning,Worthington Glacier, LLC Alaska. • Science and the scientific method are a simple set of accepted rules NOT FOR SALEabout the OR ways DISTRIBUTION in which evidence can be gathered and NOTprocessed. FOR SALE OR DISTRIBUTION 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 is becoming Learning, hotter, floodin LLC g is more frequent, and© Jonesrock) &comes Bartlett upward Learning, at mid-ocean LLC ridges between the giant NOT FORweather SALE is morORe DISTRIBUTIONviolent because we burn coal, oil, and otherNOT tectonicFOR SALE plates tha ORt car DISTRIBUTIONry 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- and water give off infrar©ed Jones radiation & back Bartlett out towa Learning,rd space, LLCnoes were very active and added© Jones carbon dioxide& Bartlett faster thaLearning,n LLC but greenhouse gases NOTabsorb FORinfrar edSALE light ORand heaDISTRIBUTIONt the photosynthesis could removeNOT it, cau singFOR Ear SALEth to hea ORt up. DISTRIBUTIONAt 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 rains,© causing Jones floodin & Bartlettg throughout Learning, the world. LLC The warmer warm, rains© were Jones also hea & vyBartlett (because Learning,of the warm oceaLLCns), air alsoNOT causes FOR snow SALE and ice onOR mountain DISTRIBUTION tops to melt faster, so plants grewNOT fast FORer and SALEmore abun ORdantly, 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- © Jones &global Bartlett warming, Learning, also known LLCas global climate change. © Jonestory. Plants& Bartlett have tak enLearning, so much carb LLCon dioxide out of the air What does this have to do with botany? Everything. Plants there is almost none to trap the sun’s heat. We are actually NOT FORin SALE the sun ORphotosynthesize; DISTRIBUTION that is, they take carbon dioxideNOT inFOR an ice SALE age righ ORt now 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.Jones As plants & phoBartletttosynthesize, Learning, they LLCalmost all mountains). Is it bad© thaJonest Earth & is unusBartlettually cool? Learning, LLC remove carbon dioxide from the air and lock it into their bod- Should we be burning even more petroleum and coal to heat ies, helping to keep EarthNOT cool FORand count SALEeracting OR the DISTRIBUTION warm- it up? NOT FOR SALE OR DISTRIBUTION 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© Jonesbalance betw & Bartletteen the additio Learning,n of atmospheric LLC carbon plants evolved:© Jones Wheat, rye& ,Bartlett barley, and Learning, corn are gras LLCses that dioxide by us and its removal by plants is affected by several flourish under cool, dry conditions. Grasses grow on open, factorsNOT that areFOR easy SALEto unders ORtand. DISTRIBUTION All animals, fungi, bacte- treeless plains,NOT but FOR when EarSALEth is warm OR DISTRIBUTIONmost 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 &carbon Bartlett dioxide Learning, to the atmosphere LLC for billions of years. The© Joneswalk upright& Bartlett on the groLearning,und, freeing LLC our forelimbs (our arms) NOT FORreal SALE problem OR began DISTRIBUTION when our ancestors discovered fire:NOT suchFOR that SALE 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© Joneswas adding & it.Bartlett Learning, LLCMore recently, we people© beganJones to cul& tivateBartlett our ownLearning, LLC Photosynthesis origNOTinated FOR2.8 bil lionSALE years OR ago , DISTRIBUTIONand the food. Agriculture is new, havNOTing sepa FORrate, indepenSALEdent OR ori DISTRIBUTION- 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 does ©that Jones mean ther& Bartlette was mor eLearning, carbon dioxide LLC in the air spread across© Jonesmore of the & lanBartlettd, and som Learning,e humans made LLC the in theNOT past? FORAnd, if SALE so, was OREarth DISTRIBUTION warmer in the past? The journey fromNOT Asia FOR to the SALEAmericas OR at tha DISTRIBUTIONt 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 &periods Bartlett of time. Learning, LLC © Joneswith art,& Bartlettwriting, 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 clima Learning,te of Earth LLCsuch that we can now live on it.© Jones & Bartlett Learning, LLC NOT FORPlants SALE also produceOR 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© sha Jonesre Earth’s & surfaceBartlett not Learning,only with LLC © Jones & Bartlett Learning, LLC plants but also with all NOTother animaFORls, SALE fungi, andOR microb DISTRIBUTIONes. NOT FOR SALE OR DISTRIBUTION 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, BotanyNOT is theFOR scientific SALE stud ORy ofDISTRIBUTION plants. This definition together with theNOT flowering FOR plants andSALE a few other OR 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 © Jones &types Bartlett and variations Learning, that a simple LLC definition has many excep-© Jones & Bartlett Learning, LLC NOT FORtions, SALE and ORa definitio DISTRIBUTIONn that includes all plants and excludesNOT FOR SALE OR DISTRIBUTION all nonplants may be too complicated to be useful. Also, 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 except© Jonesional or exot & Bartlettic cases are Learning,, and why LLC © Jones & Bartlett Learning, LLC botanists disagree aboutNOT certain FOR organisms. SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Your present concept of plants is probably quite accu- 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© (JonesFIGURE 1-2 &), Bartlettand many cactLearning,i and succu LLClents do not © Jones & Bartlett Learning, LLC appearNOT to have FOR leaves. SALE Both conifer OR DISTRIBUTIONs and succulents, however, NOT FOR SALE OR DISTRIBUTION are obviously plants because they closely resemble organisms 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 © Jones &in theBartlett plant king Learning,dom because LLC they are immobile and produce© Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
© 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 &short Bartlett stem and numerous Learning, simple leaves; itsLLC extensive root system is not visible here. © Jonesin flowering & Bartlettplants. They have Learning, 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, LLC (A) (B) 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© Jones respects. & Bartlett Learning, LLCtwo words: a genus (pronounced© Jones GEE nus) & nam Bartlette and a speLearning,- LLC Algae are more proNOTblematical. FOR OneSALE gro up,OR the DISTRIBUTION green cific epithet. For example, the genuNOTs Prunus FOR has SALE several OR species DISTRIBUTION 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© Jones green algae& Bartlett have mor Learning,e in common LLCwith the sea- scientific names© Jones of plants, & theBartlett genus nam Learning,e is always LLCcapital- weedsNOT known FOR as red SALE algae ORand broDISTRIBUTIONwn algae (FIGURE 1-7). ized but theNOT species FOR epithet SALE is not OR(it is DISTRIBUTIONnot Prunus Avium). Arbitrarily declaring that green algae are or are not plants Both words are italicized or underlined. Closely related genera
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 &green Bartlett algae were the Learning, ancestors of land plants; LLC although not considered to be true © Jonesbodies as & a result Bartlett of convergent Learning, evolution: they are LLC not true plants. Their biochemistry, NOT FORplants, SALE they are OR obviously DISTRIBUTION closely related to plants. NOT genetics,FOR anatomy, SALE and reproductionOR DISTRIBUTION differ greatly from those of plants. 4 Chapter 1: Introduction to Plants and Botany
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. TABLE 1-1 The Three Domains of Organisms They sought to develop logical explanations for simple obser- vations and then followed the logic as far as possible. An © Jones &Prokaryotes Bartlett Learning, LLC © Jonesexample & Bartlettis the philos Learning,ophical post ulationLLC of atoms by Dem- Domain Archaea ocritus around 400 bce (before the common era). From the NOT FOR SALEDomain Bacteria OR (including DISTRIBUTION cyanobacteria) NOT FOR SALE OR DISTRIBUTION observation that all objects could be cut or broken into two Eukaryotes Domain Eukarya smaller objects, it follows logically that the two pieces can 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, LLCnot possible; objects of that size© Jonesare atoms. & But Bartlett there was Learning, no LLC Kingdom Plantae:1 plants NOT FOR SALE OR DISTRIBUTIONproof, no experiment to determinNOTe if FOR that was SALE actually OR valid DISTRIBUTION. 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- 2 Division Magnoliophyta: flowering plants fication; philosophical predictions were made, but no actual 1Within© kingdom Jones Plantae, many& Bartlett botanists recognize Learning, about 17 divisions; only LLC the four most experiment© or Jonesobservation & Bartlettwas performed Learning, to see if the LLCy were familiarNOT are listed FOR here. Many SALE botanists conclude OR that DISTRIBUTION algae should be included in kingdom correct. A speculationNOT FOR is aSALE statement OR tha DISTRIBUTIONt cannot be proved Plantae. or disproved (e.g., “If Elvis were still alive, he would still be 2Some 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 &are Bartlett always capitalized Learning, and alwa LLCys end in “-aceae” (pronounced© JonesStarting & Bartlett before Learning,the 1400s, a LLCnew method, called the NOT FORas SALE if you are OR spe DISTRIBUTIONlling the word “ace”: AY see ee). Prunus is inNOT scientificFOR SALE method OR, slowly DISTRIBUTION 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 the mustard family is Bras©sicaceae Jones (wit &h Bartlett the “-aceae” Learning, ending); LLCobservations or experiments.© Jones Claims & eman Bartlettating fro Learning,m LLC the old family name, CruciferaeNOT FOR, is almos SALEt never OR encoun DISTRIBUTIONtered priests or prophets—or scientNOTists—cannot FOR SALE be accepte OR DISTRIBUTIONd 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 early LLC 1500s, NOT FOR SALE OR DISTRIBUTION AndreasNOT Vesalius FOR began SALE dissecting OR DISTRIBUTIONhuman 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 © Jones &15th Bartlett century, sevLearning,eral methods LLC for analyzing and explaining© Jonesextremely & Bartlett famous, Learning, respected person. LLC NOT FORthe SALE universe OR and DISTRIBUTION its phenomena were used, with religionNOT FOR2. Phenomena SALE ORthat canDISTRIBUTION 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 fro©m Jones day to day & Bartlettand altering Learning, natural LLCand no instrument has ever© Jones detected &ghos Bartlettts reliably: Learning, If LLC phenomena. AgriculturalNOT studies FOR wou SALEld be use ORless DISTRIBUTIONbecause ghosts do exist, they musNOTt be inta FORngible SALE and cann ORot beDISTRIBUTION 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.© Jones In a &relig Bartlettious system, Learning, much of the LLC knowledge of where. ©Water Jones has always & Bartlett been and alwa Learning,ys will be comp LLCosed the worldNOT comes FOR as SALEa revelation OR fro DISTRIBUTIONm the deity rather than by of hydrogenNOT and FOR oxygen; SALE grav ityOR is the DISTRIBUTION 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 © Jones &with Bartlett the ancient Learning, Greek philos LLCophers. Basically, their method© Jonesat & a Bartlettdifferent time Learning, and place. ConLLCstancy and universal- NOT FORof SALE analyzing OR the DISTRIBUTION world involved thinking about it logically.NOT FORity SALEallow us toOR pla DISTRIBUTIONn 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 © Jones & Bartlettory was incorrect, Learning, not tha LLCt the fundamental forces of the© Jonesthat plants & Bartlett need light Learning, to grow. This LLC can be formally stated as NOT FOR SALEworld haveOR suddenlyDISTRIBUTION changed. This prevents people fromNOT aFOR pair of SALE simple ORalternative 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© hav Jonese (1) made & Bartlett an innocen Learning,t mistake, LLCothers illuminated by a windo©w Jones or a sky light.& Bartlett Such experi Learning,- LLC (2) tested the drugNOT on peo FORple who SALE would OR hav eDISTRIBUTION gotten ments give results consistent witNOTh hypo FORthesis SALE 1; hypo ORthesis DISTRIBUTION 2 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 outcome© Jones was &alt eredBartlett by bene Learning,volent spirits LLC and the sec- of the greatest© valuesJones of a& hypo Bartlettthesis or theLearning,ory is its pow LLCer as a ondNOT by evilFOR spirits. SALE OR DISTRIBUTION predictive model.NOT IfFOR its pre SALEdictions ORare accurat DISTRIBUTIONe, 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 & Bartlettagainst a theory,Learning, it does noLLC harm to keep a bit of doubt in© Jonestions. &In aBartlett heavy for est, Learning, shade is dense LLC at ground level, and few NOT FOR SALEour minds OR andDISTRIBUTION to be willing to consider more evidence.NOT plantsFOR growSALE ther ORe (FIGURE DISTRIBUTION 1-8). Similarly, as light penetrates 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© Jonesof cells, but & theBartlett concept Learning,of skepti- LLCto be called a theory. Occasionally,© Jones a hypo & thesisBartlett does Learning,not LLC cism requires that ifNOT new, cont FORrary SALE evidence OR is pres DISTRIBUTIONented, match an observation; that mayNOT mea nFOR either SALEthat the hypoOR thDISTRIBUTION- 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 the© willingnessJones & toBartlett consider newLearning, evidence. LLC that obtain© their Jones energ &y byBartlett drawing Learning, nutrients fro LLCm host NOT FOR SALE OR DISTRIBUTION plants. Thus,NOT our hypo FORthesis SALE needs OR only DISTRIBUTIONminor 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 © Jones &for Bartlettthe observations: Learning, A hypothesis LLC (unlike a speculation) mus©t Jonestested & with Bartlett experim ents;Learning, we do not LLC accept it simply because NOT FORmake SALE predictions OR DISTRIBUTION that can be tested. For example, scientists inNOT someFOR famous SALE scient ORist DISTRIBUTION declared it to be true. Second, sunlight
(A) Courtesy of R. Fulginiti, University of Texas, Austin (B) Courtesy of R. Fulginiti, University of Texas, Austin © Jones &FIGURE Bartlett 1-8 (A) This Learning, aspen forest in Michigan LLC does not have a dense canopy, but it intercepts© Jones so much light& Bartlettthat few plants surviveLearning, in the shade. TheLLC herb is the bracken fern NOT FORPteridium SALE aquilinum OR. ( B)DISTRIBUTION Near the aspen forest is an open area with more light; herb growth,NOT in this FOR case a sedge,SALE is much OR more abundant.DISTRIBUTION 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 & Bartlett Learning, Method LLC NOT FOR SALE OR DISTRIBUTION NOT FORIs SALEInappropriate OR DISTRIBUTION 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, LLCother, that racism and sexism ©are Jones bad, and &tha Bartlettt things such Learning, as LLC NOT FOR SALE OR DISTRIBUTIONmorality and ethics exist; howNOTever, bot FORh mora SALElity and OR ethics DISTRIBUTION have no chemical composition, no mass, no electromagnetic 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 Jonessexist, and & it Bartlett can predict Learning, the outcome ofLLC these FIGURENOT 1-9 The FOR yellowish SALEflowers pushing OR out DISTRIBUTION of the pine needle litter constitute actions. Science,NOT how FORever, cannSALEot say OR whet DISTRIBUTIONher such actions are almost the entire plant body of this parasitic plant, Conopholis mexicana. It is attached 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 © Jonespeacefully. & Bartlett Science deve Learning,loped the drugs LLC and can tell us the met- NOT FOR SALE OR DISTRIBUTION NOT abolicFOR effects SALE of usingOR DISTRIBUTIONthem, but it cannot tell us whether it is and plant growth are tangible phenomena that we can either right to use them to help a person die and avoid pain. Biological see directly or measure with instruments. Third, if we repeat advances have made us capable of surr ogate 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 the hypothesis, but we keep© Jones an open & mind Bartlett and are Learning,willing to LLCbut pollute the environment. ©These Jones advan &ces Bartlett have made Learning, it LLC consider new data or a newNOT hypothesis. FOR SALE OR DISTRIBUTIONmore important than ever for usNOT to hav FORe well-developed SALE OR ethica DISTRIBUTIONl 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- ❚❚ Using Concepts to gists never© Jones use the & term Bartlett “law.” Even Learning, though we LLC have tens of © Jones & Bartlett Learning, LLC thousandsNOT of FOR obser vationsSALE tha ORt pla DISTRIBUTIONnts are composed of cells, UnderstandNOT FOR SALE Plants 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 &use Bartlett the term “law.” Learning, LLC © Jonestion called & Bartlett “Concepts,” Learning, which disc LLCusses the principles most NOT FOR SALEMany ORpeople DISTRIBUTION attempt to discredit the theory of evolutionNOT relevantFOR SALE to the top ORics DISTRIBUTIONin that particular chapter. Here in this by natural selection by saying that it is merely a theory of chapter and at the beginning of your study of botany and 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 man©y Jones complex &phen Bartlettomena. ItsLearning, funda- LLCeasily understood—the numer©ous Jones facts, figures, & Bartlett names, Learning,and LLC mental concept is thatNOT many FORstructures SALE and ORmeta DISTRIBUTIONbolisms data will be less overwhelmingNOT when FORyou rea SALElize that ORthey allDISTRIBUTION are too complicated to have resulted from evolution and fit into the patterns governed by a few fundamental concepts. 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© the Jones world; inst& Bartlettead, it is use Learning,d as an answ erLLC in itself that seeds. ©All Jones the prin ciples& Bartlett you lear nLearning, in your chemi LLCstry or preventsNOT further FOR stud SALEy. Pho tosynthesisOR DISTRIBUTION is certainly complex, physicsNOT classes FOR are completely SALE ORvalid DISTRIBUTION 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 &through Bartlett which Learning, we are disco LLCvering even the most subtle© Jonespounds & Bartlett and tran Learning,sforming them LLC into the organic chemical NOT FORdetails SALE of photosynthesis.OR DISTRIBUTION NOT FORcompounds SALE ORit uses DISTRIBUTION 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 © Jones & Bartlettthat regulates Learning, that metabolism. LLC As you may already know,© Jones & Bartlett Learning, LLC NOT FOR SALEgenes areOR the DISTRIBUTION primary 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,© offsp Jonesring and & par Bartlettents resem Learning,ble each LLC (A) © Jones & Bartlett Learning, LLC other. For example,NOT a bea FORn seed SALEcontains ORgenes DISTRIBUTION whose NOT FOR SALE OR DISTRIBUTION 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). 4. Genes,© Jones and the& Bartlettinformation Learning, they contain, LLC change. As © Jones & Bartlett Learning, LLC plantsNOT make FOR copies SALE of their OR genes DISTRIBUTION 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 & Bartletthowever, asLearning, mutations occur LLC and change a gene’s infor-© Jones & Bartlett Learning, LLC NOT FOR SALEmation, OR they DISTRIBUTION basically generate new information suchNOT FOR SALE OR DISTRIBUTION 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 of plants. Consequently,© Jones in a lar &ge Bartlett population Learning, of many LLC © Jones & Bartlett Learning, LLC individuals of a speNOTcies, som FORe vari SALEation exists; OR theDISTRIBUTION indi- NOT FOR SALE OR DISTRIBUTION viduals are not identical (FIGURE 1-11).
© Jones & Bartlett Learning, LLC (F)© Jones & Bartlett(G) Learning, LLC NOT FOR SALE OR DISTRIBUTION FIGURE 1-11 NOT(A) A plant FOR produces SALE numerous offspring, OR DISTRIBUTION 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 &FIGURE Bartlett 1-10 This Learning,bean seed is developing LLC into a bean plant, guided by genetic © JonesThese may & grow Bartlett and reproduce Learning, so well that they crowd LLC out the original parental types, NOT FORinformation SALE it inheritedOR DISTRIBUTION from its parents. NOT andFOR the plant SALE population OR finally DISTRIBUTION contains only the type with large leaves (F) and (G) . 8 Chapter 1: Introduction to Plants and Botany
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & BartlettPlants Learning, and LLC People © 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 ©peo Jonesple benefi &t froBartlettm plants: Learning, They are LLCpreventing the occurrence of ©another Jones ice age.& Bartlett Learning, LLC the sources of our food,NOT wood, FOR paper, SALEfibers, and OR medicin DISTRIBUTIONes. Desertification is the conversionNOT FOR of ordin SALEary for ORest DISTRIBUTIONor 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 linen, & Bartlettroses, orchids, Learning, or the pap erLLC that exami- rapidly eroded,© Jones making reco& Bartlettvery difficul Learning,t. Something LLC as sim- nationsNOT are wri FORtten on.SALE The oxygen OR DISTRIBUTION we breathe comes entirely ple as cheapNOT solar FORcookers SALE might preORvent DISTRIBUTION 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 &that Bartlett are not readi Learning,ly apparent LLC in our day-to-day lives. Listed© Jonessubdivisions, & Bartlett and sho Learning,pping malls LLC with enormous parking NOT FORhere SALE are a fewOR impo DISTRIBUTIONrtant topics you should be aware of. ThinkNOT lots;FOR these SALE eliminate OR almos DISTRIBUTIONt 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 to alter plants and anima© Jonesls, giv ing& Bartlettthem new Learning,traits and LLCOnce too little habitat is left, species© Jones usually & becomeBartlett extinct. Learning, LLC characteristics. Farmers have done this for thousands of Introduced exotics are organisms native to one part of the years with controlled breNOTeding FORof the bestSALE plants OR and DISTRIBUTIONanimals world but which have been broNOTught FOR to ano SALEther par t,OR wher DISTRIBUTIONe (artificial selection), but biotechnology permits much more they thrive. Examples of introduced exotic animals are fire rapid, extensive alterations. We must now consider whether ants in the southern United States and zebra mussels in the such manipulations are safe and worthwhile. Great Lakes region. Water hyacinth, purple loosestrife, and Global© Jones warming & Bartlett and climate Learning, change are LLCcaused by a kudzu (a vine)© Jones were intr &oduced Bartlett to the Learning, United States LLCand are buildup of carbon dioxide in our atmosphere caused by now proliferating and reproducing so vigorously that they burningNOT coal, FOR oil, gas,SALE and theOR tre DISTRIBUTIONes of forests everywhere are crowdingNOT out manyFOR plants SALE that ORnormally DISTRIBUTION grow here. (not just tropical rain forests). Carbon dioxide traps heat, It is not realistic to believe that we humans will stop all preventing Earth from radiating excess energy into space. activities that have negative impacts on our environment Global warming is causing polar ice caps to melt, and cli- and on the other species with which we share this planet, but mate change alters circulation of ocean currents and even we can search for ways to minimize the harm we cause by © Jones &the Bartlett amount and Learning, pattern of LLCrainfall. Preserving our forests© Jonesrecycling, & Bartlett conserving Learning, resources, and LLC avoiding products that NOT FORand SALE planting OR mor DISTRIBUTIONe trees might help stop and reverse globalNOT requireFOR SALEpollution-causing OR DISTRIBUTION manufacturing techniques.
(A) (B) FIGURE B1-1 Habitat loss is caused by many types of human activity. (A) This church parking lot covers acres of land previously used for grazing. Now it is used only 2 or 3 hours 1 day a week. Other than the few trees that were spared, it has no plants or animals, it prevents rain from soaking into the ground, and the asphalt leaches harmful chemicals into © Jones &nearby Bartlett creeks. No other Learning, business is nearby LLC that could use this parking lot on weekdays ©or at Jones night, which &would Bartlett at least provide Learning, additional benefit LLCto offset the ecological damage it NOT FORcauses. SALE (B) Even OR the construction DISTRIBUTION of beautiful parks is habitat destruction. NOT FOR SALE OR DISTRIBUTION Using Concepts to Understand Plants 9
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. 5. Plants must survive in their own environment. They must exist in future individuals long after this generation has be adapted to the conditions in the area where they live. passed away. © Jones & BartlettIf they are Learning, not adapted LLCto that area’s conditions, they© Jones8. Plants & Bartlett do not have Learning, purpose or LLCdecision-making capacity. NOT FOR SALEgrow andOR reproduce DISTRIBUTION poorly or die prematurely. OtherNOT FORIt is SALE easy to ORspeak DISTRIBUTION and write as if plants were capable of plants whose genes result in characters that make thinking and planning. We might say, “Plants produce those plants more suited to live in that area grow and roots in order to absorb water”; however, this suggests reproduce more successfully and produce more off- that the plants are capable of analyzing what they need spring. Also, plants do not exist in isolation: A signifi- and deciding what they are going to do. Assuming that cant aspect of a pla©nt’s Jones environment & Bartlett is the pres Learning,ence of LLCplants have human characters© Jones such as & tho Bartlettught and deci Learning,- LLC other organisms. SomNOTe neigh FORboring SALE orga nismsOR DISTRIBUTION may be sion-making capacity isNOT called FOR anthropomorphism SALE OR DISTRIBUTION, helpful to the plant; others may be harmful, and most and it should be avoided. Similarly, assuming that pro- perhaps have little effect on it. This concept can be cesses or structures have a purpose is called teleology, important when trying to understand a plant’s structure and it too is inaccurate. Consider an alternative way of and metabolism: One type of photosynthetic metabo- phrasing the sentence: “Plant roots absorb water,” leav- lism© Jones and leaf &str Bartlettucture may Learning, function wel lLLC if a particu- ing out© the Jones phrase “in& Bartlettorder to.” The Learning, reality of the LLC situa- larNOT plant FOR always SALE grows in OR the DISTRIBUTIONshade of taller neighbors, tion is NOTthat some FOR of the SALE information OR DISTRIBUTION in the plant’s genes whereas a different type of photosynthetic metabolism causes the plant to produce roots, which have a structure and leaf structure may be necessary for a plant that and a metabolism that result in water absorption. Plants grows nearby but in an unshaded area. have roots because they inherited root genes from their 6. Plants are highly integrated organisms. The structure ancestors, not in order to absorb water. Absorbing water © Jones & Bartlettand metabolism Learning, of one LLCpart have some impact on the© Jonesis & a beneficialBartlett resu Learning,lt that aids in LLC the survival of the plant, NOT FOR SALErest of OR the plant.DISTRIBUTION When studying the biology of leaves,NOT FORbut SALE it is not theOR resu DISTRIBUTIONlt of a decision (anthropomorphism) consider how the structure and metabolism of stems, or purpose (teleology). roots, epidermis, and other parts might affect the func- tion of those leaves. Large leaves absorb more sunlight and energy than small leaves; however, if a plant has large leaves, it may© nee Jonesd to hav &e aBartlett large root Learning,system to LLC❚❚ Origin and Evolution© Jones & Bartlett Learning, LLC absorb water and NOTmineral FORs for theSALE leaves, OR and DISTRIBUTION it may of Plants NOT FOR SALE OR DISTRIBUTION need wide stems to conduct enough water and minerals from the roots to the leaves. Keep in mind that structure Life on Earth began about 3.5 billion years ago. At first, liv- and metabolism must be integrated: The structure of a ing organisms were simple, like present-day bacteria, in both cell, tissue, or organ must be compatible with the met- their metabolism and structure; however, over thousands abolic© Jones function & Bartlettof that sam Learning,e cell, tissue, orLLC organ. For of millions ©of Jonesyears cell &s gradu Bartlettally incre Learning,ased in comp LLClexity example,NOT FOR if a leaf SALE is fibr ousOR and DISTRIBUTION tough, insects may find through evolutionNOT FOR by nat SALEural sele ction.OR DISTRIBUTION The process is easy it unpalatable and may avoid eating it; however, if the to understand: As organisms reproduce, their offspring dif- leaf is too fibrous, the fibers may block the absorption of fer slightly from each other in their features—they are not sunlight. Such a structure would be incompatible with identical. Offspring with features that make them poorly photosynthesis. adapted to the habitat probably do not grow well and repro- © Jones &7. BartlettAn individual Learning, plant is the LLC temporary result of the inter-© Jonesduce &poorly Bartlett if the yLearning, live long enoug LLCh to become mature NOT FOR SALEaction OR of genes DISTRIBUTION and environment. Be careful to considerNOT (FigureFOR SALE1-11 and OR FIGURE DISTRIBUTION 1-12). Other offspring with features differences between an individual plant and that plant’s that cause them to be well-adapted grow well and reproduce species (the group made up of all similar plants). Con- abundantly, passing on the beneficial features to their own sider something like a sunflower: An individual plant offspring. This is called natural selection. New features exists because its parents underwent reproduction and come about periodically by mutations, and natural selection one of their seeds ©lan Jonesded in a& suit Bartlettable envir Learning,onment, LLCdetermines which new features© Jonesare elimina & Bartlettted and which Learning, LLC where the informationNOT in FOR the see SALEd’s genes OR interac DISTRIBUTIONted are passed on to future generaNOTtions. FOR Evolution SALE by ORnatural DISTRIBUTION with the environment by way of the seed’s structure selection is a model consistent with observations of natural and metabolism. There are two concepts of “sunflower” organisms, experiments, and theoretical considerations. here: (1) the actual plant that we can observe, measure, As early organisms became more complex, major cultivate, and enjoy and that interacts with its environ- advances occurred. One was the evolution of the type of pho- ment,© Jones absorbs & reso Bartletturces, resp Learning,onds to cha LLCnges, attracts tosynthesis© tha Jonest produces & Bartlettoxygen and Learning, carbohydrates. LLC This pollinators,NOT FOR and SALE resists ORpathogens DISTRIBUTION and (2) the genetic photosynthesisNOT is presFORent SALEin all gre ORen pla DISTRIBUTIONnts, but it first arose information that guides all of this and that has existed about 2.8 billion years ago in a bacterium-like organism for thousands of years, evolving gradually as it has been called a cyanobacterium. Later, cell structure became more passed down through all the ancestors of this particular efficient as subcellular components evolved. These compo- individual sunflower. This information does not exist nents, called organelles, each provide a unique structure and © Jones & Bartlettonly in this Learning, one individual LLC but rather in all of the cur-© Joneschemistry & Bartlett specialized Learning, to a specific funcLLCtion. Division of labor NOT FOR SALErently ORliving DISTRIBUTION sunflower individuals. It will continue toNOT andFOR specialization SALE OR had DISTRIBUTION come about. 10 Chapter 1: Introduction to Plants and Botany
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. A particularly significant evolutionary step occurred when DNA, the molecule that stores hereditary informa- © Jones & Bartlett Learning, LLC © Jonestion, became& Bartlett located Learning, in its own orga LLCnelle—the cell nucleus. NOT FOR SALE OR DISTRIBUTION NOT BecauseFOR SALE this step OR was DISTRIBUTION so important and occurred with so many other fundamental changes in cell metabolism, we classify all cells as prokaryotes if they do not have nuclei (bacteria, cyanobacteria, and archaeans) or as eukaryotes if they do have nuclei (all plants, animals, fungi, and algae) © Jones & Bartlett Learning, LLC(Table 1-1). © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONBy the time nuclei becameNOT esta FORblished, SALE evolution OR had DISTRIBUTION produced thousands of species of prokaryotes. The newly evolved eukaryotes also diversified. Some acquired an energy- transforming organelle, the mitochondrion, and some acquired chloroplasts, which carry out photosynthesis and © Jones & Bartlett Learning, LLC convert the© energ Jonesy in sunlig& Bartlettht to the Learning, chemical energ LLCy of NOT FOR SALE OR DISTRIBUTION carbohydrates.NOT Those FOR wit SALEh chloroplasts OR DISTRIBUTION evolved into algae and plants; those without evolved into protozoans, fungi, and animals (FIGURE 1-13). All organisms are classified into three large groups Herman, Copyright 1985, Universal Press Syndicate. Reprinted with permission. All rights reserved. called domains: domain Bacteria, domain Archaea, and © Jones & BartlettFIGURE 1-12 Learning, Mutations that produceLLC disadvantageous features © Jonesdomain & BartlettEukarya; witLearning,hin Eukarya LLC are kingdom Plantae, NOT FOR SALEusually OR contribute DISTRIBUTION to the death, sooner or later, of an organism. If NOT kingdomFOR SALE Animalia, OR kingDISTRIBUTIONdom Myceteae (fungi), and pro- the individual cannot undergo reproduction (because it is dead), tists (eukaryotes that do not fit easily into the other three it cannot pass the mutation on to offspring and the deleterious eukaryotic kingdoms). Some protists are closely related to mutation is eliminated. Plantae because some green algae became adapted to living © Jones & Bartlett Learning, LLCon land and gradually evolved© Jonesinto true &pla Bartlettnts. As a conLearning,- LLC sequence, early plants resembled those green algae, but as NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
Animals Fungi Protozoans Algae Plants FIGURE 1-13 The earliest cells were simple, but over hundreds of millions of years they became more complex metabolically. Later, © Jones & Bartlett Learning, LLC © Jones & Bartlettsome evolved intoLearning, simple eukaryotic LLC cells Eukaryote with a true nucleus, which later developed NOT FOR SALE OR DISTRIBUTION withNOT FOR SALE OR DISTRIBUTION mitochondria mitochondria. Some of these evolved into and chloroplasts protozoans, animals, and fungi. Others developed chloroplasts and evolved into plants. Protozoans and algae are protists. Eukaryote © Jones & Bartlett Learning,with LLC © Jones & Bartlett Learning, LLC mitochondria NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
Early eukar© Jonesyote & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC withNOT nucleus FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC Later© Jones & Bartlett Learning, LLC prokaryotes NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Early prokaryote NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Origin and Evolution of Plants 11
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. more mutations occurred and natural selection eliminated In the same way that different groups evolve at differ- less adaptive ones, plants lost algal characteristics and gained ent rates, various features also evolve at different rates. For © Jones more& Bartlett features suitLearning,ed to surviving LLC on land. Thousands of spe-© Jonesinstance, & Bartlett the asters Learning,are a mixture LLC of the recently derived NOT FORcies SALE arose, butOR most DISTRIBUTION became extinct, as those that were moreNOT antiherbivoreFOR SALE comp ORounds, DISTRIBUTION less recently derived flowers, and fit grew more rapidly, survived longer, and produced more still less recently derived wood. In addition, their bodies offspring. Species that did not become extinct evolved into are covered with a waxy waterproof layer, the cuticle, that more species and so on. The living plants that surround us has not changed much since land plants first evolved about are the current result of the continuous process of evolution. 420 million years ago, and their leaves contain chloroplasts Not all organisms ©evo Joneslve at the & sam Bartlette rate; som Learning,e early LLCand nuclei that are much like© thos Jonese of gre &en Bartlett algae and Learning, are LLC species were actually so NOTwell adap FORted tha SALEt they comp OR etedDISTRIBUTION suc- extremely relictual. NOT FOR SALE OR DISTRIBUTION cessfully against newer species. Algae are so well suited to life in oceans, lakes, and streams that they still thrive even though most features present in modern, living algae must ❚❚ Diversity of Plant be more or less identical to those present in the ancestral algae ©that Jones lived mor & eBartlett than 1 bil lionLearning, years ago. LLCFeatures that Adaptations© Jones & Bartlett Learning, LLC seem NOTrelatively FOR unch SALEanged areOR relictual DISTRIBUTION features (techni- NOT FOR SALE OR DISTRIBUTION cally known as plesiomorphic features; formerly called More than 297,000 species of plants exist today. An unknown primitive features). Like the algae, ferns are well-adapted to number of species, perhaps also several hundred thousand, certain habitats and have not changed much in 250 million existed at one time but have become extinct. Virtually all of this years; they too have many relictual features. Modern conifers diversity came about through evolution by natural selection— © Jones &are Bartlett similar to Learning,early ones tha tLLC arose about 320 million years© Jonessurvival & ofBartlett the fittest; Learning, however, the LLCexistence of 297,000 types NOT FORago. SALE The most OR recen DISTRIBUTIONtly evolved group consists of the flower-NOT ofFOR living SALE plants mea ORns DISTRIBUTIONthat there must be at least 297,000 ways ing plants, which originated about 100 to 120 million years of being fit on today’s Earth. For any particular aspect of the ago with the evolution of several features: flowers; broad, environment, many types of adaptation are possible. There is flat, simple leaves; and wood that conducts water with little not one single, exclusive, perfect adaptation. Consider plants growing in a climate with freezing winters. Frozen soil is friction. The members ©of theJones aster &famil Bartletty (sunflow Learning,ers, dai- LLC © Jones & Bartlett Learning, LLC sies, and dandelions) (FIGURE 1-14) have many features that physiologically dry because roots cannot extract water from evolved recently from featuresNOT FORpresent SALE in ancestral OR flowering DISTRIBUTION it. If the winter air is dry andNOT wind y,FOR shoots SALE lose water OR, and DISTRIBUTION plants. These are derived features (technically known as plants are in danger of dying from dehydration. How can apomorphic features; formerly called advanced features) plants adapt to this? Mutations that cause leaves to fall off (i.e., they have been derived evolutionarily from ancestral in autumn and mutations that cause bark to develop on all exposed parts of the stem reduce the surface area through features).© Jones One recen & tBartlett (highly deriv Learning,ed) feature inLLC the asters is © Jones & Bartlett Learning, LLC a group of chemical compounds that discourage herbivores which water is lost; such mutations are advantageous in this from NOTeating theFOR plants. SALE The term ORs “prDISTRIBUTIONimitive” and “advanced” environment,NOT and FOR many SALEspecies hav ORe thes DISTRIBUTIONe adaptations. In are avoided in that they imply inferior and superior. other species, the entire shoot system above ground dies, but subterranean bulbs, corms, or tubers persist and pro- duce a new shoot the next spring. Another adaptation is for the plant itself to die but its seeds to live through the harsh © Jones & Bartlett Learning, LLC © Jonesconditions. & Bartlett Finally, Learning,evergreen spe ciesLLC retain both stem and NOT FOR SALE OR DISTRIBUTION NOT leaves,FOR SALEbut the leavORes DISTRIBUTION have extra thick cuticles and other modifications that minimize water loss. This diversity is extremely important, and you must be careful to think in terms of alternative adaptations, alterna- tive methods of coping with the environment. The physi- © Jones & Bartlett Learning, LLCcal and biological world is made© Jones up of gradients: & Bartlett It is Learning,not LLC NOT FOR SALE OR DISTRIBUTIONsimply either hot or cold butNOT rath erFOR rang SALEes continuously OR DISTRIBUTION from hot in some areas at some times to warm, cool, and cold in the same or other areas at other times. Roots face a range of water availability from flooded, waterlogged soil to moist, somewhat dry, and even arid soil (FIGURE 1-15). © Jones & Bartlett Learning, LLC Studying and© Jones unders tanding& Bartlett plants Learning, and their survLLCival NOT FOR SALE OR DISTRIBUTION require thatNOT we place FOR the SALE plant in OR the DISTRIBUTIONcontext of its habi- tat: What are the significant environmental factors? What FIGURE 1-14 This is Gazania splendens in the aster family. It has many derived predators and pathogens must it protect itself from? What features, especially the bitter, toxic chemicals (iridoid compounds) in its leaves; lettuce physical stresses must it survive? What are the advan- is in the same family, but plant geneticists have eliminated the genes that produce the tageous, helpful aspects of its habitat? When you think antiherbivore features. As a result, lettuce is sweet both to us and to insects, rabbits, in terms of gradients and ranges of habitat factors, you © Jones &and Bartlettdeer. Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT appreciateFOR SALE the rang ORe of DISTRIBUTION responses and adaptations that exists. 12 Chapter 1: Introduction to Plants and Botany
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Our observations and interpretations constitute a body of knowledge that is both incomplete and inaccurate. Because © Jones & Bartlett Learning, LLC © Joneswe do & not Bartlett know ever Learning,ything about allLLC organisms, our knowl- NOT FOR SALE OR DISTRIBUTION NOT edgeFOR is SALEan incom ORplete DISTRIBUTION reflection of reality, and at least some of our hypotheses are wrong. In college courses, even intro- ductory botany, you study areas where we are still gather- ing information and our knowledge is incomplete. Often, not enough data are present to form coherent hypotheses in © Jones & Bartlett Learning, LLCwhich we can have great confidence© Jones. You & mus Bartlettt think car Learning,e- LLC NOT FOR SALE OR DISTRIBUTIONfully about the things you readNOT and hea FORr and SALEanalyze whetORher DISTRIBUTION they seem reasonable and logical and have been verified. As you read, you will deal with two types of information: observations and interpretations. Most observations are reasonably accurate and trustworthy; we usually have to © Jones & Bartlett Learning, LLC consider only© Joneswhether &the Bartlett botanist wasLearning, careful, obser LLCved NOT FOR SALE OR DISTRIBUTION correctly andNOT without FOR erro SALEr, and repoORrted DISTRIBUTION truthfully. Inter- FIGURE 1-15 A mountain provides many types of environments. Higher altitudes are pretations are more difficult; they are entirely human con- always covered with snow and ice; no plants can survive there. In the lower, warmer structs based on observations, intuition, previous experience, altitudes, the steep slopes allow rain to run off rapidly, so the soil is dry. Conifers are calculations, and expectations. How can we judge whether well-adapted to these conditions. In the flat valley bottoms, water accumulates as an interpretation has any relation to reality? A correct scien- © Jones &marshes; Bartlett the roots of Learning, sedges and rushes can LLC tolerate the constant moisture, but the © Jonestific interpretation & Bartlett mus Learning,t make an accuratLLC e prediction about roots of conifers would drown. Each type of plant is adapted to specific conditions, the outcome of a future observation or experiment. NOT FOReven SALE though they OR grow DISTRIBUTION almost side by side. NOT FOR SALE OR DISTRIBUTION Your study of the material in this book, as well as your studies of plants themselves, will be easier if you keep in mind two questions that can be asked about any biological ❚❚ Plants Versus the Study phenomenon: © Jones & Bartlett Learning, LLC1. Are there alternatives to this© phenomenon? Jones & BartlettDo other struc Learning,- LLC of Plants NOT FOR SALE OR DISTRIBUTIONtures exist that could perfNOTorm tha FORt same SALEfunction? OR Cou DISTRIBUTIONld a different metabolic pathway also occur? If no alternative Mathematicians, physicists, and chemists study the world and is possible, why not? If alternatives are possible, do they derive interpretations that are considered universally valid. The exist? Did they evolve and then become extinct? relationships of numbers to each other are the same every- For example, consider photosynthesis: Do plants have where© in Jones the Univ erse;& Bartlett if intelligent Learning, beings exist els LLCewhere, their alternative© Jones sources &of Bartlettenergy oth Learning,er than sunlig LLCht? We mathematiciansNOT FOR wil lSALE discover OR exactl DISTRIBUTIONy the same mathematical concludedNOT earlier FOR in theSALE chapter OR tha DISTRIBUTIONt parasitic plants do relationships. The same is true for physics and chemistry. not need sunlight; they can grow in dark areas. Also, Some aspects of biological knowledge also are univer- most seeds germinate underground, in complete dark- sally valid: All metabolic processes, either on Earth or else- ness. Therefore, it seems at first glance that there are where in the Universe, can be predicted by mathematics, alternatives to photosynthesis; however, parasitic plants © Jones &physics, Bartlett and chemi Learning,stry. Organi LLCsms everywhere must take in© Jonesdepend & Bartlett on host Learning, plants that do LLC carry out photosynthe- NOT FORenergy SALE and OR mat terDISTRIBUTION and convert it metabolically into the sub-NOT FORsis, SALE and germinating OR DISTRIBUTION seeds rely on stored nutrients they stance of their own bodies. This cannot be done with perfect obtained from their parent plant. All plants must, there- efficiency, and thus, all organisms produce waste heat and fore, receive adequate sunlight, at least indirectly. On a waste matter. Furthermore, all organisms must be capable of theoretical basis, it seems possible that an insect-trapping reproduction and must have a system of heredity. plant like a Venus flytrap might become so efficient However, biologists© stud Jonesy orga nisms& Bartlett that exist Learning, only on LLCthat it could live solely by© catJonesching anima& Bartlettls, but non Learning,e LLC Earth, and we are reasonablyNOT FORcertain SALE that if ORlife exists DISTRIBUTION on is known to be that efficient:NOT They FOR cat SALEch only enougOR DISTRIBUTIONh some other planet, it is not exactly like life here (BOX 1-2). insects to provide a little extra nitrogen, not enough to Much of what we study does not have universal truth; there- provide the plant with all of the energy it needs. fore, knowing about certain plants in certain habitats does 2. What are the consequences? What are the consequences not let us predict precisely the nature of other plants in other of a particular feature as opposed to an alternative fea- habitats.© Jones Much of &our Bartlett knowledge Learning, is applicable LLConly to a par- ture or© the Jones absence & of Bartlett the feature? Learning, Every feature, LLC struc- ticularNOT set of FOR plants orSALE a certa ORin meta DISTRIBUTIONbolism. In the biological ture, orNOT metabolism FOR SALE has cons ORequences DISTRIBUTION for the plant, sciences, the fundamental principles have universal validity, making it either better or less well adapted. Some may but many details are peculiar to the organisms being studied. have dramatic, highly significant consequences; others As biologists study organisms, we attempt to create a may be close to neutral. When you consider the conse- model of an unknown world. Plants are part of reality, and quences of a particular feature, you must consider the © Jones &the Bartlett study of pla Learning,nts attempts toLLC create a model of that reality© Jonesbiology & Bartlett of the pla Learning,nt in its natural LLC habitat as it faces com- NOT FORand SALE build aOR voc DISTRIBUTIONabulary to exchange ideas about the reality.NOT FORpetition, SALE predators, OR DISTRIBUTION pathogens, and stresses. Plants Versus the Study of Plants 13
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & BartlettPlants Learning, and LLC People © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION BOX 1-2 The Characteristics of Life
Botany is a subdivision© of Jonesbiology, the& Bartlettstudy of life. Learning, Despite LLC2. Nonrandom organization.© JonesAll organisms & Bartlett are highl Learning,y LLC the importance to biology of defining life, no satisfactory def- structured, and decay is the process of its molecules inition exists. As we studNOTy meta FORbolism, SALE structure, OR and DISTRIBUTION ecology returning to a random NOTarrangement; FOR SALEhowever, OR man DISTRIBUTIONy more closely, we understand many life processes in chemical/ nonliving systems also have this feature: Crystals have physical terms. It is difficult to distinguish between biology an orderly arrangement as do many cloud patterns, and chemistry or between living and nonliving, but the lack weather patterns, and ripple patterns in flowing streams. of a definition© Jones for & life Bartlett does not Learning,bother biolog ists;LLC very few 3. Growth.© AllJones organisms & Bartlett increase inLearning, size from the LLC time short definitions are accurate, and life is such a complex and they are formed: Fertilized eggs grow into seeds or importantNOT subject FOR tha SALEt a ful l ORunders DISTRIBUTIONtanding gained through embryos,NOT and FOR each SALEin turn ORgrows DISTRIBUTION into an adult. At extensive experience is more useful than a definition. some point, growth may cease—we stop getting taller Although we cannot define life, it is critically important for at about 25 years of age. This too is not sufficient to dis- us to recognize it and to know when it is absent. Many hospitals tinguish living from nonliving: Mountains and crystals © Jones &use Bartlett artificial vent Learning,ilators, bloo dLLC pumps, and drugs to maintain© Jonesalso & Bartlettgrow. Learning, LLC the bodies of victims of accidents or illness. The person’s cells are 4. A system of heredity and reproduction. An organism NOT FORalive, SALE but is ORthe pers DISTRIBUTIONon alive? On a less dramatic scale, how doesNOT FORmust SALE produce OR offsp DISTRIBUTIONring very similar to itself such that one recognize whether seeds are alive or dead? A farmer about when the individual dies life persists within its progeny. to spend $100,000 on seed corn wants to be certain that the seed Fires reproduce but are not alive. is alive. How do we recognize that coral is alive? It looks like rock 5. A capacity to respond to the environment such that metab- but grows slowly—but stalactites© Jones are rock & Bartlettand they also Learning, grow. LLColism is not adversely affected.© Jones When conditions& Bartlett beco Learning,me LLC The ability to recognize life or its absence is important in dry, an organism can respond by becoming dormant, space exploration also. TheNOT surface FOR of Mar SALEs is dry, ORbut water DISTRIBUTION may conserving water, or obtNOTaining FORwater morSALEe effec ORtively. DISTRIBUTION exist within the soil; many bacteria on Earth live below ground, Mountains also respond to the environment by growing obtaining energy from chemicals in rock. Europa, a moon of as geological forces push them upward and by becoming Jupiter, has an ocean below a layer of permanent ice; on Earth, smaller as erosion wears them away. worms,© clams,Jones and & bact Bartletteria live in Learning, complete, icy LLCdarkness near In addition© Jones to thes &e abso Bartlettlute req Learning,uirements of life,LLC two vents on the ocean floor, obtaining enough energy from vol- NOT FOR SALE OR DISTRIBUTION features areNOT almos tFOR certainly SALE associated OR witDISTRIBUTIONh all forms of life: canic gases to thrive, not just survive. When we explore Mars, (1) Organisms develop, such that young individuals and old Europa, and other parts of the solar system, how will we search ones have distinctive features, and (2) organisms evolve, for life? How will we know whether we have found it? changing with time as the environment changes. All living beings have all of the following characteristics; Although these various features are always present in if even one is missing, the material is not alive: © Jones & Bartlett Learning, LLC © Jonesliving & creatures, Bartlett no Learning, one characteristic LLC is sufficient to be NOT FOR 1. SALEMetabolism OR DISTRIBUTION involving the exchange of energy and matterNOT certainFOR SALEthat som ORething DISTRIBUTION is living versus inanimate. We have with the environment. Organisms absorb energy and no difficulty being certain that rivers, fire, and crystals are matter, convert some of it into their own bodies, and not living, but when we search for life on other planets excrete the rest. Many nonliving systems also do this: or even in some exotic habitats here on Earth, deciding Rivers absorb water from creeks, mix it with mud and whether we have actually discovered life might be quite boulders, and then ©“excrete” Jones it into & Bartlettoceans. Learning, LLCproblematical. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
FIGURE B1-2A Lichens grow extremely slowly and FIGURE B1-2B These seeds of corn (Zea mays) are alive and © Jones & Bartlettremain Learning, dormant for months; LLC almost no sign of life © Jones &healthy, Bartlett but inactive Learning, metabolically. They LLC will germinate and NOT FOR SALE ORcan be DISTRIBUTION detected during their dormant period. NOT FOR SALEbecome obviously OR alive, DISTRIBUTION but only if given the proper conditions. 14 Chapter 1: Introduction to Plants and Botany
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & BartlettPlants Learning, and LLC People © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION BOX 1-3 Algae and Global Warming
Photosynthesis removes© carbJoneson dioxide & Bartlett from theLearning, atmo- LLCAlgae, the close relatives ©of plaJonesnts, ar e& a grBartlettoup of or ganLearning,- LLC sphere and helps keep Earth cool enough for us to live. Vari- isms that are important allies in our attempts to combat global ous organisms other thaNOTn plants FOR are pho SALEtosynthetic OR andDISTRIBUTION help warming. There are many typesNOT of algae FOR (most SALE are nam ORed DISTRIBUTIONby reduce the amount of carbon dioxide in our air. Two types the color of their pigments, such as red algae, green algae, of bacteria, called “purple bacteria” and “green bacteria,” brown algae, and so on), and all carry out photosynthesis have an unusual type of photosynthesis that differs from that that is almost identical to that of plants. Furthermore, algae of plants© Jones but allo ws& Bartlettthose bact eriaLearning, to absorb LLCcarbon diox- are abundant© inJones oceans, & lak Bartlettes, and riv ersLearning, as well as inLLC moist ide from the environment and keep it out of the air. Purple soils, rocks, and even tree bark. Just like plants, algae absorb bacteriaNOT and FOR green SALEbacteria OR are botDISTRIBUTIONh rather rare, so they carbon dioxideNOT as FORthey pho SALEtosynthesize OR DISTRIBUTION and lock it into the do not remove very much carbon dioxide. Other bacteria, molecules of their bodies. Like bacteria, many algae are so called “cyanobacteria,” are extremely common and carry out delicate they decompose quickly after they die, so they do a type of photosynthesis that is very similar to that of plants. not keep carbon dioxide out of the air for long. © Jones &Cyanobacteria Bartlett Learning, grow in man yLLC types of soil as well, in ponds© JonesHowever, & Bartlett microsco Learning,pic algae, LLC called coccolithopho- and streams, and especially abundantly in sewage. The total rids (or just coccoliths), make a shell of calcium carbonate NOT FORamount SALE of OR cyanobacteria DISTRIBUTION in the world is great enough thaNOTt (FORFIGURE SALE B1-3). This OR shell DISTRIBUTION is so dense that as soon as the coc- they remove significant amounts of carbon dioxide from the coliths die, their bodies sink to the bottom of the oceans. air. Unfortunately, all bacteria are tiny and their bodies are The cold temperatures there slow decay to such a degree that rather delicate, so they break down quickly after they die and the shells do not break down for thousands, even millions the carbon atoms in their© bodies Jones are &conv Bartletterted back Learning, into car- LLCof years. Consequently, as thes©e microscoJones pic& Bartlettalgae grow Learning,and LLC bon dioxide. But if the bacteria are eaten by an animal, then then die, carbon dioxide is removed from the atmosphere the carbon-containing NOTmolecules FOR in SALEtheir bodies OR DISTRIBUTIONbecome for very long times. One ofNOT the possi FORbilities SALE for combOR atDISTRIBUTION- part of the bodies of the animals, and if those animals are ing global warming is to make these algae grow faster and then eaten by others, the carbon continues to be locked up in more abundantly by fertilizing the oceans in areas where a body rather than going back into the air. However, this only coccoliths already live. The hypothesis is that by adding just keeps© carbon Jones dioxide & Bartlett out of the Learning, atmosphere forLLC just a few enough of the© Jones right kind &s Bartlettof nutrients, Learning, coccoliths wil LLCl grow years at most, because no animal lives for more than a few rapidly enough to start removing large amounts of carbon decades.NOT Even FOR long-li SALEved anima ORls DISTRIBUTIONshed hair, skin, and other dioxide thatNOT will offset FOR much SALE of the OR dam DISTRIBUTIONage we do by burn- parts and defecate: All these decompose, and their carbon is ing petroleum and coal. So far, experimental trials have been converted to carbon dioxide. encouraging.
FIGURE B1-3 Limestone is calcium carbonate, composed of the shells of sea animals such as clams, mollusks, and certain algae. As these creatures formed their shells, they removed © Jones &carbon Bartlett dioxide from theLearning, atmosphere, causing LLC the climate to become cooler. All the rock© in thisJones area along & the BartlettPecos River is part Learning, of a gigantic region LLC of limestone that extends for NOT FORhundreds SALE of square OR miles. DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Plants Versus the Study of Plants 15
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Consider photosynthesis again. A consequence of depending on photosynthesis is that plants with many © Jones & Bartlettlarge leaves Learning, can harvest morLLCe light than plants with few©, Jones & Bartlett Learning, LLC NOT FOR SALEsmall ORleaves; DISTRIBUTION however, a consequence of having largeNOT FOR SALE OR DISTRIBUTION leaves is that they lose more water, they are more easily seen by hungry leaf-eating animals, they are good land- ing sites for disease-causing fungal spores, and so on. A further consequence of obtaining energy from sunlight is that the light does© not Jones need to & be Bartlett hunted the Learning, way that LLC © Jones & Bartlett Learning, LLC animals must huntNOT for their FOR food. SALE Because OR the sunDISTRIBUTION rises NOT FOR SALE OR DISTRIBUTION every morning, plants can just sit in one spot and spread their leaves (FIGURE 1-16). They do not need eyes, brains, © ivandzyuba/iStockPhoto muscles, or digestive systems to locate, catch, and con- sume their source of energy. Plants can be very simple FIGURE 1-16 This tree obtains its energy from sunlight, which and© Jonessurvive, whereas& Bartlett most animals Learning, must be LLC complex. is always ©located Jones in the sky; &the plantBartlett does not have Learning, to hunt for it. LLC Sophisticated sense organs and the power of movement are completely NOT FOR SALE OR DISTRIBUTION unnecessary;NOT having FOR them would SALE not make OR the plant DISTRIBUTION more adapted. Finally, no matter where you are, plants are readily avail- able for direct observation. You can figure out a great deal by observing a plant and thinking about it (as opposed to just boring to memorize names and terms, but if you think about observing it). You will be surprised at how much you already the material, analyze it, understand it, and see where it is not © Jones &know Bartlett about pla Learning,nts. As you read LLC, think about how the princi-© Jonesvalid for& Bartlettall plants or Learning, all situations, LLCyou will find both botany NOT FORples SALE discussed OR app DISTRIBUTIONly to plants you are familiar with. It can beNOT andFOR plants SALE to be ORenjoyable. DISTRIBUTION
© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC At theNOT FOR Next SALE LevelOR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
1. Independent, advanced study. The purpose of these At the and discarded. I recommend three books. Two, The Next© Jones Level boxes & Bartlett is to sugg Learning,est to you infor LLCmation that Epic History© Jones of Biology & Bartlett by Anthony Learning, Serafini (1993, LLC Per- wouldNOT be FOR relevant SALE to a mor ORe advanDISTRIBUTIONced understanding of seus Publishing)NOT FOR and SALE History OR of Botanical DISTRIBUTION Science: An the topics of the current chapter. Because Chapter 1 is an Account of the Development of Botany from Ancient introductory chapter, most of its topics will be developed Times to the Present Day by A. Morton (1982, Academic later in this book, and if you would like to read ahead Press), are shorter, more direct, and easy to follow. The now, just check the table of contents and find topics that third book, The Growth of Biological Thought: Diversity, © Jones & Bartlettappeal to you.Learning, Also, leaf LLCthrough the book and read var-© JonesEvolution, & Bartlett and InheritanceLearning, by LLC Ernst Meyer (1985, Bel- ious boxes or figure legends: these are short enough that knap Press), is more detailed and parts will be difficult NOT FOR SALEyou can OR easily DISTRIBUTION read through those you find interesting andNOT FORfor SALEa freshman OR or DISTRIBUTION sophomore, but it is a book that any skip the others. biologist should read; it is a book you will want to have 2. The development of our current concepts. We are famil- for the rest of your life. iar with concepts of cells, plants, life, gravity, energy, 3. Science and ethics. The scientific method cannot deal with motion, and many© oth Joneser phen omena.& Bartlett But our Learning, present LLCthings that are not tangible© or Jonesphysical, and& Bartlett certainly pla Learning,nts LLC understanding is the result of thousands of years of never face ethical or moral dilemmas, but we humans do. trying to understandNOT the worFORld. ISALE recommend OR DISTRIBUTIONreading Ethics and morality are notNOT my spe FORcialty andSALE I will notOR rec DISTRIBUTION- a bit of the history of science, especially the history ommend any particular book or article, but I do strongly of biology. You will be amazed to learn that concepts suggest that you think about ethics and search out infor- we assume have always been known had to be discov- mation on your own. An Internet search is a good place ered;© Jones other concep & Bartlettts that most Learning, of us hav eLLC never heard to start,© and Jones book rev& iewsBartlett on Amazo Learning,n.com are excelLLClent of had been widely accepted but had to be disproven guides as to which books might be of value to you. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 16 Chapter 1: Introduction to Plants and Botany
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. SUMMARY © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR 1. SALEIt is difficult OR DISTRIBUTION to define a plant. It is more important toNOT FOR4. Living SALE organisms OR DISTRIBUTIONhave evolved by natural selection. As develop a familiarity with plants and understand how organisms reproduce, mutations cause some offspring to be they differ from animals, fungi, protists, and prokary- less fit, some to be more fit. Those whose features are best otes. The differences are presented in later chapters. suited for the environment grow and reproduce best and 2. The scientific method requires that all information be leave more offspring than do those that are poorly adapted. gathered through docum© Jonesented, & repe Bartlettatable obser Learning,vations LLC5. For any particular environment,© Jones several & typesBartlett of adap Learning,ta- LLC and experiments. ItNOT rejects FOR any concep SALEt tha ORt can nevDISTRIBUTIONer be tion can be successful. NOT FOR SALE OR DISTRIBUTION examined, and it requires that all hypotheses be tested 6. Our knowledge of the world is incomplete and inac- and be consistent with all relevant observations. It is curate; as scientific studies continue, incompleteness based on skepticism. diminishes and inaccuracies are corrected. 3. Science and religion address completely different kinds 7. Two simple questions are powerful analytical tools: of© problems.Jones &Science Bartlett cann Learning,ot solve mora LLCl problems; (1) What© Jonesare the &alt ernatives,Bartlett and Learning, (2) what LLCare the religionNOT FORcannot SALEexplain physicalOR DISTRIBUTION processes. consequences?NOT FOR SALE OR DISTRIBUTION
© Jones &anthropomorphism Bartlett Learning, LLC hypothesis © Jones & Bartlettrelictual Learning, features LLC NOT FORapomorphic SALE OR features DISTRIBUTION interpretations NOT FOR SALE ORscientific DISTRIBUTION method botany natural selection teleology derived features observations theory domains plesiomorphic features
© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC REVIEW QUESTIONSNOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
1. Your present concept of plants is probably quite accurate. 7. The scientific method deals only with ______Most have roots, stems, leaves, and flowers. Can you ______phenomena and objects. name two plants that have cones rather than flowers? 8. Physical forces that control the world are ______Can© Jones you name & a Bartlettplant that appears Learning, to not haveLLC leaves? through© timeJones and are& Bartlettthe ______Learning, everywhere. LLC 2. NameNOT two FOR types SALE of fung ORi. Why DISTRIBUTION were fungi originally 9. The fundamentalNOT FOR basi SALEs of ORthe scientDISTRIBUTIONific method is included in the plant kingdom? Biologists no longer ______. Describe this concept. consider fungi to be plants because they differ in many 10. What is a hypothesis? A theory? Why is it important basic ______and ______aspects. that each be able to predict the outcome of a future 3. How would you distinguish between plants and animals? experiment? How do these differ from a speculation? © Jones & BartlettWhat characters Learning, are impo LLCrtant? Be careful to consider© Jones11. If& aBartlett hypothesis Learning, makes predictions LLC that are not accu- NOT FOR SALEunusual OR plants DISTRIBUTION and animals. Can all animals move? DoNOT FORrate SALE and do OR not DISTRIBUTION help explain future observations, do they all eat? those inaccurate predictions prove the hypothesis is 4. What are three methods for analyzing nature? Name not a good model of reality? On the other hand, if the some advantages and disadvantages of each. hypothesis does make accurate predictions, does that 5. Is it always easy to recognize that something is a liv- accuracy prove the hypothesis is correct? ing being rather tha©n Jonesan inanim &ate Bartlett object? Euro Learning,pa is a LLC12. Do any concepts exist for© whichJones the & scient Bartlettific meth Learning,od LLC moon of Jupiter (seeNOT Box 1-FOR2), and SALE it is so ORfar fro DISTRIBUTIONm the is inappropriate? Some peoNOTple sufferFOR terr SALEibly fro ORm cer DISTRIBUTION- sun that there is not enough light for photosynthesis. tain incurable diseases. Can scientific methods be used The bottom of its ocean must be completely dark and to develop drugs that could end a person’s life? Can sci- icy cold. Are there locations like this on Earth that sup- entific methods be used to decide whether it is right or port life and that therefore let us hypothesize that life wrong to use such drugs? Do you think the concept of might© Jones also exist & Bartletton Europa? Learning, LLC right ©and Jones wrong actu& Bartlettally exists? Learning,Can you prove LLC it with 6. InNOT the scientific FOR SALE method, OR all accepte DISTRIBUTIONd information can be scientificNOT methods? FOR SALEAre righ tOR and DISTRIBUTIONwrong concepts that derived only from documented and controlled ______can be measured, weighed, dissected? Do they have a ______or ______. If chemical composition? someone claimed to have a new treatment of a disease 13. List the eight concepts that can be used to understand or a new type of eye surgery, would you want some sort plants. © Jones & Bartlettof documentation Learning, and proLLCof before you let them give© Jones14. The& Bartlett first concept Learning, used to unders LLCtand plants is that plant NOT FOR SALEyou drugs OR orDISTRIBUTION operate on you? NOT FORmetabolism SALE OR is bas DISTRIBUTIONed on the principles of ______Review Questions 17
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. and ______. If this is true, do you think that Is it likely to survive long enough to pass on its genes praying for good harvests or for rain is effective? for this particular skin pattern? Now imagine that the © Jones 15. & Bartlett The fifth concept Learning, used to LLCunderstand plants is that plants© Jones deer’s& Bartlett environment Learning, changes. LLCAll hunting is outlawed. NOT FOR SALEmust surviveOR DISTRIBUTION in their own ______.NOT FORThere SALE are notOR even DISTRIBUTION any poachers—no hunters at all try Imagine a plant adapted to a desert and one adapted to to kill deer. In this new environment, does this skin pat- a rain forest. Do you think that the leaves of one might tern matter any more? Is the deer still poorly adapted? be different from the leaves of the other? That one might 20. Name the three domains, and describe the types of have enlarged roots that can store water and the other organisms in each. Which are prokaryotes? Which are would not need thes©e? Jones Would it & be Bartlett easier to unders Learning,tand LLC eukaryotes? © Jones & Bartlett Learning, LLC a plant’s anatomy andNOT physio FORlogy, SALE all its biologOR DISTRIBUTIONy, if we 21. What are relictual (plesiomNOTorphic) FOR fea SALEtures? DeriORved DISTRIBUTION also know the type of habitat to which it is adapted? (apomorphic) features? Which organisms seem to have 16. What is the eighth concept used for studying plants? It a larger percentage of relictual features—prokaryotes is difficult to avoid using the phrase “in order to” when or eukaryotes? Algae or flowering plants? Amoebas or referring to plants. Change the following sentences to humans? be© moreJones accurate. & Bartlett The first oneLearning, is done as anLLC example: 22. It is important© Jones to &dist Bartlettinguish betw Learning,een plants andLLC the a. NOTPlants FOR hav SALEe leaves ORin order DISTRIBUTION to photosynthesize. study NOTof plants—that FOR SALE is, the rea ORlity of DISTRIBUTION the plant world and “Plants have leaves that photosynthesize,” or the model of it presented in this book and in lecture. Do “photosynthesis in plants occurs in leaves.” we already know everything there is to be known about b. Plants have flowers in order to reproduce. plants? Have we discovered every plant species that c. Plant cells divide in order to make more cells. exists? Are all of our hypotheses about plants correct? © Jones & Bartlett d. Wind-pollinated Learning, pla LLCnts have their flowers located© Jones23. Plants& Bartlett are part ofLearning, ______. LLC The study of plants NOT FOR SALEhigh OR above DISTRIBUTION the ground in order to be exposed toNOT FORattempts SALE to OR crea DISTRIBUTIONte a ______of that stronger wind. and build a vocabulary to exchange ______e. Some plants have red flowers to attract hummingbirds. about the reality. Can our model ever be incorrect? f. After I eat dinner, my stomach secretes acid in Can reality be incorrect? If our model—our hypothe- order to help digest the food. ses and theories—does not predict accurately, which is 17. Life on Earth began© abo Jonesut ______& Bartlett ______Learning, LLC wrong—reality or the model?© Jones & Bartlett Learning, LLC years ago. At first, orgaNOTnisms FOR were SALE simple , ORlike presDISTRIBUTIONent- 24. As you read, you will NOTdeal wit FORh two SALE types of OR infor DISTRIBUTION- day ______. mation: ______and ______18. When organisms reproduce, some of their offspring are ______. Which of these are reasonably poorly adapted, and they do not grow and reproduce as accurate and trustworthy? The other is more difficult. well as the offspring that are well adapted. This is called Why? If the second type does not make any kind of ______© Jones & Bartlett ______. Learning, LLC prediction© Jones about the& Bartlettoutcome of Learning, a future obser LLCvation 19. LookNOT at FOR Figure SALE 1-12. What OR is DISTRIBUTIONthe fifth concept used for or experiment,NOT FOR wou SALEld there ORbe any DISTRIBUTION way to determine understanding plants (in the section Using Concepts whether it is accurate? to Understand Plants)? We do not know for certain 25. This chapter closes by suggesting that you keep in mind what the environment of this deer is, but would you two questions as you study this book and plants them- guess that the deer is well adapted or poorly adapted? selves. What are the two questions? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION
Design Credits: Hummingbird: © Tongho58/Moment/Getty; Green plant cells: © ShutterStock, Inc./Nataliya Hora; Purple tulip: © ShutterStock, Inc./Marie C Fields; Dandelion: © ShutterStock, Inc./danielkreissl; Poppy: © ShutterStock, Inc./Saruri; Plant icon: © ShutterStock, Inc./Vector; Digging man icon: © ShutterStock, Inc./Z-art
© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 18 Chapter 1: Introduction to Plants and Botany
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.